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  • Error with my Android Application httpGet

    - by Coombes
    Basically I'm getting a strange issue with my Android application, it's supposed to grab a JSON Array and print out some values, the class looks like this: ShowComedianActivity.class package com.example.connecttest; public class ShowComedianActivity extends Activity{ TextView name; TextView add; TextView email; TextView tel; String id; // Progress Dialog private ProgressDialog pDialog; //JSON Parser class JSONParser jsonParser = new JSONParser(); // Single Comedian url private static final String url_comedian_details = "http://86.9.71.17/connect/get_comedian_details.php"; // JSON Node names private static final String TAG_SUCCESS = "success"; private static final String TAG_COMEDIAN = "comedian"; private static final String TAG_ID = "id"; private static final String TAG_NAME = "name"; private static final String TAG_ADDRESS = "address"; private static final String TAG_EMAIL = "email"; private static final String TAG_TEL = "tel"; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.show_comedian); // Getting Comedian Details from intent Intent i = getIntent(); // Getting id from intent id = i.getStringExtra(TAG_ID); new GetComedianDetails().execute(); } class GetComedianDetails extends AsyncTask<String, String, String>{ protected void onPreExecute(){ super.onPreExecute(); pDialog = new ProgressDialog(ShowComedianActivity.this); pDialog.setMessage("Fetching Comedian details. Please wait..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected String doInBackground(String... params) { runOnUiThread(new Runnable(){ public void run(){ int success; try{ //Building parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("id",id)); // Getting comedian details via HTTP request // Uses a GET request JSONObject json = jsonParser.makeHttpRequest(url_comedian_details, "GET", params); // Check Log for json response Log.d("Single Comedian details", json.toString()); //JSON Success tag success = json.getInt(TAG_SUCCESS); if(success == 1){ // Succesfully received product details JSONArray comedianObj = json.getJSONArray(TAG_COMEDIAN); //JSON Array // get first comedian object from JSON Array JSONObject comedian = comedianObj.getJSONObject(0); // comedian with id found name = (TextView) findViewById(R.id.name); add = (TextView) findViewById(R.id.add); email = (TextView) findViewById(R.id.email); tel = (TextView) findViewById(R.id.tel); // Set text to details name.setText(comedian.getString(TAG_NAME)); add.setText(comedian.getString(TAG_ADDRESS)); email.setText(comedian.getString(TAG_EMAIL)); tel.setText(comedian.getString(TAG_TEL)); } } catch (JSONException e){ e.printStackTrace(); } } }); return null; } } } And my JSON Parser class looks like: package com.example.connecttest; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } // function get json from url // by making HTTP POST or GET method public JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } Now when I run a debug it's querying the correct address with ?id=1 on the end of the URL, and when I navigate to that url I get the following JSON Array: {"success":1,"comedian":[{"id":"1","name":"Michael Coombes","address":"5 Trevethenick Road","email":"[email protected]","tel":"xxxxxxxxxxxx"}]} However my app just crashes, the log-cat report looks like this: 03-22 02:05:02.140: E/Trace(3776): error opening trace file: No such file or directory (2) 03-22 02:05:04.590: E/AndroidRuntime(3776): FATAL EXCEPTION: main 03-22 02:05:04.590: E/AndroidRuntime(3776): android.os.NetworkOnMainThreadException 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connect(IoBridge.java:112) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.Socket.connect(Socket.java:842) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.JSONParser.makeHttpRequest(JSONParser.java:62) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.ShowComedianActivity$GetComedianDetails$1.run(ShowComedianActivity.java:89) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.handleCallback(Handler.java:615) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.dispatchMessage(Handler.java:92) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Looper.loop(Looper.java:137) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.app.ActivityThread.main(ActivityThread.java:4745) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invokeNative(Native Method) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invoke(Method.java:511) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-22 02:05:04.590: E/AndroidRuntime(3776): at dalvik.system.NativeStart.main(Native Method) From this I'm guessing the error is in the jsonParser.makeHttpRequest however I can't for the life of me figure out what's going wrong and was hoping someone brighter than I could illuminate me.

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  • Flex 4: Getter getting before setter sets

    - by Steve
    I've created an AS class to use as a data model, shown here: package { import mx.controls.Alert; import mx.rpc.events.FaultEvent; import mx.rpc.events.ResultEvent; import mx.rpc.http.HTTPService; public class Model { private var xmlService:HTTPService; private var _xml:XML; private var xmlChanged:Boolean = false; public function Model() { } public function loadXML(url:String):void { xmlService = new HTTPService(); if (!url) xmlService.url = "DATAPOINTS.xml"; else xmlService.url = url; xmlService.resultFormat = "e4x"; xmlService.addEventListener(ResultEvent.RESULT, setXML); xmlService.addEventListener(FaultEvent.FAULT, faultXML); xmlService.send(); } private function setXML(event:ResultEvent):void { xmlChanged = true; this._xml = event.result as XML; } private function faultXML(event:FaultEvent):void { Alert.show("RAF data could not be loaded."); } public function get xml():XML { return _xml; } } } And in my main application, I'm initiating the app and calling the loadXML function to get the XML: <fx:Script> <![CDATA[ import mx.containers.Form; import mx.containers.FormItem; import mx.containers.VBox; import mx.controls.Alert; import mx.controls.Button; import mx.controls.Label; import mx.controls.Text; import mx.controls.TextInput; import spark.components.NavigatorContent; private function init():void { var model:Model = new Model(); model.loadXML(null); var xml:XML = model.xml; } ]]> </fx:Script> The trouble I'm having is that the getter function is running before loadXML has finished, so the XML varible in my main app comes up undefined in stack traces. How do I put a condition in here somewhere that tells the getter to wait until the loadXML() function has finished before running?

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  • Java Box Class: Unsolvable: aligning components to the left or right

    - by user323186
    I have been trying to left align buttons contained in a Box to the left, with no success. They align left alright, but for some reason dont shift all the way left as one would imagine. I attach the code below. Please try compiling it and see for yourself. Seems bizarre to me. Thanks, Eric import java.awt.Dimension; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JScrollPane; import javax.swing.JTextArea; public class MainGUI extends Box implements ActionListener{ //Create GUI Components Box centerGUI=new Box(BoxLayout.X_AXIS); Box bottomGUI=new Box(BoxLayout.X_AXIS); //centerGUI subcomponents JTextArea left=new JTextArea(), right=new JTextArea(); JScrollPane leftScrollPane = new JScrollPane(left), rightScrollPane = new JScrollPane(right); //bottomGUI subcomponents JButton encrypt=new JButton("Encrypt"), decrypt=new JButton("Decrypt"), close=new JButton("Close"), info=new JButton("Info"); //Create Menubar components JMenuBar menubar=new JMenuBar(); JMenu fileMenu=new JMenu("File"); JMenuItem open=new JMenuItem("Open"), save=new JMenuItem("Save"), exit=new JMenuItem("Exit"); int returnVal =0; public MainGUI(){ super(BoxLayout.Y_AXIS); initCenterGUI(); initBottomGUI(); initFileMenu(); add(centerGUI); add(bottomGUI); addActionListeners(); } private void addActionListeners() { open.addActionListener(this); save.addActionListener(this); exit.addActionListener(this); encrypt.addActionListener(this); decrypt.addActionListener(this); close.addActionListener(this); info.addActionListener(this); } private void initFileMenu() { fileMenu.add(open); fileMenu.add(save); fileMenu.add(exit); menubar.add(fileMenu); } public void initCenterGUI(){ centerGUI.add(leftScrollPane); centerGUI.add(rightScrollPane); } public void initBottomGUI(){ bottomGUI.setAlignmentX(LEFT_ALIGNMENT); //setBorder(BorderFactory.createLineBorder(Color.BLACK)); bottomGUI.add(encrypt); bottomGUI.add(decrypt); bottomGUI.add(close); bottomGUI.add(info); } @Override public void actionPerformed(ActionEvent arg0) { // find source of the action Object source=arg0.getSource(); //if action is of such a type do the corresponding action if(source==close){ kill(); } else if(source==open){ //CHOOSE FILE File file1 =chooseFile(); String input1=readToString(file1); System.out.println(input1); left.setText(input1); } else if(source==decrypt){ //decrypt everything in Right Panel and output in left panel decrypt(); } else if(source==encrypt){ //encrypt everything in left panel and output in right panel encrypt(); } else if(source==info){ //show contents of info file in right panel doInfo(); } else { System.out.println("Error"); //throw new UnimplementedActionException(); } } private void doInfo() { // TODO Auto-generated method stub } private void encrypt() { // TODO Auto-generated method stub } private void decrypt() { // TODO Auto-generated method stub } private String readToString(File file) { FileReader fr = null; try { fr = new FileReader(file); } catch (FileNotFoundException e1) { e1.printStackTrace(); } BufferedReader br=new BufferedReader(fr); String line = null; try { line = br.readLine(); } catch (IOException e) { e.printStackTrace(); } String input=""; while(line!=null){ input=input+"\n"+line; try { line=br.readLine(); } catch (IOException e) { e.printStackTrace(); } } return input; } private File chooseFile() { //Create a file chooser final JFileChooser fc = new JFileChooser(); returnVal = fc.showOpenDialog(fc); return fc.getSelectedFile(); } private void kill() { System.exit(0); } public static void main(String[] args) { // TODO Auto-generated method stub MainGUI test=new MainGUI(); JFrame f=new JFrame("Tester"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setJMenuBar(test.menubar); f.setPreferredSize(new Dimension(600,400)); //f.setUndecorated(true); f.add(test); f.pack(); f.setVisible(true); } }

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  • Singleton constructor question

    - by gillyb
    Hi, I created a Singleton class in c#, with a public property that I want to initialize when the Singleton is first called. This is the code I wrote : public class BL { private ISessionFactory _sessionFactory; public ISessionFactory SessionFactory { get { return _sessionFactory; } set { _sessionFactory = value; } } private BL() { SessionFactory = Dal.SessionFactory.CreateSessionFactory(); } private object thisLock = new object(); private BL _instance = null; public BL Instance { get { lock (thisLock) { if (_instance == null) { _instance = new BL(); } return _instance; } } } } As far as I know, when I address the Instance BL object in the BL class for the first time, it should load the constructor and that should initialize the SessionFactory object. But when I try : BL.Instance.SessionFactory.OpenSession(); I get a Null Reference Exception, and I see that SessionFactory is null... why?

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  • how to update an Android ListActivity on changing data of the connected SimpleCursorAdapter

    - by 4485670
    I have the following code. What I want to achieve is to update the shown list when I click an entry so I can traverse through the list. I found the two uncommented ways to do it here on stackoverflow, but neither works. I also got the advice to create a new ListActivity on the data update, but that sounds like wasting resources? EDIT: I found the solution myself. All you need to do is call "SimpleCursorAdapter.changeCursor(new Cursor);". No notifying, no things in UI-Thread or whatever. import android.app.ListActivity; import android.database.Cursor; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.ListView; import android.widget.SimpleCursorAdapter; public class MyActivity extends ListActivity { private DepartmentDbAdapter mDbHelper; private Cursor cursor; private String[] from = new String[] { DepartmentDbAdapter.KEY_NAME }; private int[] to = new int[] { R.id.text1 }; private SimpleCursorAdapter notes; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.departments_list); mDbHelper = new DepartmentDbAdapter(this); mDbHelper.open(); // Get all of the departments from the database and create the item list cursor = mDbHelper.fetchSubItemByParentId(1); this.startManagingCursor(cursor); // Now create an array adapter and set it to display using our row notes = new SimpleCursorAdapter(this, R.layout.department_row, cursor, from, to); this.setListAdapter(notes); } @Override protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); // get new data and update the list this.updateData(safeLongToInt(id)); } /** * update data for the list * * @param int departmentId id of the parent department */ private void updateData(int departmentId) { // close the old one, get a new one cursor.close(); cursor = mDbHelper.fetchSubItemByParentId(departmentId); // change the cursor of the adapter to the new one notes.changeCursor(cursor); } /** * safely convert long to in to save memory * * @param long l the long variable * * @return integer */ public static int safeLongToInt(long l) { if (l < Integer.MIN_VALUE || l > Integer.MAX_VALUE) { throw new IllegalArgumentException (l + " cannot be cast to int without changing its value."); } return (int) l; } }

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  • Searching in an Arraylist

    - by Puchatek
    Currently I have two classes. A Classroom class and a School class. I would like to write a method in the School class public void showClassRoomDetails which would find the classroom details by only using the teacherName. e.g. teacherName = Daniel className = Science teacherName = Bob className = Maths so when I input Bob, it would print out Bob and Maths many, thanks public class Classroom { private String classRoomName; private String teacherName; public void setClassRoomName(String newClassRoomName) { classRoomName = newClassRoomName; } public String returnClassRoomName() { return classRoomName; } public void setTeacherName(String newTeacherName) { teacherName = newTeacherName; } public String returnTeacherName() { return teacherName; } } import java.util.ArrayList; public class School { private ArrayList<Classroom> classrooms; private String classRoomName; private String teacherName; public School() { classrooms = new ArrayList<Classroom>(); } public void addClassRoom(Classroom newClassRoom, String theClassRoomName) { classrooms.add(newClassRoom); classRoomName = theClassRoomName; } public void addTeacherToClassRoom(int classroomId, String TeacherName) { if (classroomId < classrooms.size() ) { classrooms.get(classroomId).setTeacherName(TeacherName); } } public void showClassRoomDetails { //loop System.out.println(returnClassRoomName); System.out.println(returnTeacherName); } }

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  • Hotmail financé par la publicité ciblée ? L'idée ferait son chemin, mais sur un modèle différent de

    Hotmail financé par la publicité ciblée ? L'idée ferait son chemin mais sur un modèle différent de celui de G-mail Tim O'Brien, un cadre de Microsoft, vient de participer à une conférence sur les sujets du Cloud et des SaaS (Software as a service), la bien nommée SaaSCon 2010 de Santa Clara, en Californie. A cette occasion, O'Brien a tenu à rappeler que garder et protéger les données de tous les utilisateurs de Hotmail, une des messageries les plus populaires au monde, sur les serveurs de Microsoft était un défi quotidien et sans cesse renouvelé. Il note par ailleurs que le degré de confiance entre les utilisateurs de services hébergés de type Cloud (et donc de Hotmail) et ...

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  • Two entities with @ManyToOne should join the same table

    - by Ivan Yatskevich
    I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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  • How to access a field's value in an object using reflection

    - by kentcdodds
    My Question: How to overcome an IllegalAccessException to access the value of a an object's field using reflection. Expansion: I'm trying to learn about reflection to make some of my projects more generic. I'm running into an IllegalAccessException when trying to call field.getValue(object) to get the value of that field in that object. I can get the name and type just fine. If I change the declaration from private to public then this works fine. But in an effort to follow the "rules" of encapsulation I don't want to do this. Any help would be greatly appreciated! Thanks! My Code: package main; import java.lang.reflect.Field; public class Tester { public static void main(String args[]) throws Exception { new Tester().reflectionTest(); } public void reflectionTest() throws Exception { Person person = new Person("John Doe", "555-123-4567", "Rover"); Field[] fields = person.getClass().getDeclaredFields(); for (Field field : fields) { System.out.println("Field Name: " + field.getName()); System.out.println("Field Type: " + field.getType()); System.out.println("Field Value: " + field.get(person)); //The line above throws: Exception in thread "main" java.lang.IllegalAccessException: Class main.Tester can not access a member of class main.Tester$Person with modifiers "private final" } } public class Person { private final String name; private final String phoneNumber; private final String dogsName; public Person(String name, String phoneNumber, String dogsName) { this.name = name; this.phoneNumber = phoneNumber; this.dogsName = dogsName; } } } The Output: run: Field Name: name Field Type: class java.lang.String Exception in thread "main" java.lang.IllegalAccessException: Class main.Tester can not access a member of class main.Tester$Person with modifiers "private final" at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:95) at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:261) at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:253) at java.lang.reflect.Field.doSecurityCheck(Field.java:983) at java.lang.reflect.Field.getFieldAccessor(Field.java:927) at java.lang.reflect.Field.get(Field.java:372) at main.Tester.reflectionTest(Tester.java:17) at main.Tester.main(Tester.java:8) Java Result: 1 BUILD SUCCESSFUL (total time: 0 seconds)

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  • Null-free "maps": Is a callback solution slower than tryGet()?

    - by David Moles
    In comments to "How to implement List, Set, and Map in null free design?", Steven Sudit and I got into a discussion about using a callback, with handlers for "found" and "not found" situations, vs. a tryGet() method, taking an out parameter and returning a boolean indicating whether the out parameter had been populated. Steven maintained that the callback approach was more complex and almost certain to be slower; I maintained that the complexity was no greater and the performance at worst the same. But code speaks louder than words, so I thought I'd implement both and see what I got. The original question was fairly theoretical with regard to language ("And for argument sake, let's say this language don't even have null") -- I've used Java here because that's what I've got handy. Java doesn't have out parameters, but it doesn't have first-class functions either, so style-wise, it should suck equally for both approaches. (Digression: As far as complexity goes: I like the callback design because it inherently forces the user of the API to handle both cases, whereas the tryGet() design requires callers to perform their own boilerplate conditional check, which they could forget or get wrong. But having now implemented both, I can see why the tryGet() design looks simpler, at least in the short term.) First, the callback example: class CallbackMap<K, V> { private final Map<K, V> backingMap; public CallbackMap(Map<K, V> backingMap) { this.backingMap = backingMap; } void lookup(K key, Callback<K, V> handler) { V val = backingMap.get(key); if (val == null) { handler.handleMissing(key); } else { handler.handleFound(key, val); } } } interface Callback<K, V> { void handleFound(K key, V value); void handleMissing(K key); } class CallbackExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; private Callback<String, String> handler; public CallbackExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); handler = new Callback<String, String>() { public void handleFound(String key, String value) { found.add(key + ": " + value); } public void handleMissing(String key) { missing.add(key); } }; } void test() { CallbackMap<String, String> cbMap = new CallbackMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; cbMap.lookup(key, handler); } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } Now, the tryGet() example -- as best I understand the pattern (and I might well be wrong): class TryGetMap<K, V> { private final Map<K, V> backingMap; public TryGetMap(Map<K, V> backingMap) { this.backingMap = backingMap; } boolean tryGet(K key, OutParameter<V> valueParam) { V val = backingMap.get(key); if (val == null) { return false; } valueParam.value = val; return true; } } class OutParameter<V> { V value; } class TryGetExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; public TryGetExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); } void test() { TryGetMap<String, String> tgMap = new TryGetMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; OutParameter<String> out = new OutParameter<String>(); if (tgMap.tryGet(key, out)) { found.add(key + ": " + out.value); } else { missing.add(key); } } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } And finally, the performance test code: public static void main(String[] args) { int size = 200000; Map<String, String> map = new HashMap<String, String>(); for (int i = 0; i < size; i++) { String val = (i % 5 == 0) ? null : "value" + i; map.put("key" + i, val); } long totalCallback = 0; long totalTryGet = 0; int iterations = 20; for (int i = 0; i < iterations; i++) { { TryGetExample tryGet = new TryGetExample(map); long tryGetStart = System.currentTimeMillis(); tryGet.test(); totalTryGet += (System.currentTimeMillis() - tryGetStart); } System.gc(); { CallbackExample callback = new CallbackExample(map); long callbackStart = System.currentTimeMillis(); callback.test(); totalCallback += (System.currentTimeMillis() - callbackStart); } System.gc(); } System.out.println("Avg. callback: " + (totalCallback / iterations)); System.out.println("Avg. tryGet(): " + (totalTryGet / iterations)); } On my first attempt, I got 50% worse performance for callback than for tryGet(), which really surprised me. But, on a hunch, I added some garbage collection, and the performance penalty vanished. This fits with my instinct, which is that we're basically talking about taking the same number of method calls, conditional checks, etc. and rearranging them. But then, I wrote the code, so I might well have written a suboptimal or subconsicously penalized tryGet() implementation. Thoughts?

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  • What is the proper way to use a Logger in a Serializable Java class?

    - by Tim Visher
    I have the following (doctored) class in a system I'm working on and Findbugs is generating a SE_BAD_FIELD warning and I'm trying to understand why it would say that before I fix it in the way that I thought I would. The reason I'm confused is because the description would seem to indicate that I had used no other non-serializable instance fields in the class but bar.model.Foo is also not serializable and used in the exact same way (as far as I can tell) but Findbugs generates no warning for it. import bar.model.Foo; import java.io.File; import java.io.Serializable; import java.util.List; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class Demo implements Serializable { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final File file; private final List<Foo> originalFoos; private Integer count; private int primitive = 0; public Demo() { for (Foo foo : originalFoos) { this.logger.debug(...); } } ... } My initial blush at a solution is to get a logger reference from the factory right as I use it: public DispositionFile() { Logger logger = LoggerFactory.getLogger(this.getClass()); for (Foo foo : originalFoos) { this.logger.debug(...); } } That doesn't seem particularly efficient, though. Thoughts?

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  • Help with method logic in Java, hw

    - by Crystal
    I have a Loan class that in its printPayment method, it prints the amortization table of a loan for a hw assignment. We are also to implement a print first payment method, and a print last payment method. Since my calculation is done in the printPayment method, I didn't know how I could get the value in the first or last iteration of the loop and print that amount out. One way I can think of is to write a new method that might return that value, but I wasn't sure if there was a better way. Here is my code: public abstract class Loan { public void setClient(Person client) { this.client = client; } public Person getClient() { return client; } public void setLoanId() { loanId = nextId; nextId++; } public int getLoanId() { return loanId; } public void setInterestRate(double interestRate) { this.interestRate = interestRate; } public double getInterestRate() { return interestRate; } public void setLoanLength(int loanLength) { this.loanLength = loanLength; } public int getLoanLength() { return loanLength; } public void setLoanAmount(double loanAmount) { this.loanAmount = loanAmount; } public double getLoanAmount() { return loanAmount; } public void printPayments() { double monthlyInterest; double monthlyPrincipalPaid; double newPrincipal; int paymentNumber = 1; double monthlyInterestRate = interestRate / 1200; double monthlyPayment = loanAmount * (monthlyInterestRate) / (1 - Math.pow((1 + monthlyInterestRate),( -1 * loanLength))); System.out.println("Payment Number | Interest | Principal | Loan Balance"); // amortization table while (loanAmount >= 0) { monthlyInterest = loanAmount * monthlyInterestRate; monthlyPrincipalPaid = monthlyPayment - monthlyInterest; newPrincipal = loanAmount - monthlyPrincipalPaid; loanAmount = newPrincipal; System.out.printf("%d, %.2f, %.2f, %.2f", paymentNumber++, monthlyInterest, monthlyPrincipalPaid, loanAmount); } } /* //method to print first payment public double getFirstPayment() { } method to print last payment public double getLastPayment() { }*/ private Person client; private int loanId; private double interestRate; private int loanLength; private double loanAmount; private static int nextId = 1; } Thanks!

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  • C# struct with object as data member

    - by source-energy
    As we know, in C# structs are passed by value, not by reference. So if I have a struct with the following data members: private struct MessageBox { // data members private DateTime dm_DateTimeStamp; // a struct type private TimeSpan dm_TimeSpanInterval; // also a struct private ulong dm_MessageID; // System.Int64 type, struct private String dm_strMessage; // an object (hence a reference is stored here) // more methods, properties, etc ... } So when a MessageBox is passed as a parameter, a COPY is made on the stack, right? What does that mean in terms of how the data members are copied? The first two are struct types, so copies should be made of DateTime and TimeSpan. The third type is a primitive, so it's also copied. But what about the dm_strMessage, which is a reference to an object? When it's copied, another reference to the same String is created, right? The object itself resides in the heap, and is NOT copied (there is only one instance of it on the heap.) So now we have to references to the same object of type String. If the two references are accessed from different threads, it's conceivable that the String object could be corrupted by being modified from two different directions simultaneously. The MSDN documentation says that System.String is thread safe. Does that mean that the String class has a built-in mechanism to prevent an object being corrupted in exactly the type of situation described here? I'm trying to figure out if my MessageBox struct has any potential flaws / pitfalls being a structure vs. a class. Thanks for any input. Source.Energy.

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  • vlcj not displaying the video

    - by Cássio Eudardo
    I'm using vlcj to play video, but the video doesn't display on some computers(i tested in 4 and worked on 2, all windows), on 1 it displays the button but not the video and on the other it just display a gray background without the button. I tested .wmv and .avi files. I'm using the following code: public class Video extends JFrame implements WindowListener{ private JPanel contentPane; private JButton btnClose; private Dimension size; private float aspectRatio; private EmbeddedMediaPlayer mediaPlayer; public Video() { try { size = Toolkit.getDefaultToolkit().getScreenSize(); aspectRatio = (float)size.width/size.height; String file = "..."; btnClose = new JButton("X"); btnClose.addActionListener(new ActionListener() {...}); btnClose.setBounds(640 - 50, 10, 40, 40); setBounds(size.width/2 - 320, (int)(size.height - 40*aspectRatio) - 250, 640, 200); contentPane = new JPanel(); contentPane.setLayout(null); setContentPane(contentPane); WindowsCanvas surface = new WindowsCanvas(); contentPane.setBounds(0, 0, 640, 200); surface.setBounds(0, 0, 640, 200); MediaPlayerFactory factory = new MediaPlayerFactory(new String("--no-video-title-show")); mediaPlayer = factory.newEmbeddedMediaPlayer(); surface.addMouseListener(new MouseListener() {...}); contentPane.add(btnClose); contentPane.add(surface); setVisible(true); mediaPlayer.setVideoSurface(factory.newVideoSurface(surface)); mediaPlayer.setRepeat(true); mediaPlayer.playMedia(file); } catch(Exception e) { } }}

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  • Doubt about instance creation by using Spring framework ???

    - by Arthur Ronald F D Garcia
    Here goes a command object which needs to be populated from a Spring form public class Person { private String name; private Integer age; /** * on-demand initialized */ private Address address; // getter's and setter's } And Address public class Address { private String street; // getter's and setter's } Now suppose the following MultiActionController @Component public class PersonController extends MultiActionController { @Autowired @Qualifier("personRepository") private Repository<Person, Integer> personRepository; /** * mapped To /person/add */ public ModelAndView add(HttpServletRequest request, HttpServletResponse response, Person person) throws Exception { personRepository.add(person); return new ModelAndView("redirect:/home.htm"); } } Because Address attribute of Person needs to be initialized on-demand, i need to override newCommandObject to create an instance of Person to initiaze address property. Otherwise, i will get NullPointerException @Component public class PersonController extends MultiActionController { /** * code as shown above */ @Override public Object newCommandObject(Class clazz) thorws Exception { if(clazz.isAssignableFrom(Person.class)) { Person person = new Person(); person.setAddress(new Address()); return person; } } } Ok, Expert Spring MVC and Web Flow says Options for alternate object creation include pulling an instance from a BeanFactory or using method injection to transparently return a new instance. First option pulling an instance from a BeanFactory can be written as @Override public Object newCommandObject(Class clazz) thorws Exception { /** * Will retrieve a prototype instance from ApplicationContext whose name matchs its clazz.getSimpleName() */ getApplicationContext().getBean(clazz.getSimpleName()); } But what does he want to say by using method injection to transparently return a new instance ??? Can you show how i implement what he said ??? ATT: I know this funcionality can be filled by a SimpleFormController instead of MultiActionController. But it is shown just as an example, nothing else

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  • Repaint() not calling paint() in Java

    - by Joshua Auriemma
    Let me start off by saying I know I've violated some basic Java principles in this messy code, but I'm desperately trying to finish a program by Tuesday for a social science experiment, and I don't know Java, so I'm basically just fumbling through it for now. With that disclaimer out of the way, I have a separate program working where a circle is moving around the screen and the user must click on it. It works fine when its in its own separate class file, but when I add the code to my main program, it's no longer working. I don't even really understand why repaint() calls my paint() function — as far as I'm concerned, it's magic, but I've noticed that repaint() calls paint() in my test program, but not in the more complicated actual program, and I assume that's why the circle is no longer painting on my program. Entire code is below: import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import javax.swing.*; import java.awt.event.*; import java.awt.geom.Ellipse2D; import java.io.FileReader; import java.io.IOException; import java.util.Calendar; public class Reflexology1 extends JFrame{ private static final long serialVersionUID = -1295261024563143679L; private Ellipse2D ball = new Ellipse2D.Double(0, 0, 25, 25); private Timer moveBallTimer; int _ballXpos, _ballYpos; JButton button1, button2; JButton movingButton; JTextArea textArea1; int buttonAClicked, buttonDClicked; private long _openTime = 0; private long _closeTime = 0; JPanel thePanel = new JPanel(); JPanel thePlacebo = new JPanel(); final JFrame frame = new JFrame("Reflexology"); final JFrame frame2 = new JFrame("The Test"); JLabel label1 = new JLabel("Press X and then click the moving dot as fast as you can."); public static void main(String[] args){ new Reflexology1(); } public Reflexology1(){ frame.setSize(600, 475); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setTitle("Reflexology 1.0"); frame.setResizable(false); frame2.setSize(600, 475); frame2.setLocationRelativeTo(null); frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame2.setTitle("Reflexology 1.0"); frame2.setResizable(false); button1 = new JButton("Accept"); button2 = new JButton("Decline"); //movingButton = new JButton("Click Me"); ListenForAcceptButton lForAButton = new ListenForAcceptButton(); ListenForDeclineButton lForDButton = new ListenForDeclineButton(); button1.addActionListener(lForAButton); button2.addActionListener(lForDButton); //movingButton.addActionListener(lForMButton); JTextArea textArea1 = new JTextArea(24, 50); textArea1.setText("Tracking Events\n"); textArea1.setLineWrap(true); textArea1.setWrapStyleWord(true); textArea1.setSize(15, 50); textArea1.setEditable(false); FileReader reader = null; try { reader = new FileReader("EULA.txt"); textArea1.read(reader, "EULA.txt"); } catch (IOException exception) { System.err.println("Problem loading file"); exception.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException exception) { System.err.println("Error closing reader"); exception.printStackTrace(); } } } JScrollPane scrollBar1 = new JScrollPane(textArea1, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); AdjustmentListener listener = new MyAdjustmentListener(); thePanel.add(scrollBar1); thePanel.add(button1); thePanel.add(button2); frame.add(thePanel); ListenForMouse lForMouse = new ListenForMouse(); thePlacebo.addMouseListener(lForMouse); thePlacebo.add(label1); frame2.add(thePlacebo); ListenForWindow lForWindow = new ListenForWindow(); frame.addWindowListener(lForWindow); frame2.addKeyListener(new KeyAdapter() { public void keyPressed(KeyEvent e){ if(e.getKeyChar() == 'X' || e.getKeyChar() == 'x') {moveBallTimer.start();} } }); frame.setVisible(true); moveBallTimer = new Timer(1000, new ActionListener() { public void actionPerformed(ActionEvent e) { moveBall(); System.out.println("Timer started!"); repaint(); } }); addKeyListener(new KeyAdapter() { public void keyPressed(KeyEvent e) { if(frame2.isVisible()){ moveBallTimer.start(); } } }); } private class ListenForAcceptButton implements ActionListener{ public void actionPerformed(ActionEvent e){ if (e.getSource() == button1){ Calendar ClCDateTime = Calendar.getInstance(); System.out.println(ClCDateTime.getTimeInMillis() - _openTime); _closeTime = ClCDateTime.getTimeInMillis() - _openTime; //frame.getContentPane().remove(thePanel); //thePlacebo.addKeyListener(lForKeys); //frame.getContentPane().add(thePlacebo); //frame.repaint(); //moveBallTimer.start(); frame.setVisible(false); frame2.setVisible(true); frame2.revalidate(); frame2.repaint(); } } } private class ListenForDeclineButton implements ActionListener{ public void actionPerformed(ActionEvent e){ if (e.getSource() == button2){ JOptionPane.showMessageDialog(Reflexology1.this, "You've declined the license agreement. DO NOT RESTART the program. Please go inform a researcher that you have declined the agreement.", "WARNING", JOptionPane.INFORMATION_MESSAGE); System.exit(0); } } } private class ListenForWindow implements WindowListener{ public void windowActivated(WindowEvent e) { //textArea1.append("Window is active"); } // if this.dispose() is called, this is called: public void windowClosed(WindowEvent arg0) { } // When a window is closed from a menu, this is called: public void windowClosing(WindowEvent arg0) { } // Called when the window is no longer the active window: public void windowDeactivated(WindowEvent arg0) { //textArea1.append("Window is NOT active"); } // Window gone from minimized to normal state public void windowDeiconified(WindowEvent arg0) { //textArea1.append("Window is in normal state"); } // Window has been minimized public void windowIconified(WindowEvent arg0) { //textArea1.append("Window is minimized"); } // Called when the Window is originally created public void windowOpened(WindowEvent arg0) { //textArea1.append("Let there be Window!"); Calendar OlCDateTime = Calendar.getInstance(); _openTime = OlCDateTime.getTimeInMillis(); //System.out.println(_openTime); } } private class MyAdjustmentListener implements AdjustmentListener { public void adjustmentValueChanged(AdjustmentEvent arg0) { AdjustmentEvent scrollBar1; //System.out.println(scrollBar1.getValue())); } } public void paint(Graphics g) { //super.paint(g); frame2.paint(g); Graphics2D g2d = (Graphics2D) g; g2d.setColor(Color.RED); g2d.fill(ball); System.out.println("Calling fill()"); } protected void moveBall() { //System.out.println("I'm in the moveBall() function!"); int width = getWidth(); int height = getHeight(); int min, max, randomX, randomY; min =200; max = -200; randomX = min + (int)(Math.random() * ((max - min)+1)); randomY = min + (int)(Math.random() * ((max - min)+1)); //System.out.println(randomX + ", " + randomY); Rectangle ballBounds = ball.getBounds(); //System.out.println(ballBounds.x + ", " + ballBounds.y); if (ballBounds.x + randomX < 0) { randomX = 200; } else if (ballBounds.x + ballBounds.width + randomX > width) { randomX = -200; } if (ballBounds.y + randomY < 0) { randomY = 200; } else if (ballBounds.y + ballBounds.height + randomY > height) { randomY = -200; } ballBounds.x += randomX; ballBounds.y += randomY; _ballXpos = ballBounds.x; _ballYpos = ballBounds.y; ball.setFrame(ballBounds); } public void start() { moveBallTimer.start(); } public void stop() { moveBallTimer.stop(); } private class ListenForMouse implements MouseListener{ // Called when the mouse is clicked public void mouseClicked(MouseEvent e) { //System.out.println("Mouse Panel pos: " + e.getX() + " " + e.getY() + "\n"); if (e.getX() >=_ballXpos && e.getX() <= _ballXpos + 25 && e.getY() <=_ballYpos && e.getY() >= _ballYpos - 25 ) { System.out.println("TRUE"); } System.out.println("{e.getX(): " + e.getX() + " / " + "_ballXpos: " + _ballXpos + " | " + "{e.getY(): " + e.getY() + " / " + "_ballYpos: " + _ballYpos); } public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } } // System.out.println("e.getX(): " + e.getX() + " / " + "_ballXpos: " + _ballXpos); // Mouse over public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } // Mouse left the mouseover area: public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } } Could anyone tell me what I need to do to get repaint() to call the paint() method in the above program? I'm assuming the multiple frames is causing the problem, but that's just a guess. Thanks.

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  • null reference expction in the code

    - by LifeH2O
    I am getting NullReferenceException error on "_attr.Append(xmlNode.Attributes["name"]);". namespace SMAS { class Profiles { private XmlTextReader _profReader; private XmlDocument _profDoc; private const string Url = "http://localhost/teamprofiles.xml"; private const string XPath = "/teams/team-profile"; public XmlNodeList Teams{ get; private set; } private XmlAttributeCollection _attr; public ArrayList Team { get; private set; } public void GetTeams() { _profReader = new XmlTextReader(Url); _profDoc = new XmlDocument(); _profDoc.Load(_profReader); Teams = _profDoc.SelectNodes(XPath); foreach (XmlNode xmlNode in Teams) { _attr.Append(xmlNode.Attributes["name"]); } } } } the teamprofiles.xml file looks like <teams> <team-profile name="Australia"> <stats type="Test"> <span>1877-2010</span> <matches>721</matches> <won>339</won> <lost>186</lost> <tied>2</tied> <draw>194</draw> <percentage>47.01</percentage> </stats> <stats type="Twenty20"> <span>2005-2010</span> <matches>32</matches> <won>18</won> <lost>12</lost> <tied>1</tied> <draw>1</draw> <percentage>59.67</percentage> </stats> </team-profile> <team-profile name="Bangladesh"> <stats type="Test"> <span>2000-2010</span> <matches>66</matches> <won>3</won> <lost>57</lost> <tied>0</tied> <draw>6</draw> <percentage>4.54</percentage> </stats> </team-profile> </teams> I am trying to extract names of all teams in an ArrayList. Then i'll extract all stats of all teams and display them in my application. Can you please help me about that null reference exception?

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  • Preselection in the save dialog (c#)

    - by FullmetalBoy
    Goal: Save a notepad file in the computer. (C#) Problem: I don't know how to make a preselection as "TXT Files(*.txt)" in the "Save as type:" when save dialog display? // Fullmetalboy using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO; namespace Labb2_application { public partial class MainForm : Form { public MainForm() { InitializeComponent(); } private void mnuFileOpen_Click(object sender, EventArgs e) { OpenFileDialog fDialog = new OpenFileDialog(); fDialog.Title = "Öppna"; fDialog.Filter = "Text files|*.txt"; fDialog.InitialDirectory = @"C:\Windows"; fDialog.ShowHelp = true; DialogResult result = fDialog.ShowDialog(); // Show the dialog and get result. if (result == DialogResult.OK) { string fileAdress = fDialog.FileName; try { string textContent = File.ReadAllText(fileAdress); rtxtDisplay.Text = textContent; } catch (IOException) { } } // If syntax } private void mnuFileSave_Click(object sender, EventArgs e) { saveAsFileDialog.ShowDialog(); } private void mnuFileSaveAs_Click(object sender, EventArgs e) { saveAsFileDialog.Filter = "Text files|*.txt"; saveAsFileDialog.ShowDialog(); } private void mnuFileExit_Click(object sender, EventArgs e) { Application.Exit(); } private void saveAsFileDialog_FileOk(object sender, CancelEventArgs e) { string fileNameAddress = saveAsFileDialog.FileName; File.WriteAllText(fileNameAddress, rtxtDisplay.Text); } } // Partial Class }

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