How to call a new thread from button click
- by Lynnooi
Hi,
I'm trying to call a thread on a button click (btn_more) but i cant get it right. The thread is to get some data and update the images. The problem i have is if i only update 4 or 5 images then it works fine. But if i load more than 5 images i will get a force close. At times when the internet is slow I will face the same problem too. Can please help me to solve this problem or provide me some guidance? Here is the error i got from LogCat:
04-19 18:51:44.907: ERROR/AndroidRuntime(1034): Uncaught
handler: thread main exiting due to
uncaught exception 04-19 18:51:44.927:
ERROR/AndroidRuntime(1034):
java.lang.NullPointerException 04-19
18:51:44.927:
ERROR/AndroidRuntime(1034): at
mobile9.android.gallery.GalleryWallpapers.setWallpaperThumb(GalleryWallpapers.java:383)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
mobile9.android.gallery.GalleryWallpapers.access$4(GalleryWallpapers.java:320)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
mobile9.android.gallery.GalleryWallpapers$1.handleMessage(GalleryWallpapers.java:266)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
android.os.Handler.dispatchMessage(Handler.java:99)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
android.os.Looper.loop(Looper.java:123)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
android.app.ActivityThread.main(ActivityThread.java:4310)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
java.lang.reflect.Method.invokeNative(Native
Method) 04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
java.lang.reflect.Method.invoke(Method.java:521)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
04-19 18:51:44.927:
ERROR/AndroidRuntime(1034): at
dalvik.system.NativeStart.main(Native
Method)
My Code:
public class GalleryWallpapers extends Activity implements Runnable {
public static String MODEL = android.os.Build.MODEL ;
private static final String rootURL = "http://www.uploadhub.com/mobile9/gallery/c/";
private int wallpapers_count = 0;
private int ringtones_count = 0;
private int index = 0;
private int folder_id;
private int page;
private int page_counter = 1;
private String family;
private String keyword;
private String xmlURL = "";
private String thread_op = "xml";
private ImageButton btn_back;
private ImageButton btn_home;
private ImageButton btn_filter;
private ImageButton btn_search;
private TextView btn_more;
private ProgressDialog pd;
GalleryExampleHandler myExampleHandler = new GalleryExampleHandler();
Context context = GalleryWallpapers.this.getBaseContext();
Drawable image;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MODEL = "HTC Legend"; // **needs to be remove after testing**
try {
MODEL = URLEncoder.encode(MODEL,"UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.gallerywallpapers);
Bundle b = this.getIntent().getExtras();
family = b.getString("fm").trim();
folder_id = Integer.parseInt(b.getString("fi"));
keyword = b.getString("kw").trim();
page = Integer.parseInt(b.getString("page").trim());
WindowManager w = getWindowManager();
Display d = w.getDefaultDisplay();
final int width = d.getWidth();
final int height = d.getHeight();
xmlURL = rootURL + "wallpapers/1/?output=rss&afm=wallpapers&mdl=" + MODEL + "&awd=" + width + "&aht=" + height;
if (folder_id > 0) {
xmlURL = xmlURL + "&fi=" + folder_id;
}
pd = ProgressDialog.show(GalleryWallpapers.this, "",
"Loading...", true, false);
Thread thread = new Thread(GalleryWallpapers.this);
thread.start();
btn_more = (TextView) findViewById(R.id.btn_more);
btn_more.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
myExampleHandler.filenames.clear();
myExampleHandler.authors.clear();
myExampleHandler.duration.clear();
myExampleHandler.fileid.clear();
btn_more.setBackgroundResource(R.drawable.btn_more_click);
page = page + 1;
thread_op = "xml";
xmlURL = rootURL + "wallpapers/1/?output=rss&afm=wallpapers&mdl=" + MODEL + "&awd=" + width + "&aht=" + height;
xmlURL = xmlURL + "&pg2=" + page;
index = 0;
pd = ProgressDialog.show(GalleryWallpapers.this, "",
"Loading...", true, false);
Thread thread = new Thread(GalleryWallpapers.this);
thread.start();
}
});
}
public void run() {
if(thread_op.equalsIgnoreCase("xml")){
readXML();
}
else if(thread_op.equalsIgnoreCase("getImg")){
getWallpaperThumb();
}
handler.sendEmptyMessage(0);
}
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
int count = 0;
if (!myExampleHandler.filenames.isEmpty()){
count = myExampleHandler.filenames.size();
}
count = 6;
if(thread_op.equalsIgnoreCase("xml")){
pd.dismiss();
thread_op = "getImg";
btn_more.setBackgroundResource(R.drawable.btn_more);
}
else if(thread_op.equalsIgnoreCase("getImg")){
setWallpaperThumb();
index++;
if (index < count){
Thread thread = new Thread(GalleryWallpapers.this);
thread.start();
}
}
}
};
private void readXML(){
if (xmlURL.length() != 0) {
try {
/* Create a URL we want to load some xml-data from. */
URL url = new URL(xmlURL);
/* Get a SAXParser from the SAXPArserFactory. */
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
/* Get the XMLReader of the SAXParser we created. */
XMLReader xr = sp.getXMLReader();
/*
* Create a new ContentHandler and apply it to the
* XML-Reader
*/
xr.setContentHandler(myExampleHandler);
/* Parse the xml-data from our URL. */
xr.parse(new InputSource(url.openStream()));
/* Parsing has finished. */
/*
* Our ExampleHandler now provides the parsed data to
* us.
*/
ParsedExampleDataSet parsedExampleDataSet = myExampleHandler
.getParsedData();
} catch (Exception e) {
//showDialog(DIALOG_SEND_LOG);
}
}
}
private void getWallpaperThumb(){
int i = this.index;
if (!myExampleHandler.filenames.elementAt(i).toString().equalsIgnoreCase("")){
image = ImageOperations(context,
myExampleHandler.thumbs.elementAt(i).toString(), "image.jpg");
}
}
private void setWallpaperThumb(){
int i = this.index;
if (myExampleHandler.filenames.elementAt(i).toString() != null) {
String file_info = myExampleHandler.filenames.elementAt(i).toString();
String author = "\nby " + myExampleHandler.authors.elementAt(i).toString();
final String folder = myExampleHandler.folder_id.elementAt(folder_id).toString();
final String fid = myExampleHandler.fileid.elementAt(i).toString();
ImageView imgView = new ImageView(context);
TextView tv_filename = null;
TextView tv_author = null;
switch (i + 1) {
case 1:
imgView = (ImageView) findViewById(R.id.image1);
tv_filename = (TextView) findViewById(R.id.filename1);
tv_author = (TextView) findViewById(R.id.author1);
break;
case 2:
imgView = (ImageView) findViewById(R.id.image2);
tv_filename = (TextView) findViewById(R.id.filename2);
tv_author = (TextView) findViewById(R.id.author2);
break;
case 3:
imgView = (ImageView) findViewById(R.id.image3);
tv_filename = (TextView) findViewById(R.id.filename3);
tv_author = (TextView) findViewById(R.id.author3);
break;
case 4:
.
.
.
.
.
case 10:
imgView = (ImageView) findViewById(R.id.image10);
tv_filename = (TextView) findViewById(R.id.filename10);
tv_author = (TextView) findViewById(R.id.author10);
break;
}
if (image.getIntrinsicHeight() > 0) {
imgView.setImageDrawable(image);
} else {
imgView.setImageResource(R.drawable.default_wallpaper);
}
tv_filename.setText(file_info);
tv_author.setText(author);
imgView.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
// Perform action on click
}
});
}
}
private Drawable ImageOperations(Context ctx, String url,
String saveFilename) {
try {
InputStream is = (InputStream) this.fetch(url);
Drawable d = Drawable.createFromStream(is, "src");
return d;
} catch (MalformedURLException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
