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  • Representation of data in application versus database

    - by user1815201
    I'm going to make an application that will be given data to put in a database. The data will for the most part be the same, but the way it is formatted will vary a lot (could be in anything from text files to .xls to .doc). I'm not a very experienced developer, but I can see some potential issues and I want to minimize them. First off I have decided to use the DAO pattern, so that I can easily support new file formats or file suddenly formatted in different ways. What I really wonder about though, is how I should manage the data itself within my application. I'm thinking that the database DAO should have models representing each table of the database with the same relations between them, to make the uploading process easy. But should the filesystem DAO's have to use the same models? I can imaging that when the database changes, the change will suddenly propagate throughout the entire system, all DAOs and models alike. And that is obviously a bad thing. I'm a little bit tired and out of time. Will update with what ever questions you have. Thanks!

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  • Implementing MVC pattern in SWT application

    - by Pradeep Simha
    I am developing an SWT application (it's basically an Eclipse plugin, so I need to use SWT). Currently my design is as follows: Model: In model, I have POJOs which represents the actual fields in views. View: It is a dumb layer, it contains just UI and contains no logic (not even event handlers) Controller: It acts as a mediator b/w those two layers. Also it is responsible for creating view layer, handling events etc. Basically I have created all of the controls in view as a static like this public static Button btnLogin and in controller I have a code like this: public void createLoginView(Composite comp) { LoginFormView.createView(comp); //This createView method is in view layer ie LoginFormView LoginFormView.btnLogin.addSelectionListener(new SelectionListener() { //Code goes here }); } Similalrly I have done for other views and controls. So that in main class and other classes I am calling just createLoginView of controller. I am doing similar thing for other views. So my question, is what I am doing is correct? Is this design good? Or I should have followed any other approach. Since I am new to SWT and Eclipse plugin development (basically I am Java EE developer having 4+ years of exp). Any tips/pointers would be appreciated.

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  • How to get multiple open-source projects to use a standard way of doing something.

    - by Marco
    Problem In the last couple weeks, I've used 3 different "repository" tools (listed in alphabetical order): gradle ivy maven I'm calling them "repository" tools because I've also used sbt -- which fortunately uses ivy to manage it's cache or local repository. Each of these tools will create it's own repository. The defaults are: ~/.m2/repository for maven ~/.gradle/cache ~/.ivy2/cache Why can't they all use the same cache? Goal I'd like to change the world so that all three build tools could use the same cache. I'm looking for advice about issues I'm likely to run into and smart ways to get around them. By "use the same cache", I do not mean "retrieve from another build tool's cache". I mean "retrieve from and store in another build tool's cache". While I could go ahead and submit issues to the three projects, I know from experience (as a developer on an open source project), that if you want something done, you're best off getting it done yourself. Also, it seems like I need to get all 3 communities on board to some degree. What is the recommended approach for getting this kind of thing done? How do I approach the different communities? Do I work on patches for the 3 different projects, or would it be better off to create my own "interface" project that deals with these issues and have the 3 tools interface with that? Is this a standards question that I need to address on that front? Lastly, if I'm missing something and this is possible (in an globally configurable fashion), then please let me know.

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  • "Don't do programming after a few years of starting career". Is this a fair advice?

    - by Muhammad Yasir
    I am a little experienced developer having approximately 5 years experience in PHP and somewhat less in Java, C# and trying to learn some Python nowadays. Since the start of my career as a programmer I have been told every now and then by fellow programmers that programming is suitable for a few early years of a career (most of them take it as 5 years) and that one must change the direction after it. The reason they present include headaches and pressures associated with programming. They also say that programmers are less social and don't usually like to give time to their families, etc. and especially "Oh come on, you can not do programming your entire life!" I am somewhat confused here and need to ask others about it. If I leave programming then what do I do?! I guess teaching may be a good option in this case, but it will require to first earn a PhD degree perhaps. It may also be noteworthy that in my country (Pakistan) the life of a programmer is not very good in that normally they must give 2-3 extra hours in the office to accomplish urgent programming tasks. I have a sense that situation is somewhat similar in other countries and regions as well. Do you think it is fair advice to change career from programming to something else after spending 5 years in this field? UPDATE Oh wow... I never knew people can have 40+ years of experience in this field. I am both excited and amazed seeing that people are doing it since 1971... That means 15 years before my birth! It is nice to be able to talk to such experienced people, we don't get such a chance here in Pakistan.

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  • JEE frameworks, a road map to learn? and should I learn them?

    - by vibhor
    Background Information I have been into programming since past 1 years professionally, my day to day work includes writing BIRT reports, designing and validating forms using JEE (struts/spring, hibernate). I don't have a comp Sci 4 year degree (Electronics), so I have very Limited experience in comp Sci. Question JEE frameworks (struts1/2, spring, hibernate etc) are hot nowadays, however java world have a tendency of building A4j, B4J... mayway4J kind of stuff (and I am tired of it). AFAIK, frameworks are nothing but bunch of XML config files and hundreds of classes built to cram (by developer). And sooner then later a new framework come into picture that says I am the best among all. So My Question is - 1.What will you do to learn a framework (many frameworks) considering that it can be obsolete till you'll be master in it (Learning frameworks can take significant amount of time)? 2.Considering early into your career, will you give a damn that how well someone knows framework (knowing frame work is important but still..) and why/how should I learn a framework knowing I have to (un)learn it in order to learn other one (plenty of of 4Js....)? I am just trying to get a big picture, that, if you're in place of me, what would be your learning/cramming strategy (Road map)? I am not intended to start a holy war between A versus B, (frameworks are more or less essential).

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  • "Don't do programming after a few years of starting career" Is this a fair advice?

    - by Muhammad Yasir
    I am a little experienced developer having around 5 years experience in PHP and somewhat less in Java, C# and trying to learn some Python now a days. Since the start of my career as a programmer I have been told every now and then by fellow programmers that programming is suitable for a few early years of carrier (most of them take it as 5 years) and that one must change the direction after it. The reason they present is that headaches and pressures associated with programming. They also say that programmers are less social and don't usually like to give time to their families etc. and specially "Oh come on, you can not do programming in your entire life!" I am somewhat confused here and need to ask others about it. If I leave programming then what do I do?! I guess teaching may be a good option in this case but it will require to first earn a PhD degree perhaps. It may also be noteworthy that in my country (Pakistan) the life of a programmer is not very good in that normally they must give 2-3 extra hours in office to accomplish urgent programming tasks. I have a sense that situation is somewhat similar in other countries and regions as well. So the question is, do you think it is a fair advice to change career from programming to something else after spending 5 years in this field? Thanks for sharing thoughts!

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  • API Class with intensive network requests

    - by Marco Acierno
    I'm working an API which works as "intermediary" between a REST API and the developer. In this way, when the programmer do something like this: User user = client.getUser(nickname); it will execute a network request to download from the service the data about the user and then the programmer can use the data by doing things like user.getLocation(); user.getDisplayName(); and so on. Now there are some methods like getFollowers() which execute another network request and i could do it in two ways: Download all the data in the getUser method (and not only the most important) but in this way the request time could be very long since it should execute the request to various urls Download the data when the user calls the method, it looks like the best way and to improve it i could cache the result so the next call to getFollowers returns immediately with the data already download instead of execute again the request. What is the best way? And i should let methods like getUser and getFollowers stop the code execution until the data is ready or i should implement a callback so when the data is ready the callback gets fired? (this looks like Javascript)

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  • My first time in the gambling industry

    - by sfrj
    I am a Java enterprise developer with almost 3 years of professional experience. Soon i am going to have a face to face interview with a company in the gambling industry. I already did successfully a phone screening and now for the personal interview i suppose they will ask me about some kind of white board problem or system design task. I think i am in the right place to ask about this, and would appreciate a lot if someone would give me some tips or share something related to his own experience. The things i am more interested in regarding my interview are: What are the most common challenges for programmers, in this industry? Any idea or suggestion on a white board problem they may ask me? Could you point me to some links where i can find information on the topic or sample problems in this industry?. I personally find this question very interesting not just for me. Also i think, the given answers can help also others in a similar situation. Just what i want to say whit this last comment is: Please avoid, answers like: www.google.com and so on...

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  • I don't understand how TDD helps me get a good design if I need a design to start testing it

    - by Michael Stum
    I'm trying to wrap my head around TDD, specifically the development part. I've looked at some books, but the ones I found mainly tackle the testing part - the History of NUnit, why testing is good, Red/Green/Refactor and how to create a String Calculator. Good stuff, but that's "just" Unit Testing, not TDD. Specifically, I don't understand how TDD helps me get a good design if I need a Design to start testing it. To illustrate, imagine these 3 requirements: A catalog needs to have a list of products The catalog should remember which products a user viewed Users should be able to search for a product At this points, many books pull a magic rabbit out of a hat and just dive into "Testing the ProductService", but they don't explain how they came to the conclusion that there is a ProductService in the first place. That is the "Development" part in TDD that I'm trying to understand. There needs to be an existing design, but stuff outside of entity-services (that is: There is a Product, so there should be a ProductService) is nowhere to be found (e.g., the second requirement requires me to have some concept of a User, but where would I put the functionality to remind? And is Search a feature of the ProductService or a separate SearchService? How would I know which I should choose?) According to SOLID, I would need a UserService, but if I design a system without TDD, I might end up with a whole bunch of Single-Method Services. Isn't TDD intended to make me discover my design in the first place? I'm a .net developer, but Java resources would also work. I feel that there doesn't seem to be a real sample application or book that deals with a real line of business application. Can someone provide a clear example that illustrates the process of creating a design using TDD?

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  • How do I use Java to sort surnames in alphabetical order from file to file?

    - by user577939
    I have written this code and don't know how to sort surnames in alphabetical order from my file to another file. import java.io.*; import java.util.*; class Asmuo { String pavarde; String vardas; long buvLaikas; int atv1; int atv2; int atv3; } class Irasas { Asmuo duom; Irasas kitas; } class Sarasas { private Irasas p; Sarasas() { p = null; } Irasas itrauktiElementa(String pv, String v, long laikas, int d0, int d1, int d2) { String pvrd, vrd; int data0; int data1; int data2; long lks; lks = laikas; pvrd = pv; vrd = v; data0 = d0; data1 = d1; data2 = d2; Irasas r = new Irasas(); r.duom = new Asmuo(); uzpildymasDuomenimis(r, pvrd, vrd, lks, d0, d1, d2); r.kitas = p; p = r; return r; } void uzpildymasDuomenimis(Irasas r, String pv, String v, long laik, int d0, int d1, int d2) { r.duom.pavarde = pv; r.duom.vardas = v; r.duom.atv1 = d0; r.duom.buvLaikas = laik; r.duom.atv2 = d1; r.duom.atv3 = d2; } void spausdinti() { Irasas d = p; int i = 0; try { FileWriter fstream = new FileWriter("rez.txt"); BufferedWriter rez = new BufferedWriter(fstream); while (d != null) { System.out.println(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3); rez.write(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3 + "\n"); d = d.kitas; i++; } rez.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } } } public class Gyventojai { public static void main(String args[]) { Sarasas sar = new Sarasas(); Calendar atv = Calendar.getInstance(); Calendar isv = Calendar.getInstance(); try { FileInputStream fstream = new FileInputStream("duom.txt"); DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String eil; while ((eil = br.readLine()) != null) { String[] cells = eil.split(" "); String pvrd = cells[0]; String vrd = cells[1]; atv.set(Integer.parseInt(cells[2]), Integer.parseInt(cells[3]), Integer.parseInt(cells[4])); isv.set(Integer.parseInt(cells[5]), Integer.parseInt(cells[6]), Integer.parseInt(cells[7])); long laik = (isv.getTimeInMillis() - atv.getTimeInMillis()) / (24 * 60 * 60 * 1000); int d0 = Integer.parseInt(cells[2]); int d1 = Integer.parseInt(cells[3]); int d2 = Integer.parseInt(cells[4]); sar.itrauktiElementa(pvrd, vrd, laik, d0, d1, d2); } in.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } sar.spausdinti(); } }

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  • ORDER BY job failed in the Pig script while running EmbeddedPig using Java

    - by C.c. Huang
    I have this following pig script, which works perfectly using grunt shell (stored the results to HDFS without any issues); however, the last job (ORDER BY) failed if I ran the same script using Java EmbeddedPig. If I replace the ORDER BY job by others, such as GROUP or FOREACH GENERATE, the whole script then succeeded in Java EmbeddedPig. So I think it's the ORDER BY which causes the issue. Anyone has any experience with this? Any help would be appreciated! The Pig script: REGISTER pig-udf-0.0.1-SNAPSHOT.jar; user_similarity = LOAD '/tmp/sample-sim-score-results-31/part-r-00000' USING PigStorage('\t') AS (user_id: chararray, sim_user_id: chararray, basic_sim_score: float, alt_sim_score: float); simplified_user_similarity = FOREACH user_similarity GENERATE $0 AS user_id, $1 AS sim_user_id, $2 AS sim_score; grouped_user_similarity = GROUP simplified_user_similarity BY user_id; ordered_user_similarity = FOREACH grouped_user_similarity { sorted = ORDER simplified_user_similarity BY sim_score DESC; top = LIMIT sorted 10; GENERATE group, top; }; top_influencers = FOREACH ordered_user_similarity GENERATE com.aol.grapevine.similarity.pig.udf.AssignPointsToTopInfluencer($1, 10); all_influence_scores = FOREACH top_influencers GENERATE FLATTEN($0); grouped_influence_scores = GROUP all_influence_scores BY bag_of_topSimUserTuples::user_id; influence_scores = FOREACH grouped_influence_scores GENERATE group AS user_id, SUM(all_influence_scores.bag_of_topSimUserTuples::points) AS influence_score; ordered_influence_scores = ORDER influence_scores BY influence_score DESC; STORE ordered_influence_scores INTO '/tmp/cc-test-results-1' USING PigStorage(); The error log from Pig: 12/04/05 10:00:56 INFO pigstats.ScriptState: Pig script settings are added to the job 12/04/05 10:00:56 INFO mapReduceLayer.JobControlCompiler: mapred.job.reduce.markreset.buffer.percent is not set, set to default 0.3 12/04/05 10:00:58 INFO mapReduceLayer.JobControlCompiler: Setting up single store job 12/04/05 10:00:58 INFO jvm.JvmMetrics: Cannot initialize JVM Metrics with processName=JobTracker, sessionId= - already initialized 12/04/05 10:00:58 INFO mapReduceLayer.MapReduceLauncher: 1 map-reduce job(s) waiting for submission. 12/04/05 10:00:58 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same. 12/04/05 10:00:58 INFO input.FileInputFormat: Total input paths to process : 1 12/04/05 10:00:58 INFO util.MapRedUtil: Total input paths to process : 1 12/04/05 10:00:58 INFO util.MapRedUtil: Total input paths (combined) to process : 1 12/04/05 10:00:58 INFO filecache.TrackerDistributedCacheManager: Creating tmp-1546565755 in /var/lib/hadoop-0.20/cache/cchuang/mapred/local/archive/4334795313006396107_361978491_57907159/localhost/tmp/temp1725960134-work-6955502337234509704 with rwxr-xr-x 12/04/05 10:00:58 INFO filecache.TrackerDistributedCacheManager: Cached hdfs://localhost/tmp/temp1725960134/tmp-1546565755#pigsample_854728855_1333645258470 as /var/lib/hadoop-0.20/cache/cchuang/mapred/local/archive/4334795313006396107_361978491_57907159/localhost/tmp/temp1725960134/tmp-1546565755 12/04/05 10:00:58 INFO filecache.TrackerDistributedCacheManager: Cached hdfs://localhost/tmp/temp1725960134/tmp-1546565755#pigsample_854728855_1333645258470 as /var/lib/hadoop-0.20/cache/cchuang/mapred/local/archive/4334795313006396107_361978491_57907159/localhost/tmp/temp1725960134/tmp-1546565755 12/04/05 10:00:58 WARN mapred.LocalJobRunner: LocalJobRunner does not support symlinking into current working dir. 12/04/05 10:00:58 INFO mapred.TaskRunner: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/local/archive/4334795313006396107_361978491_57907159/localhost/tmp/temp1725960134/tmp-1546565755 <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/pigsample_854728855_1333645258470 12/04/05 10:00:58 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/.job.jar.crc <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/.job.jar.crc 12/04/05 10:00:58 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/.job.split.crc <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/.job.split.crc 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/.job.splitmetainfo.crc <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/.job.splitmetainfo.crc 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/.job.xml.crc <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/.job.xml.crc 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/job.jar <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/job.jar 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/job.split <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/job.split 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/job.splitmetainfo <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/job.splitmetainfo 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Creating symlink: /var/lib/hadoop-0.20/cache/cchuang/mapred/staging/cchuang402164468/.staging/job_local_0004/job.xml <- /var/lib/hadoop-0.20/cache/cchuang/mapred/local/localRunner/job.xml 12/04/05 10:00:59 INFO mapred.Task: Using ResourceCalculatorPlugin : null 12/04/05 10:00:59 INFO mapred.MapTask: io.sort.mb = 100 12/04/05 10:00:59 INFO mapred.MapTask: data buffer = 79691776/99614720 12/04/05 10:00:59 INFO mapred.MapTask: record buffer = 262144/327680 12/04/05 10:00:59 WARN mapred.LocalJobRunner: job_local_0004 java.lang.RuntimeException: org.apache.hadoop.mapreduce.lib.input.InvalidInputException: Input path does not exist: file:/Users/cchuang/workspace/grapevine-rec/pigsample_854728855_1333645258470 at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.partitioners.WeightedRangePartitioner.setConf(WeightedRangePartitioner.java:139) at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:62) at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117) at org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:560) at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:639) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:323) at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:210) Caused by: org.apache.hadoop.mapreduce.lib.input.InvalidInputException: Input path does not exist: file:/Users/cchuang/workspace/grapevine-rec/pigsample_854728855_1333645258470 at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.listStatus(FileInputFormat.java:231) at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigFileInputFormat.listStatus(PigFileInputFormat.java:37) at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.getSplits(FileInputFormat.java:248) at org.apache.pig.impl.io.ReadToEndLoader.init(ReadToEndLoader.java:153) at org.apache.pig.impl.io.ReadToEndLoader.<init>(ReadToEndLoader.java:115) at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.partitioners.WeightedRangePartitioner.setConf(WeightedRangePartitioner.java:112) ... 6 more 12/04/05 10:00:59 INFO filecache.TrackerDistributedCacheManager: Deleted path /var/lib/hadoop-0.20/cache/cchuang/mapred/local/archive/4334795313006396107_361978491_57907159/localhost/tmp/temp1725960134/tmp-1546565755 12/04/05 10:00:59 INFO mapReduceLayer.MapReduceLauncher: HadoopJobId: job_local_0004 12/04/05 10:01:04 INFO mapReduceLayer.MapReduceLauncher: job job_local_0004 has failed! Stop running all dependent jobs 12/04/05 10:01:04 INFO mapReduceLayer.MapReduceLauncher: 100% complete 12/04/05 10:01:04 ERROR pigstats.PigStatsUtil: 1 map reduce job(s) failed! 12/04/05 10:01:04 INFO pigstats.PigStats: Script Statistics: HadoopVersion PigVersion UserId StartedAt FinishedAt Features 0.20.2-cdh3u3 0.8.1-cdh3u3 cchuang 2012-04-05 10:00:34 2012-04-05 10:01:04 GROUP_BY,ORDER_BY Some jobs have failed! Stop running all dependent jobs Job Stats (time in seconds): JobId Maps Reduces MaxMapTime MinMapTIme AvgMapTime MaxReduceTime MinReduceTime AvgReduceTime Alias Feature Outputs job_local_0001 0 0 0 0 0 0 0 0 all_influence_scores,grouped_user_similarity,simplified_user_similarity,user_similarity GROUP_BY job_local_0002 0 0 0 0 0 0 0 0 grouped_influence_scores,influence_scores GROUP_BY,COMBINER job_local_0003 0 0 0 0 0 0 0 0 ordered_influence_scores SAMPLER Failed Jobs: JobId Alias Feature Message Outputs job_local_0004 ordered_influence_scores ORDER_BY Message: Job failed! Error - NA /tmp/cc-test-results-1, Input(s): Successfully read 0 records from: "/tmp/sample-sim-score-results-31/part-r-00000" Output(s): Failed to produce result in "/tmp/cc-test-results-1" Counters: Total records written : 0 Total bytes written : 0 Spillable Memory Manager spill count : 0 Total bags proactively spilled: 0 Total records proactively spilled: 0 Job DAG: job_local_0001 -> job_local_0002, job_local_0002 -> job_local_0003, job_local_0003 -> job_local_0004, job_local_0004 12/04/05 10:01:04 INFO mapReduceLayer.MapReduceLauncher: Some jobs have failed! Stop running all dependent jobs

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  • How does java.util.Collections.contains() perform faster than a linear search?

    - by The111
    I've been fooling around with a bunch of different ways of searching collections, collections of collections, etc. Doing lots of stupid little tests to verify my understanding. Here is one which boggles me (source code further below). In short, I am generating N random integers and adding them to a list. The list is NOT sorted. I then use Collections.contains() to look for a value in the list. I intentionally look for a value that I know won't be there, because I want to ensure that the entire list space is probed. I time this search. I then do another linear search manually, iterating through each element of the list and checking if it matches my target. I also time this search. On average, the second search takes 33% longer than the first one. By my logic, the first search must also be linear, because the list is unsorted. The only possibility I could think of (which I immediately discard) is that Java is making a sorted copy of my list just for the search, but (1) I did not authorize that usage of memory space and (2) I would think that would result in MUCH more significant time savings with such a large N. So if both searches are linear, they should both take the same amount of time. Somehow the Collections class has optimized this search, but I can't figure out how. So... what am I missing? import java.util.*; public class ListSearch { public static void main(String[] args) { int N = 10000000; // number of ints to add to the list int high = 100; // upper limit for random int generation List<Integer> ints; int target = -1; // target will not be found, forces search of entire list space long start; long end; ints = new ArrayList<Integer>(); start = System.currentTimeMillis(); System.out.print("Generating new list... "); for (int i = 0; i < N; i++) { ints.add(((int) (Math.random() * high)) + 1); } end = System.currentTimeMillis(); System.out.println("took " + (end-start) + "ms."); start = System.currentTimeMillis(); System.out.print("Searching list for target (method 1)... "); if (ints.contains(target)) { // nothing } end = System.currentTimeMillis(); System.out.println(" Took " + (end-start) + "ms."); System.out.println(); ints = new ArrayList<Integer>(); start = System.currentTimeMillis(); System.out.print("Generating new list... "); for (int i = 0; i < N; i++) { ints.add(((int) (Math.random() * high)) + 1); } end = System.currentTimeMillis(); System.out.println("took " + (end-start) + "ms."); start = System.currentTimeMillis(); System.out.print("Searching list for target (method 2)... "); for (Integer i : ints) { // nothing } end = System.currentTimeMillis(); System.out.println(" Took " + (end-start) + "ms."); } }

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  • Need to find jni.h in cmake on Mac

    - by Ilan Tal
    I am trying to make VTK compile on a Mac Air machine. I am using CMake 2.8-9, using Xcode4 as the generator. If I press the Configure button with VTK_WRAP_JAVA not checked, it will go with no errors. However I definitely need to use the wrap java since my main program is in Java and I need to get to VTK which is c++. As soon as I check the wrap Java, I get Could NOT find JNI. It apparently is looking for jni.h which in Linux there is no problem finding, but in the Mac it apparently can't find it. I did a locate jni.h and got new-host-2:~ geraldkolodny$ locate jni.h /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk/System/Library/Frameworks/JavaVM.framework/Versions/A/Headers/jni.h /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk/System/Library/Frameworks/JavaVM.framework/Versions/A/Headers/jni.h /Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home/include/jni.h I tried to manually put into JAVA_INCLUDE_PATH2 either entry 2 or 3 (without the jni.h at the end), but it still can't find jni.h. Xcode used to have a template for jni but that is now gone in the latest version. I am fresh out of ideas on how to solve this problem. I'd be grateful for any suggestions. Thanks, Ilan

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  • eclipse IDE won't start in ubuntu 10.04 64bit with sun-java

    - by aeischeid
    i get this error when I try to run from CLI ** (Eclipse:2318): CRITICAL **: menu_proxy_module_load: assertion `dbusproxy != NULL' failed # A fatal error has been detected by the Java Runtime Environment: # SIGSEGV (0xb) at pc=0x00007f34511a4e74, pid=2318, tid=139863603410704 # JRE version: 6.0_18-b18 Java VM: OpenJDK 64-Bit Server VM (14.0-b16 mixed mode linux-amd64 ) Derivative: IcedTea6 1.8 Distribution: Ubuntu lucid (development branch), package 6b18-1.8-0ubuntu1 Problematic frame: C [libglib-2.0.so.0+0x41e74] g_main_context_prepare+0x164 # An error report file with more information is saved as: /home/aaron/opt/eclipse/hs_err_pid2318.log # If you would like to submit a bug report, please include instructions how to reproduce the bug and visit: https://bugs.launchpad.net/ubuntu/+source/openjdk-6/ The crash happened outside the Java Virtual Machine in native code. See problematic frame for where to report the bug. # I have sun-java installed and set in my PATH: ~: echo $JAVA_HOME /usr/lib/jvm/java-6-sun/

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  • Better way to get int from FragmentActivity in a Fragment?

    - by Gimberg
    Hi im trying to get an int from my FragmentActivity and i have a way to do this but the code get very cluttered and long and i did this to shorten the problem and i don't get any errors while in the editor but when i run the app it eminently crashes. Any suggestions? An example of the code that doesn't work MainActivity mainActivity = ((MainActivity)getActivity()); public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.upgrades_fragment, container, false); TextView AirFreshenersCost = (TextView) view.findViewById(R.id.AirFreshenersCost ); if(mainActivity.amountAirFresheners == 5){ AirFreshenersCost.setText("5"); } return view; } LogCat 10-27 22:16:37.333: E/AndroidRuntime(5593): FATAL EXCEPTION: main 10-27 22:16:37.333: E/AndroidRuntime(5593): java.lang.NullPointerException 10-27 22:16:37.333: E/AndroidRuntime(5593): at com.free.dennisg.clickingbad.fragments.UpgradesFragment.onCreateView(UpgradesFragment.java:40) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.view.ViewPager.populate(ViewPager.java:1068) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.view.ViewPager.populate(ViewPager.java:914) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.support.v4.view.ViewPager$3.run(ViewPager.java:244) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.view.Choreographer.doFrame(Choreographer.java:531) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.os.Handler.handleCallback(Handler.java:730) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.os.Handler.dispatchMessage(Handler.java:92) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.os.Looper.loop(Looper.java:137) 10-27 22:16:37.333: E/AndroidRuntime(5593): at android.app.ActivityThread.main(ActivityThread.java:5289) 10-27 22:16:37.333: E/AndroidRuntime(5593): at java.lang.reflect.Method.invokeNative(Native Method) 10-27 22:16:37.333: E/AndroidRuntime(5593): at java.lang.reflect.Method.invoke(Method.java:525) 10-27 22:16:37.333: E/AndroidRuntime(5593): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739) 10-27 22:16:37.333: E/AndroidRuntime(5593): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555) 10-27 22:16:37.333: E/AndroidRuntime(5593): at dalvik.system.NativeStart.main(Native Method) An example of the code that work public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.upgrades_fragment, container, false); TextView AirFreshenersCost = (TextView) view.findViewById(R.id.AirFreshenersCost ); if(((MainActivity)getActivity()).amountAirFresheners == 5){ AirFreshenersCost.setText("5"); } return view; }

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  • Grails: GGTS not running on Amazon AWS EC2 anyone else successful?

    - by Anonymous Human
    Im just curious if anyone has had success trying to run the Groovy Grails tool suite on an Amazon AWS EC2 instance with its display exported into your windows machine. If so, I wanted to know which flavor of linux was used on the EC2. I am not having much success with it on the Amazon Linux but haven't tried their Ubuntu instances yet. I got all the way to getting GGTS installed and getting the display exported but when I launch GGTS I get log errors about libraries missing. This is most likely because I didn't use yum to install it so I am probably missing dependencies but I didn't have a choice its not offered as a yum package. Here are my log file errors when I try to launch GGTS: !SESSION 2014-06-08 03:08:04.873 ----------------------------------------------- eclipse.buildId=3.5.1.201405030657-RELEASE-e43 java.version=1.7.0_55 java.vendor=Oracle Corporation Framework arguments: -product org.springsource.ggts.ide Command-line arguments: -os linux -ws gtk -arch x86_64 -product org.springsourc e.ggts.ide !ENTRY org.eclipse.osgi 4 0 2014-06-08 03:08:12.116 !MESSAGE Application error !STACK 1 java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: /home/ec2-user/ggts_sh/ggts-3.5.1.RELEASE/configuration/org.eclipse.osgi /bundles/704/1/.cp/libswt-pi-gtk-4335.so: libgtk-x11-2.0.so.0: cannot open share d object file: No such file or directory no swt-pi-gtk in java.library.path /home/ec2-user/.swt/lib/linux/x86_64/libswt-pi-gtk-4335.so: libgtk-x11-2 .0.so.0: cannot open shared object file: No such file or directory Can't load library: /home/ec2-user/.swt/lib/linux/x86_64/libswt-pi-gtk.s o at org.eclipse.swt.internal.Library.loadLibrary(Library.java:331) at org.eclipse.swt.internal.Library.loadLibrary(Library.java:240) at org.eclipse.swt.internal.gtk.OS.<clinit>(OS.java:45) at org.eclipse.swt.internal.Converter.wcsToMbcs(Converter.java:63) at org.eclipse.swt.internal.Converter.wcsToMbcs(Converter.java:54) at org.eclipse.swt.widgets.Display.<clinit>(Display.java:133) at org.eclipse.ui.internal.Workbench.createDisplay(Workbench.java:679) at org.eclipse.ui.PlatformUI.createDisplay(PlatformUI.java:162) at org.eclipse.ui.internal.ide.application.IDEApplication.createDisplay( IDEApplication.java:154) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEAppli cation.java:96) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandl e.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runAppli cation(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(Ec lipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.ja va:354) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.ja va:181) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl. java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces sorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:636) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:591) at org.eclipse.equinox.launcher.Main.run(Main.java:1450) at org.eclipse.equinox.launcher.Main.main(Main.java:1426)

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  • Swing: How do I run a job from AWT thread, but after a window was layed out?

    - by java.is.for.desktop
    My complete GUI runs inside the AWT thread, because I start the main window using SwingUtilities.invokeAndWait(...). Now I have a JDialog which has just to display a JLabel, which indicates that a certain job is in progress, and close that dialog after the job was finished. The problem is: the label is not displayed. That job seems to be started before JDialog was fully layed-out. When I just let the dialog open without waiting for a job and closing, the label is displayed. The last thing the dialog does in its ctor is setVisible(true). Things such as revalidate(), repaint(), ... don't help either. Even when I start a thread for the monitored job, and wait for it using someThread.join() it doesn't help, because the current thread (which is the AWT thread) is blocked by join, I guess. Replacing JDialog with JFrame doesn't help either. So, is the concept wrong in general? Or can I manage it to do certain job after it is ensured that a JDialog (or JFrame) is fully layed-out? Simplified algorithm of what I'm trying to achieve: Create a subclass of JDialog Ensure that it and its contents are fully layed-out Start a process and wait for it to finish (threaded or not, doesn't matter) Close the dialog I managed to write a reproducible test case: EDIT Problem from an answer is now addressed: This use case does display the label, but it fails to close after the "simulated process", because of dialog's modality. import java.awt.*; import javax.swing.*; public class _DialogTest2 { public static void main(String[] args) throws Exception { SwingUtilities.invokeAndWait(new Runnable() { final JLabel jLabel = new JLabel("Please wait..."); @Override public void run() { JFrame myFrame = new JFrame("Main frame"); myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); myFrame.setSize(750, 500); myFrame.setLocationRelativeTo(null); myFrame.setVisible(true); JDialog d = new JDialog(myFrame, "I'm waiting"); d.setModalityType(Dialog.ModalityType.APPLICATION_MODAL); d.add(jLabel); d.setSize(300, 200); d.setLocationRelativeTo(null); d.setVisible(true); SwingUtilities.invokeLater(new Runnable() { @Override public void run() { try { Thread.sleep(3000); // simulate process jLabel.setText("Done"); } catch (InterruptedException ex) { } } }); d.setVisible(false); d.dispose(); myFrame.setVisible(false); myFrame.dispose(); } }); } }

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  • I need to take an array of three lines in a text file and sort them base on the first line in Java.

    - by Cory
    I need to take an array of three lines in a text file and sort them base on the first line in Java. I also need to manipulate this as well and then print to screen. I have a test file that is formatted like this: 10 Michael Jackson 12 Richard Woolsey I need to input this from a text file and then rearrange it based on the number associated with the name. At that point, I need to use a random number generator and assign a variable based on the random number to each name. Then I need to print to screen the variable I added and the name in a different format. Here is an example of the output: 12: Woolsey, Richard Variable assigned 10: Jackson, Michael Other variable assigned I highly appreciate any help. I ask because I do not really know how to input the three lines as one variable and then manipulate later on in the program. Thanks, Cory

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  • Are you as productive in Javascript as you are in .Net or Java?

    - by bglenn
    I code primarily in javascript and in vb.net. I've found that if I can achieve the same thing in both javascript and vb.net that I feel far more productive and expressive using javascript for the task. I often find myself researching server-side javascript implementations to see if anything has gone mainstream so that I can code my back-end business logic and data access in javascript. Given all the advanced tooling and language features in .Net this preference seems somewhat paradoxical to me. I'm not suggesting one is better than the other (I've been a vb programmer since I started programming), I'm just wondering if my preference is entirely subjective or if anyone else shares it. So, does anyone else enjoy coding in javascript to the point where you prefer it to the .Net and Java environment, and if, so why?

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  • How to automatically add SVN commit messages and revision numbering to java file?

    - by John
    I'm working on an Apache Wicket project in Eclipse with Maven2 -- my SCM is Subversion. I've got Subclipse set up which I use to commit changes to the repository. I've seen several projects with nice headers containing the current revision number and at the bottom of the java source file there's a list of all the changes that have been committed to the file including the comments that were passed. Is there any way of achieving this sort of behaviour automatically? At work I'm using MKS which does this automatically but I am yet to figure out how to achieve this with SVN and Eclipse.

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  • java.lang.IllegalStateException: Parent was not null, but this component not related

    - by Muneeswaran Balasubramanian
    Hi to all, I have the following exception at the time of running jsf program. org.apache.jasper.JasperException: An exception occurred processing JSP page /pages/general/internalServerErrorPage.jsp at line 44 41: <link rel="shortcut icon" href="<%=request.getContextPath()%>/resources/images/infomindzicon.ico" type="image/x-icon" /> 42: </head> 43: <body id="sscmsMainBody"> 44: <h:form id="internalServerErrorPageForm" binding="#{ServerErrorBean.initForm}"> 45: <rich:page id="richPage" theme="#{LayoutSkinBean.layoutTheme}" 46: width="#{LayoutSkinBean.layoutScreenWidth}" 47: sidebarWidth="0"> Caused by: javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.IllegalStateException: Parent was not null, but this component not related at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:858) at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791) at org.apache.jsp.pages.general.internalServerErrorPage_jsp._jspService(internalServerErrorPage_jsp.java:207) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377) What is the meaning of this exception and how can i resolve this?Please help me.Thanks in advance.

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  • Ever any performance different between Java >> and >>> right shift operators?

    - by Sean Owen
    Is there ever reason to think the (signed) and (unsigned) right bit-shift operators in Java would perform differently? I can't detect any difference on my machine. This is purely an academic question; it's never going to be the bottleneck I'm sure. I know: it's best to write what you mean foremost; use for division by 2, for example. I assume it comes down to which architectures have which operations implemented as an instruction.

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  • How to download a file from a server using Java Socket?

    - by Ada
    Hi, I have an assignment about uploading and downloading a file to a server. I managed to do the uploading part using Java Sockets however I am having a hard time doing the downloading part. I should use Range: for downloading parellel. In my request, I should have the Range: header. But I don't understand how I will receive the file with that HTTP GET request. All the examples I have seen was about uploading a file. I already did it. I can upload .exe, image, .pdf, anything and when I download them back (by my browser), there are no errors. Can you help me with the downloading part? Can you give me an example beacuse I really didn't get it.

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  • How to convert a Java object (bean) to key-value pairs (and vice versa)?

    - by Shahbaz
    Say I have a very simple java object that only has some getXXX and setXXX properties. This object is used only to handle values, basically a record or a type-safe (and performant) map. I often need to covert this object to key value pairs (either strings or type safe) or convert from key value pairs to this object. Other than reflection or manually writing code to do this conversion, what is the best way to achieve this? An example might be sending this object over jms, without using the ObjectMessage type (or converting an incoming message to the right kind of object).

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