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unable to compile a servlet in ubuntu

- by codeomnitrix

I am newbie to j2ee. I have download and installed j2eesdk-1_4_03-linux.bin in my ubuntu 10.04 distribution. and then i tried to code my first servlet in it as: import java.io.*; import javax.servelet.*; import javax.servelet.http.*; public class HowdyServelet extends HttpServelet{ public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ PrintWriter out = response.getWriter(); response.setContentType("text/html"); out.println("<html>"); out.println("<head><title>howdy</title></head>"); out.println("<body>"); out.println("<center><h1>Howdy</h1></center>"); out.println("</body>"); out.println("</html>"); } } and here are the environment variables i set after installation: 1. J2EE_HOME=/home/vinit/SUNWappserver 2. JAVA_HOME=/home/vinit/SUNWappserver/jdk 3. CLASSPATH=/home/vinit/SUNWappserver/lib and now i tried to compile the servlet using javac HowdyServelet.java But i got following errors: HowdyServelet.java:2: package javax.servelet does not exist import javax.servelet.*; ^ HowdyServelet.java:3: package javax.servelet.http does not exist import javax.servelet.http.*; ^ HowdyServelet.java:5: cannot find symbol symbol: class HttpServelet public class HowdyServelet extends HttpServelet{ ^ HowdyServelet.java:6: cannot find symbol symbol : class HttpServeletRequest location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ HowdyServelet.java:6: cannot find symbol symbol : class HttpServeletResponse location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ HowdyServelet.java:6: cannot find symbol symbol : class ServeletException location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ 6 errors So how to compile this servlet. Thanks in advance.

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using switch in strings

- by xtemer

guys me trying to use switch in strings by first coverting string into char and then apply switch but still didnt done it....here is my code..help me out.. import javax.swing.*; import java.io.*; class HappyBirthday { public static void main(String[] args) throws IOException { String Month; char[] Months = Month.toCharArray(); BufferedReader dataIn= new BufferedReader(new InputStreamReader(System.in)); System.out.println("Please enter your month."); Month = JOptionPane.showInputDialog("enter month"); String month1={"January","feb"}; char[] month2 = month1.toCharArray(); // String s=month1.equals(Month); //System.out.print(month2Array[0]); switch (month2) { case 0: System.out.println("kool"); break; case 1: System.out.println("not kool"); break; default: }}} /** if (month1[1].equals(Month)) System.out.println("kool"); else if(month1[0].equals(Month)) System.out.println("kooooooooooooool"); else System.out.println("Big kooooool"); **/

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Refresher on Java classes in separate files

- by JohnFaig

I need a refresher on moving classes from one file into two files. My sample code is in one file called "external_class_file_main". The program runs fine and the code is shown below: Public class external_class_file_main { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } I move the get_a_random_number class to a separate file called "external_class_file". When I do this, I get the following error: Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method get_a_random_number(int, int) is undefined for the type external_class_file_main at external_class_file_main.main(external_class_file_main.java:20) The "external_class_file_main" now contains: public class external_class_file_main { public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } The "external_class_file" now contains: public class external_class_file { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } }

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to connect matlab with java

- by user304005

Through the below given code I was able to connect to matlab. But I was not able to execute the script file containing matlab code...Please help me to modify the code so as to execute the matlab code.... Here luck2 is a .m file.... import java.io.InputStreamReader; import java.io.*; public class matlab { private static File myMATLABScript; public static String runScript(File luck2) { String output = "" ; String error = ""; try { String commandToRun ="C:\\Program Files\\MATLAB\\R2009a\\bin\\matlab -nodisplay <" + "Z:\\sem\\java\\luck2"; //String commandToRun = "matlab -nosplash -r myMATLABScript -nodisplay -nodesktop < " + opentxt; System.out.println(commandToRun); Process p = Runtime.getRuntime().exec(commandToRun); String s; BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream())); BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream())); System.out.println("\nHere is the standard output of the command:\n"); while ((s = stdInput.readLine()) != null) { System.out.println("haiiiiiiiiiiii"); output = s + "\n"; System.out.println(s); } while ((s = stdError.readLine()) != null) { error = s + "\n"; System.out.println(s); } } catch (Exception e) { System.out.println("exception happened here what I know:"); e.printStackTrace(); System.exit(-1); } return output + error; } public static void main(String[] args) throws IOException { matlab m = new matlab(); matlab.runScript(myMATLABScript); //matlab.runScript(); } }

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When do instance variables get initialized and values assigned?

- by AKh

When doees the instance variable get initialized? Is it after the constructor block is done or before it? Consider this example: public abstract class Parent { public Parent(){ System.out.println("Parent Constructor"); init(); } public void init(){ System.out.println("parent Init()"); } } public class Child extends Parent { private Integer attribute1; private Integer attribute2 = null; public Child(){ super(); System.out.println("Child Constructor"); } public void init(){ System.out.println("Child init()"); super.init(); attribute1 = new Integer(100); attribute2 = new Integer(200); } public void print(){ System.out.println("attribute 1 : " +attribute1); System.out.println("attribute 2 : " +attribute2); } } public class Tester { public static void main(String[] args) { Parent c = new Child(); ((Child)c).print(); } } OUTPUT: Parent Constructor Child init() parent Init() Child Constructor attribute 1 : 100 attribute 2 : null When the memory for the atribute 1 & 2 are allocated in the heap ? Curious to know why is attribute 2 is NULL ? Are there any design flaws?

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Java InputStream encoding/charset

- by Tobbe

Running the following (example) code import java.io.*; public class test { public static void main(String[] args) throws Exception { byte[] buf = {-27}; InputStream is = new ByteArrayInputStream(buf); BufferedReader r = new BufferedReader(new InputStreamReader(is, "ISO-8859-1")); String s = r.readLine(); System.out.println("test.java:9 [byte] (char)" + (char)s.getBytes()[0] + " (int)" + (int)s.getBytes()[0]); System.out.println("test.java:10 [char] (char)" + (char)s.charAt(0) + " (int)" + (int)s.charAt(0)); System.out.println("test.java:11 string below"); System.out.println(s); System.out.println("test.java:13 string above"); } } gives me this output test.java:9 [byte] (char)? (int)63 test.java:10 [char] (char)? (int)229 test.java:11 string below ? test.java:13 string above How do I retain the correct byte value (-27) in the line-9 printout? And consequently receive the expected output of the System.out.println(s) command (å).

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Values are not returning from MY SQL database to my java class

- by sam

Hi, This is my Query DELIMITER $$ DROP PROCEDURE IF EXISTSdiscoverdb.getuser_info$$ # MySQL returned an empty result set (i.e. zero rows). `CREATE PROCEDURE discoverdb.getuser_info ( IN name VARCHAR(100), IN pass VARCHAR(100) ) BEGIN SELECT * FROM ad_user WHERE sLogin = name AND sPassHash=password(pass); END $$ # MySQL returned an empty result set (i.e. zero rows). DELIMITER ; This is my calling method public Authentication getAuthentication (String username,String password) { //TODO write your implementation code here: Authentication ack = new Authentication(); try{ String simpleProc = "{ call getuser_infosam(?,?)}"; java.sql.CallableStatement cs = con.prepareCall(simpleProc); cs.setString(1, username); cs.setString(2, password); java.sql.ResultSet rs = cs.executeQuery(); while (rs.next()) { System.out.println(rs.getString("sLogin")); System.out.println(rs.getString("sPassHash")); System.out.println(rs.getString("sForename")); System.out.println(rs.getString("sName")); System.out.println(rs.getString("company")); System.out.println(rs.getString("sEmail")); rs.close();} }catch ( Exception e) { e.printStackTrace(); System.out.print(e); } return ack; }

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getSystemResourceAsStream() returns null

- by Hitesh Solanki

Hiii... I want to get the content of properties file into InputStream class object using getSystemResourceAsStream(). I have built the sample code. It works well using main() method,but when i deploy the project and run on the server, properties file path cannot obtained ... so inputstream object store null value. Sample code is here.. public class ReadPropertyFromFile { public static Logger logger = Logger.getLogger(ReadPropertyFromFile.class); public static String readProperty(String fileName, String propertyName) { String value = null; try { //fileName = "api.properties"; //propertyName = "api_loginid"; System.out.println("11111111...In the read proprty file....."); // ClassLoader loader = ClassLoader.getSystemClassLoader(); InputStream inStream = ClassLoader.getSystemResourceAsStream(fileName); System.out.println("In the read proprty file....."); System.out.println("File Name :" + fileName); System.out.println("instream = "+inStream); Properties prop = new Properties(); try { prop.load(inStream); value = prop.getProperty(propertyName); } catch (Exception e) { logger.warn("Error occured while reading property " + propertyName + " = ", e); return null; } } catch (Exception e) { System.out.println("Exception = " + e); } return value; } public static void main(String args[]) { System.out.println("prop value = " + ReadPropertyFromFile.readProperty("api.properties", "api_loginid")); } }

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String doesn't match regex when read from keyboard.

- by athspk

public static void main(String[] args) throws IOException { String str1 = "??123456"; System.out.println(str1+"-"+str1.matches("^\\p{InGreek}{2}\\d{6}")); //??123456-true BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String str2 = br.readLine(); //??123456 same as str1. System.out.println(str2+"-"+str2.matches("^\\p{InGreek}{2}\\d{6}")); //?”??123456-false System.out.println(str1.equals(str2)); //false } The same String doesn't match regex when read from keyboard. What causes this problem, and how can we solve this? Thanks in advance. EDIT: I used System.console() for input and output. public static void main(String[] args) throws IOException { PrintWriter pr = System.console().writer(); String str1 = "??123456"; pr.println(str1+"-"+str1.matches("^\\p{InGreek}{2}\\d{6}")+"-"+str1.length()); String str2 = System.console().readLine(); pr.println(str2+"-"+str2.matches("^\\p{InGreek}{2}\\d{6}")+"-"+str2.length()); pr.println("str1.equals(str2)="+str1.equals(str2)); } Output: ??123456-true-8 ??123456 ??123456-true-8 str1.equals(str2)=true

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When Creating a Reference for an Object Where from where that class is Loaded?

- by asela38

When doing some sample codings with Java I came crosss ClassCast Exception, from where I cast the object to StaticClass. Can any explaing the what has happened here. public void test5() throws Exception { System.out.println(StaticClass.obj); Object newInstance = ClassLoader.getSystemClassLoader().loadClass("com.StaticClass").newInstance(); System.out.println(newInstance.getClass().getDeclaredField("obj").get(newInstance)); Object newInstance2 = new ILoader().loadClass("com//StaticClass.class").newInstance(); System.out.println(newInstance2.getClass().getDeclaredField("obj").get(newInstance2)); StaticClass s = (StaticClass)newInstance2; System.out.println(s.obj); System.out.println(newInstance.getClass().getClassLoader()); System.out.println(newInstance2.getClass().getClassLoader()); } package com; public class StaticClass { public static final Object obj = new Object(); } package com; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class ILoader extends ClassLoader { public ILoader() { super(null); } @Override protected Class<?> findClass(String name) throws ClassNotFoundException { File file = new File(name); byte[] bytes = new byte[(int)file.length()]; try { new FileInputStream(file).read(bytes); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return super.defineClass("com.StaticClass",bytes, 0, bytes.length); } } output which was given by last sysout's when the casting part of the code not existed is as belows. sun.misc.Launcher$AppClassLoader@133056f com.ILoader@1ac3c08

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Input In Java- How does it work?

- by Nir Avnon

Hey guys, with a lot of help from you i was managed to write this nice code (I'm new in it, so kind of exciting.. :) ) And still I have not understand how can I input this code. first of all, I get an this error in the console line (I'm using Eclipse): Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at NumberConverter.main(NumberConverter.java:5). What does that mean? I just want to chack whether it works, and I can't call the function/program any how. I used to call in an "old fashion way", like in scheme, to the function that I wrote and see if something happens. How does it work in java? Do we call the program itself? function? what and where do we write? -I want to chack if it works, doesn't matter how, and I'll be glad to know how can I plugin input. Thank you so much! public class NumberConverter{ public static void main(String[] args) { int i = Integer.parseInt(args[0]); toBinary(i); toOctal(i); toHex(i); } public static void toBinary(int int1){ System.out.println(int1 + " in binary is"); System.out.println(Integer.toBinaryString(int1)); } public static void toOctal(int int1){ System.out.println(int1 + " in octal is"); System.out.println(Integer.toOctalString(int1)); } public static void toHex(int int1){ System.out.println(int1 + " in hex is"); System.out.println(Integer.toHexString(int1)); } }

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Threads syncronization with ThreadPoolExecutor

- by justme1

I'm trying to implement some logic when I create main(father) thread witch executes several other threads. Then it waits for some condition which child threads creates. After condition is meet the father executes some more child threads. The problem that when I use wait/notify I have java.lang.IllegalMonitorStateException exception. Here is the code: public class MyExecutor { final static ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(10); final static ExecutorService svc = Executors.newFixedThreadPool(1); static final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5, 8, 10, TimeUnit.SECONDS, queue); public static void main(String[] args) throws InterruptedException { final MyExecutor me = new MyExecutor(); svc.execute(new Runnable() { public void run() { try { System.out.println("Main Thread"); me.execute(threadPool, 1); System.out.println("Main Thread waiting"); wait(); System.out.println("Main Thread notified"); me.execute(threadPool, 2); Thread.sleep(100); threadPool.shutdown(); threadPool.awaitTermination(20000, TimeUnit.SECONDS); } catch (InterruptedException e) { e.printStackTrace(); } } }); svc.shutdown(); svc.awaitTermination(10000, TimeUnit.SECONDS); System.out.println("Main Thread finished"); } public void execute(ThreadPoolExecutor tpe, final int id) { tpe.execute(new Runnable() { public void run() { try { System.out.println("Child Thread " + id); Thread.sleep(2000); System.out.println("Child Thread " + id + " finished"); notify(); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } When I comment wait and notify line I have the following output: Main Thread Main Thread waiting Main Thread notified Child Thread 1 Child Thread 2 Child Thread 1 finished Child Thread 2 finished Main Thread finished

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Java Socket Closes After Connection?

- by Matthew

Why does this port/socket close once a connection has been made by a client? package app; import java.io.*; import java.net.*; public class socketServer { public static void main(String[] args) { int port = 3333; boolean socketBindedToPort = false; try { ServerSocket ServerSocketPort = new ServerSocket(port); System.out.println("SocketServer Set Up on Port: " + port); socketBindedToPort = true; if(socketBindedToPort == true) { Socket clientSocket = null; try { clientSocket = ServerSocketPort.accept();//This method blocks until a socket connection has been made to this port. System.out.println("Waiting for client connection on port:" + port); /** THE CLIENT HAS MADE A CONNECTION **/ System.out.println("CLIENT IS CONENCTED"); } catch (IOException e) { System.out.println("Accept failed: " + port); System.exit(-1); } } else { System.out.println("Socket did not bind to the port:" + port); } } catch(IOException e) { System.out.println("Could not listen on port: " + port); System.exit(-1); } } }

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What output and recording ports does the Java Sound API find on your computer?

- by Dave Carpeneto

Hi all - I'm working with the Java Sound API, and it turns out if I want to adjust recording volumes I need to model the hardware that the OS exposes to Java. Turns out there's a lot of variety in what's presented. Because of this I'm humbly asking that anyone able to help me run the following on their computer and post back the results so that I can get an idea of what's out there. A thanks in advance to anyone that can assist :-) import javax.sound.sampled.*; public class SoundAudit { public static void main(String[] args) { try { System.out.println("OS: "+System.getProperty("os.name")+" "+ System.getProperty("os.version")+"/"+ System.getProperty("os.arch")+"\nJava: "+ System.getProperty("java.version")+" ("+ System.getProperty("java.vendor")+")\n"); for (Mixer.Info thisMixerInfo : AudioSystem.getMixerInfo()) { System.out.println("Mixer: "+thisMixerInfo.getDescription()+ " ["+thisMixerInfo.getName()+"]"); Mixer thisMixer = AudioSystem.getMixer(thisMixerInfo); for (Line.Info thisLineInfo:thisMixer.getSourceLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Source Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}} for (Line.Info thisLineInfo:thisMixer.getTargetLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Target Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}}} } catch (Exception e) {e.printStackTrace();}} public static String AnalyzeControl(Control thisControl) { String type = thisControl.getType().toString(); if (thisControl instanceof BooleanControl) { return " Control: "+type+" (boolean)"; } if (thisControl instanceof CompoundControl) { System.out.println(" Control: "+type+ " (compound - values below)"); String toReturn = ""; for (Control children: ((CompoundControl)thisControl).getMemberControls()) { toReturn+=" "+AnalyzeControl(children)+"\n";} return toReturn.substring(0, toReturn.length()-1);} if (thisControl instanceof EnumControl) { return " Control:"+type+" (enum: "+thisControl.toString()+")";} if (thisControl instanceof FloatControl) { return " Control: "+type+" (float: from "+ ((FloatControl) thisControl).getMinimum()+" to "+ ((FloatControl) thisControl).getMaximum()+")";} return " Control: unknown type";} } All the application does is print out a line about the OS, a line about the JVM, and a few lines about the hardware found that may pertain to recording hardware. For example on my PC at work I get the following: OS: Windows XP 5.1/x86 Java: 1.6.0_07 (Sun Microsystems Inc.) Mixer: Direct Audio Device: DirectSound Playback [Primary Sound Driver] Mixer: Direct Audio Device: DirectSound Playback [SoundMAX HD Audio] Mixer: Direct Audio Device: DirectSound Capture [Primary Sound Capture Driver] Mixer: Direct Audio Device: DirectSound Capture [SoundMAX HD Audio] Mixer: Software mixer and synthesizer [Java Sound Audio Engine] Mixer: Port Mixer [Port SoundMAX HD Audio] Source Port: MICROPHONE source port Control: Microphone (compound - values below) Control: Select (boolean) Control: Microphone Boost (boolean) Control: Front panel microphone (boolean) Control: Volume (float: from 0.0 to 1.0) Source Port: LINE_IN source port Control: Line In (compound - values below) Control: Select (boolean) Control: Volume (float: from 0.0 to 1.0) Control: Balance (float: from -1.0 to 1.0)

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Apache HttpClient Digest authentication

- by Milan Jovic

Hi, Basically what I need to do is to perform digest authentication. First thing I tried is the official example available here. But when I try to execute it(with some small changes, Post instead of the the Get method) I get a org.apache.http.auth.MalformedChallengeException: missing nonce in challange at org.apache.http.impl.auth.DigestScheme.processChallenge(DigestScheme.java:132) When this failed I tried using: DefaultHttpClient client = new DefaultHttpClient(); client.getCredentialsProvider().setCredentials(new AuthScope(null, -1, null), new UsernamePasswordCredentials("<username>", "<password>")); HttpPost post = new HttpPost(URI.create("http://<someaddress>")); List<NameValuePair> nvps = new ArrayList<NameValuePair>(); nvps.add(new BasicNameValuePair("domain", "<username>")); post.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8)); DigestScheme digestAuth = new DigestScheme(); digestAuth.overrideParamter("algorithm", "MD5"); digestAuth.overrideParamter("realm", "http://<someaddress>"); digestAuth.overrideParamter("nonce", Long.toString(new Random().nextLong(), 36)); digestAuth.overrideParamter("qop", "auth"); digestAuth.overrideParamter("nc", "0"); digestAuth.overrideParamter("cnonce", DigestScheme.createCnonce()); Header auth = digestAuth.authenticate(new UsernamePasswordCredentials("<username>", "<password>"), post); System.out.println(auth.getName()); System.out.println(auth.getValue()); post.setHeader(auth); HttpResponse ret = client.execute(post); ByteArrayOutputStream v2 = new ByteArrayOutputStream(); ret.getEntity().writeTo(v2); System.out.println("----------------------------------------"); System.out.println(v2.toString()); System.out.println("----------------------------------------"); System.out.println(ret.getStatusLine().getReasonPhrase()); System.out.println(ret.getStatusLine().getStatusCode()); At first I have only overridden "realm" and "nonce" DigestScheme parameters. But it turned out that PHP script running on the server requires all other params, but no matter if I specify them or not DigestScheme doesn't generate them when I call its authenticate() method. I've been struggling with this for two days, and no luck. Based on everything I think that the cause of the problem is the PHP script. It looks to me that it doesn't send a challenge when app tries to access it unauthorized. Any ideas anyone?

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Java Threading Concept Understanding

- by Nirmal

Hello All... Recently I have gone through with one simple threading program, which leads me some issues for the related concepts... My sample program code looks like : class NewThread implements Runnable { Thread t; NewThread() { t = new Thread(this, "Demo Thread"); System.out.println("Child thread: " + t); t.start(); // Start the thread } public void run() { try { for (int i = 5; i > 0; i--) { System.out.println("Child Thread: " + i); Thread.sleep(500); } } catch (InterruptedException e) { System.out.println("Child interrupted."); } System.out.println("Exiting child thread."); } } class ThreadDemo { public static void main(String args[]) { new NewThread(); // create a new thread try { for (int i = 5; i > 0; i--) { System.out.println("Main Thread: " + i); Thread.sleep(1000); } } catch (InterruptedException e) { System.out.println("Main thread interrupted."); } System.out.println("Main thread exiting."); } } Now this program giving me the output as follows : Child thread: Thread[Demo Thread,5,main] Main Thread: 5 Child Thread: 5 Child Thread: 4 Main Thread: 4 Child Thread: 3 Child Thread: 2 Main Thread: 3 Child Thread: 1 Exiting child thread. Main Thread: 2 Main Thread: 1 Main thread exiting. So, that's very much clear to me. But as soon as I am replacing the object creation code (calling of a NewThread class constructor) to as follows : NewThread nt = new NewThread(); // create a new thread the output becomes a bit varied like as follows : Child thread: Thread[Demo Thread,5,main] Main Thread: 5 Child Thread: 5 Child Thread: 4 Child Thread: 3 Main Thread: 4 Child Thread: 2 Child Thread: 1 Main Thread: 3 Exiting child thread. Main Thread: 2 Main Thread: 1 Main thread exiting. And some times it's giving me same output in both the cases. So, i am not getting the exact change in both the scenario. I would like to know that you the variation in the output is coming here ? Thanks in advance...

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List input and output audio devices in Applet

- by Jhonny Everson

I am running a signed applet that needs to provide the ability for the user to select the input and output audio devices ( similar to what skype provides). I borrowed the following code from other thread: import javax.sound.sampled.*; public class SoundAudit { public static void main(String[] args) { try { System.out.println("OS: "+System.getProperty("os.name")+" "+ System.getProperty("os.version")+"/"+ System.getProperty("os.arch")+"\nJava: "+ System.getProperty("java.version")+" ("+ System.getProperty("java.vendor")+")\n"); for (Mixer.Info thisMixerInfo : AudioSystem.getMixerInfo()) { System.out.println("Mixer: "+thisMixerInfo.getDescription()+ " ["+thisMixerInfo.getName()+"]"); Mixer thisMixer = AudioSystem.getMixer(thisMixerInfo); for (Line.Info thisLineInfo:thisMixer.getSourceLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Source Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}} for (Line.Info thisLineInfo:thisMixer.getTargetLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Target Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}}} } catch (Exception e) {e.printStackTrace();}} public static String AnalyzeControl(Control thisControl) { String type = thisControl.getType().toString(); if (thisControl instanceof BooleanControl) { return " Control: "+type+" (boolean)"; } if (thisControl instanceof CompoundControl) { System.out.println(" Control: "+type+ " (compound - values below)"); String toReturn = ""; for (Control children: ((CompoundControl)thisControl).getMemberControls()) { toReturn+=" "+AnalyzeControl(children)+"\n";} return toReturn.substring(0, toReturn.length()-1);} if (thisControl instanceof EnumControl) { return " Control:"+type+" (enum: "+thisControl.toString()+")";} if (thisControl instanceof FloatControl) { return " Control: "+type+" (float: from "+ ((FloatControl) thisControl).getMinimum()+" to "+ ((FloatControl) thisControl).getMaximum()+")";} return " Control: unknown type";} } But what I get: Mixer: Software mixer and synthesizer [Java Sound Audio Engine] Mixer: No details available [Microphone (Pink Front)] I was expecting the get the real list of my devices (My preferences panels shows 3 output devices and 1 Microphone). I am running on Mac OS X 10.6.7. Is there other way to get that info from Java?

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Java - Highest, Lowest and Average

- by Emily

Hello, I've just started studying and I need help on one of my exercises. I need the end user to input a rain fall number for each month. I then need to out put the average rainfall, highest month and lowest month and the months which rainfall was above average. I keep getting the same number in the highest and lowest and I have no idea why. I am seriously pulling my hair out. Any help would be greatly appreciated. This is what I have so far: public class rainfall { /** * @param args */ public static void main(String[] args) { int[] numgroup; numgroup = new int [13]; ConsoleReader console = new ConsoleReader(); int highest; int lowest; int index; int tempVal; int minMonth; int minIndex; int maxMonth; int maxIndex; System.out.println("Welcome to Rainfall"); for(index = 1; index < 13; index = index + 1) { System.out.println("Please enter the rainfall for month " + index); tempVal = console.readInt(); while (tempVal>100 || tempVal<0) { System.out.println("The rating must be within 0...100. Try again"); tempVal = console.readInt(); } numgroup[index] = tempVal; } lowest = numgroup[0]; for(minIndex = 0; minIndex < numgroup.length; minIndex = minIndex + 1); { if (numgroup[0] < lowest) { lowest = numgroup[0]; minMonth = minIndex; } } highest = numgroup[1]; for(maxIndex = 0; maxIndex < numgroup.length; maxIndex = maxIndex + 1); { if (numgroup[1] > highest) { highest = numgroup[1]; maxMonth = maxIndex; } } System.out.println("The average monthly rainfall was "); System.out.println("The lowest monthly rainfall was month " + minIndex); System.out.println("The highest monthly rainfall was month " + maxIndex); System.out.println("Thank you for using Rainfall"); } private static ConsoleReader ConsoleReader() { return null; } } Thanks, Emily

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Java - Highest, Lowest and Average

- by Emily

Right, so why does Java come up with this error: Exception in thread "main" java.lang.Error: Unresolved compilation problem: Type mismatch: cannot convert from double to int at rainfall.main(rainfall.java:38) From this: public class rainfall { /** * @param args */ public static void main(String[] args) { int[] numgroup; numgroup = new int [12]; ConsoleReader console = new ConsoleReader(); int highest; int lowest; int index; int tempVal; int minMonth; int minIndex; int maxMonth; int maxIndex; System.out.println("Welcome to Rainfall"); // Input (index now 0-based) for(index = 0; index < 12; index = index + 1) { System.out.println("Please enter the rainfall for month " + index + 1); tempVal = console.readInt(); while (tempVal100 || tempVal<0) { System.out.println("The rating must be within 0...100. Try again"); tempVal = console.readInt(); } numgroup[index] = tempVal; } lowest = numgroup[0]; highest = numgroup[0]; int total = 0.0; // Loop over data (using 1 loop) for(index = 0; index < 12; index = index + 1) { int curr = numgroup[index]; if (curr < lowest) { lowest = curr; minIndex = index; } if (curr highest) { highest = curr; maxIndex = index; } total += curr; } float avg = (float)total / numgroup.length; System.out.println("The average monthly rainfall was " + avg); // +1 to go from 0-based index to 1-based month System.out.println("The lowest monthly rainfall was month " + minIndex + 1); System.out.println("The highest monthly rainfall was month " + maxIndex + 1); System.out.println("Thank you for using Rainfall"); } private static ConsoleReader ConsoleReader() { return null; } }

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jcuda library usage problem

- by user513164

hi m very new to java and Linux i have a code which is taken from examples of jcuda.the code is following import jcuda.CUDA; import jcuda.driver.CUdevprop; import jcuda.driver.types.CUdevice; public class EnumDevices { public static void main(String args[]) { //Init CUDA Driver CUDA cuda = new CUDA(true); int count = cuda.getDeviceCount(); System.out.println("Total number of devices: " + count); for (int i = 0; i < count; i++) { CUdevice dev = cuda.getDevice(i); String name = cuda.getDeviceName(dev); System.out.println("Name: " + name); int version[] = cuda.getDeviceComputeCapability(dev); System.out.println("Version: " + String.format("%d.%d", version[0], version[1])); CUdevprop prop = cuda.getDeviceProperties(dev); System.out.println("Clock rate: " + prop.clockRate + " MHz"); System.out.println("Threads per block: " + prop.maxThreadsPerBlock); } } } I'm using Ubuntu as my operating system i compiled it with following command 1:-javac -cp /home/manish.yadav/Desktop/JCuda-All-0.3.2-bin-linux-x86_64 EnumDevices i got following error error: Class names, 'EnumDevices', are only accepted if annotation processing is explicitly requested 1 error i don't know what is the meaning of this error.what should i do to compile the program than i changed the compiling option which is javac -cp /home/manish.yadav/Desktop/JCuda-All-0.3.2-bin-linux-x86_64 EnumDevices.java than i got following error EnumDevices.java:36: clockRate is not public in jcuda.driver.CUdevprop; cannot be accessed from outside package System.out.println("Clock rate: " + prop.clockRate + " MHz"); ^ EnumDevices.java:37: maxThreadsPerBlock is not public in jcuda.driver.CUdevprop; cannot be accessed from outside package System.out.println("Threads per block: " + prop.maxThreadsPerBlock); ^ 2 errors Now I'm completely confused i don't know what to do? how to compile this program ? how to install the jcuda package or how to use it ? how to use package which have only jar files and .so files and the jar files don't having manifest file ? please help me

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Java - Is Set.contains() broken on OpenJDK 6?

- by Peter

Hey, I've come across a really strange problem. I have written a simple Deck class which represents a standard 52 card deck of playing cards. The class has a method missingCards() which returns the set of all cards which have been drawn from the deck. If I try and compare two identical sets of missing cards using .equals() I'm told they are different, and if I check to see if a set contains an element that I know is there using .contains() I am returned false. Here is my test code: public void testMissingCards() { Deck deck = new Deck(true); Set<Card> drawnCards = new HashSet<Card>(); drawnCards.add(deck.draw()); drawnCards.add(deck.draw()); drawnCards.add(deck.draw()); Set<Card> missingCards = deck.missingCards(); System.out.println(drawnCards); System.out.println(missingCards); Card c1 = null; for (Card c : drawnCards){ c1 = c; } System.out.println("C1 is "+c1); for (Card c : missingCards){ System.out.println("C is "+c); System.out.println("Does c1.equal(c) "+c1.equals(c)); System.out.println("Does c.equal(c1) "+c.equals(c1)); } System.out.println("Is c1 in missingCards "+missingCards.contains(c1)); assertEquals("Deck confirm missing cards",drawnCards,missingCards); } (Edit: Just for clarity I added the two loops after I noticed the test failing. The first loop pulls out a card from drawnCards and then this card is checked against every card in missingCards - it always matches one, so that card must be contained in missingCards. However, missingCards.contains() fails) And here is an example of it's output: [5C, 2C, 2H] [2C, 5C, 2H] C1 is 2H C is 2C Does c1.equal(c) false Does c.equal(c1) false C is 5C Does c1.equal(c) false Does c.equal(c1) false C is 2H Does c1.equal(c) true Does c.equal(c1) true Is c1 in missingCards false I am completely sure that the implementation of .equals on my card class is correct and, as you can see from the output it does work! What is going on here? Cheers, Pete

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Why is javac 1.5 running so slowly compared with the Eclipse compiler?

- by Simon Nickerson

I have a Java Maven project with about 800 source files (some generated by javacc/JTB) which is taking a good 25 minutes to compile with javac. When I changed my pom.xml over to use the Eclipse compiler, it takes about 30 seconds to compile. Any suggestions as to why javac (1.5) is running so slowly? (I don't want to switch over to the Eclipse compiler permanently, as the plugin for Maven seems more than a little buggy.) I have a test case which easily reproduces the problem. The following code generates a number of source files in the default package. If you try to compile ImplementingClass.java with javac, it will seem to pause for an inordinately long time. import java.io.File; import java.io.FileNotFoundException; import java.io.PrintStream; public class CodeGenerator { private final static String PATH = System.getProperty("java.io.tmpdir"); private final static int NUM_TYPES = 1000; public static void main(String[] args) throws FileNotFoundException { PrintStream interfacePs = new PrintStream(PATH + File.separator + "Interface.java"); PrintStream abstractClassPs = new PrintStream(PATH + File.separator + "AbstractClass.java"); PrintStream implementingClassPs = new PrintStream(PATH + File.separator + "ImplementingClass.java"); interfacePs.println("public interface Interface<T> {"); abstractClassPs.println("public abstract class AbstractClass<T> implements Interface<T> {"); implementingClassPs.println("public class ImplementingClass extends AbstractClass<Object> {"); for (int i=0; i<NUM_TYPES; i++) { String nodeName = "Node" + i; PrintStream nodePs = new PrintStream(PATH + File.separator + nodeName + ".java"); nodePs.printf("public class %s { }\n", nodeName); nodePs.close(); interfacePs.printf("void visit(%s node, T obj);%n", nodeName); abstractClassPs.printf("public void visit(%s node, T obj) { System.out.println(obj.toString()); }%n", nodeName); } interfacePs.println("}"); abstractClassPs.println("}"); implementingClassPs.println("}"); interfacePs.close(); abstractClassPs.close(); implementingClassPs.close(); } }

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Blackberry ListField Text Wrapping - only two lines.

- by Diego Tori

Within my ListField, I want to be able to take any given long String, and just be able to wrap the first line within the width of the screen, and just take the remaining string and display it below and ellipsis the rest. Right now, this is what I'm using to detect wrapping within my draw paint call: int totalWidth = 0; int charWidth = 0; int lastIndex = 0; int spaceIndex = 0; int lineIndex = 0; String firstLine = ""; String secondLine = ""; boolean isSecondLine = false; for (int i = 0; i < longString.length(); i++){ charWidth = Font.getDefault().getAdvance(String.valueOf(longString.charAt(i))); //System.out.println("char width: " + charWidth); if(longString.charAt(i) == ' ') spaceIndex = i; if((charWidth + totalWidth) > (this.getWidth()-32)){ //g.drawText(longString.substring(lastIndex, spaceIndex), xpos, y +_padding, DrawStyle.LEFT, w - xpos); lineIndex++; System.out.println("current lines to draw: " + lineIndex); /*if (lineIndex = 2){ int idx = i; System.out.println("first line " + longString.substring(lastIndex, spaceIndex)); System.out.println("second line " + longString.substring(spaceIndex+1, longString.length())); }*/ //firstLine = longString.substring(lastIndex, spaceIndex); firstLine = longString.substring(0, spaceIndex); //System.out.println("first new line: " +firstLine); //isSecondLine=true; //xpos = 0; //y += Font.getDefault().getHeight(); i = spaceIndex + 1; lastIndex = i; System.out.println("Rest of string: " + longString.substring(lastIndex, longString.length())); charWidth = 0; totalWidth = 0; } totalWidth += charWidth; System.out.println("total width: " + totalWidth); //g.drawText(longString.substring(lastIndex, i+1), xpos, y + (_padding*3)+4, DrawStyle.ELLIPSIS, w - xpos); //secondLine = longString.substring(lastIndex, i+1); secondLine = longString.substring(lastIndex, longString.length()); //isSecondLine = true; } Now this does a great job of actually wrapping any given string (assuming the y values were properly offsetted and it only drew the text after the string width exceeded the screen width, as well as the remaining string afterwards), however, every time I try to get the first two lines, it always ends up returning the last two lines of the string if it goes beyond two lines. Is there a better way to do this sort of thing, since I am fresh out of ideas?

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Why an object declared in method is subject to garbage collection before the method returns?

- by SiLent SoNG

Consider an object declared in a method: public void foo() { final Object obj = new Object(); // A long run job that consumes tons of memory and // triggers garbage collection } Will obj be subject to garbage collection before foo() returns? UPDATE: Previously I thought obj is not subject to garbage collection until foo() returns. However, today I find myself wrong. I have spend several hours in fixing a bug and finally found the problem is caused by obj garbage collected! Can anyone explain why this happens? And if I want obj to be pinned how to achieve it? Here is the code that has problem. public class Program { public static void main(String[] args) throws Exception { String connectionString = "jdbc:mysql://<whatever>"; // I find wrap is gc-ed somewhere SqlConnection wrap = new SqlConnection(connectionString); Connection con = wrap.currentConnection(); Statement stmt = con.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY); stmt.setFetchSize(Integer.MIN_VALUE); ResultSet rs = stmt.executeQuery("select instance_id, doc_id from crawler_archive.documents"); while (rs.next()) { int instanceID = rs.getInt(1); int docID = rs.getInt(2); if (docID % 1000 == 0) { System.out.println(docID); } } rs.close(); //wrap.close(); } } After running the Java program, it will print the following message before it crashes: 161000 161000 ******************************** Finalizer CALLED!! ******************************** ******************************** Close CALLED!! ******************************** 162000 Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: And here is the code of class SqlConnection: class SqlConnection { private final String connectionString; private Connection connection; public SqlConnection(String connectionString) { this.connectionString = connectionString; } public synchronized Connection currentConnection() throws SQLException { if (this.connection == null || this.connection.isClosed()) { this.closeConnection(); this.connection = DriverManager.getConnection(connectionString); } return this.connection; } protected void finalize() throws Throwable { try { System.out.println("********************************"); System.out.println("Finalizer CALLED!!"); System.out.println("********************************"); this.close(); } finally { super.finalize(); } } public void close() { System.out.println("********************************"); System.out.println("Close CALLED!!"); System.out.println("********************************"); this.closeConnection(); } protected void closeConnection() { if (this.connection != null) { try { connection.close(); } catch (Throwable e) { } finally { this.connection = null; } } } }

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What am I encrypting wrong here?

- by Katie Krueger

So I have a wordplay project to do and I have to encrypt some characters. I am at the point where I am stuck, and when I run it and type 1 for encrypt it doesn't shift that many letters. It just prints the work over again. I am wondering what I could do to fix it where if I say "hello" it will print 1 character over and say "ifmmp" Thank you! import java.util.Scanner; public class WordPlayTester{ public static void main(String [] args){ String word, reverse=""; String original; int key= 0; String Menu= "1-Encrypt \n2-Decrypt \n3-Is Palindrome \n0-Quit \n-Select an option-"; Scanner in = new Scanner(System.in); System.out.println("-Type any word-"); word = in.nextLine(); System.out.println(Menu); int choice=in.nextInt(); if(choice==1) { System.out.println("Insert a Key number"); int select= in.nextInt(); for (int i=0; i < word.length(); i++) { char c = word.charAt(i); if (c >= 'A' && c <= 'Z') { c = (char)(c - 64); int n = c+1; n = n % 26; if (n < 0) { n = n + 26; } c = (char)(n + 65); } System.out.println(c); } } else if(choice==3) { int length = word.length(); for ( int i = length - 1 ; i >= 0 ; i-- ) reverse = reverse + word.charAt(i); if (word.equals(reverse)) System.out.println("Your word is a palindrome."); else System.out.println("Your word is not a palindrome."); } else if(choice==0) { System.exit(0); } else { System.out.println(Menu); } } }

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