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  • How to set more panels in Java

    - by baklap
    I need to get two JPanels into one JApplet. paneel = new RekenmachinePaneel(); nummer = new NummerPaneel(); setContentPane(paneel); Now I need to get the nummer panel to show up beneath the paneel. How should I do that?

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  • Java anonymous class efficiency implications

    - by Po
    Is there any difference in efficiency (e.g. execution time, code size, etc.) between these two ways of doing things? Below are contrived examples that create objects and do nothing, but my actual scenarios may be creating new Threads, Listeners, etc. Assume the following pieces of code happen in a loop so that it might make a difference. Using anonymous objects: void doSomething() { for (/* Assume some loop */) { final Object obj1, obj2; // some free variables IWorker anonymousWorker = new IWorker() { doWork() { // do things that refer to obj1 and obj2 } }; } } Defining a class first: void doSomething() { for (/* Assume some loop */) { Object obj1, obj2; IWorker worker = new Worker(obj1, obj2); } } static class Worker implements IWorker { private Object obj1, obj2; public CustomObject(Object obj1, Object obj2) {/* blah blah */} @Override public void doWork() {} }; Thank you :)

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  • Upload files with java

    - by Marius
    I'd like to upload a few files to a http server. Basically what i need is some sort of a post request to the server with a few parameters and the files. I've seen examples of just uploading files, but didn't find how to also pass additional parameters. So the question would be what's the simplest and free solution of doing this? Does anyone have any file upload examples that i could study? I've been googling for a few hours, but (maybe it's just one of those days) couldn't find exactly what i needed. The best solution would be something that doesn't involve any third party classes or libraries. Thank you

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  • Java threadpool functionality

    - by cpf
    Hi stackoverflow, I need to make a program with a limited amount of threads (currently using newFixedThreadPool) but I have the problem that all threads get created from start, filling up memory at alarming rate. I wish to prevent this. Threads should only be created shortly before they are executed. e.g.: I call the program and instruct it to use 2 threads in the pool. The program should create & launch the first 2 Threads immediately (obviously), create the next 2 to wait for the previous 2, and at that point wait until one or both of the first 2 ended executing. I thought about extending executor or FixedThreadPool or such. However I have no clue on how to start there and doubt it is the best solution. Easiest would have my main Thread sleeping on intervals, which is not really good either... Thanks in advance!

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  • Java BufferedWriter close()

    - by rakeshr
    Hi, assume that I have the following code fragment operation1(); bw.close(); operation2(); When I call BufferedReader.close() from my code, I am assuming my JVM makes a system call that ensures that the buffer has been flushed and written to disk. I want to know if close() waits for the system call to complete its operation or does it proceed to operation2() without waiting for close() to finish. To rephrase my question, when I do operation2(), can I assume that bw.close() has completed successfully?

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  • org.apache.http.conn.HttpHostConnectException:Connection to http://172.20.38.143 refused

    - by Passion
    I have developed client server Application .I am accessing mysql with php running on my machine and client running on my cell which is connected to machine.WI-FI is also switched ON. Internet Permission are also added in Manifest file but then also the i encounter error 172.20.38.143 is IP OF MY MACHINE 06-01 13:20:10.391: W/System.err(11157): org.apache.http.conn.HttpHostConnectException: Connection to http://172.20.38.143 refused 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:183) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:674) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:511) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:489) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.library.JSONParser.getJSONFromUrl(JSONParser.java:42) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.library.UserFunctions.registerUser(UserFunctions.java:59) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.RegisterActivity$1.onClick(RegisterActivity.java:52) 06-01 13:20:10.411: W/System.err(11157): at android.view.View.performClick(View.java:3567) 06-01 13:20:10.411: W/System.err(11157): at android.view.View$PerformClick.run(View.java:14224) 06-01 13:20:10.411: W/System.err(11157): at android.os.Handler.handleCallback(Handler.java:605) 06-01 13:20:10.411: W/System.err(11157): at android.os.Handler.dispatchMessage(Handler.java:92) 06-01 13:20:10.411: W/System.err(11157): at android.os.Looper.loop(Looper.java:137) 06-01 13:20:10.411: W/System.err(11157): at android.app.ActivityThread.main(ActivityThread.java:4517) 06-01 13:20:10.411: W/System.err(11157): at java.lang.reflect.Method.invokeNative(Native Method) 06-01 13:20:10.411: W/System.err(11157): at java.lang.reflect.Method.invoke(Method.java:511) 06-01 13:20:10.411: W/System.err(11157): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993) 06-01 13:20:10.421: W/System.err(11157): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760) 06-01 13:20:10.421: W/System.err(11157): at dalvik.system.NativeStart.main(Native Method) 06-01 13:20:10.421: W/System.err(11157): Caused by: java.net.ConnectException: failed to connect to /172.20.38.143 (port 80): connect failed: ENETUNREACH (Network is unreachable) 06-01 13:20:10.431: W/System.err(11157): at libcore.io.IoBridge.connect(IoBridge.java:114) 06-01 13:20:10.431: W/System.err(11157): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 06-01 13:20:10.431: W/System.err(11157): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 06-01 13:20:10.431: W/System.err(11157): at java.net.Socket.connect(Socket.java:848) 06-01 13:20:10.431: W/System.err(11157): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 06-01 13:20:10.431: W/System.err(11157): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 06-01 13:20:10.431: W/System.err(11157): ... 20 more 06-01 13:20:10.431: W/System.err(11157): Caused by: libcore.io.ErrnoException: connect failed: ENETUNREACH (Network is unreachable) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.Posix.connect(Native Method) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.IoBridge.connect(IoBridge.java:112) 06-01 13:20:10.441: W/System.err(11157): ... 25 more 06-01 13:20:10.441: E/Buffer Error(11157): Error converting result java.lang.NullPointerException 06-01 13:20:10.451: E/JSON Parser(11157): Error parsing data org.json.JSONException: End of input at character 0 of 06-01 13:20:10.451: D/AndroidRuntime(11157): Shutting down VM 06-01 13:20:10.451: W/dalvikvm(11157): threadid=1: thread exiting with uncaught exception (group=0x40c0aa68) 06-01 13:20:10.451: E/AndroidRuntime(11157): FATAL EXCEPTION: main 06-01 13:20:10.451: E/AndroidRuntime(11157): java.lang.NullPointerException 06-01 13:20:10.451: E/AndroidRuntime(11157): at nineandroid.net.example.RegisterActivity$1.onClick(RegisterActivity.java:56) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.view.View.performClick(View.java:3567) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.view.View$PerformClick.run(View.java:14224) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Handler.handleCallback(Handler.java:605) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Handler.dispatchMessage(Handler.java:92) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Looper.loop(Looper.java:137) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.app.ActivityThread.main(ActivityThread.java:4517) 06-01 13:20:10.451: E/AndroidRuntime(11157): at java.lang.reflect.Method.invokeNative(Native Method) 06-01 13:20:10.451: E/AndroidRuntime(11157): at java.lang.reflect.Method.invoke(Method.java:511) 06-01 13:20:10.451: E/AndroidRuntime(11157): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993) 06-01 13:20:10.451: E/AndroidRuntime(11157): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760) 06-01 13:20:10.451: E/AndroidRuntime(11157): at dalvik.system.NativeStart.main(Native Method) UserFunctions.java to call jsonParser public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "http://172.20.38.143/ah_login_api/"; private static String registerURL = "http://172.20.38.143/ah_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl(loginURL, params); // return json // Log.e("JSON", json.toString()); return json; } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl(registerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } } jsonParser.java public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); Log.e("JSON", json); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } RegisterActivity.java public class RegisterActivity extends Activity { Button btnRegister; Button btnLinkToLogin; EditText inputFullName; EditText inputEmail; EditText inputPassword; TextView registerErrorMsg; // JSON Response node names private static String KEY_SUCCESS = "success"; private static String KEY_UID = "uid"; private static String KEY_NAME = "name"; private static String KEY_EMAIL = "email"; private static String KEY_CREATED_AT = "created_at"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.register); // Importing all assets like buttons, text fields inputFullName = (EditText) findViewById(R.id.registerName); inputEmail = (EditText) findViewById(R.id.registerEmail); inputPassword = (EditText) findViewById(R.id.registerPassword); btnRegister = (Button) findViewById(R.id.btnRegister); btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen); registerErrorMsg = (TextView) findViewById(R.id.register_error); // Register Button Click event btnRegister.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { String name = inputFullName.getText().toString(); String email = inputEmail.getText().toString(); String password = inputPassword.getText().toString(); UserFunctions userFunction = new UserFunctions(); JSONObject json = userFunction.registerUser(name, email, password); // check for login response try { if (json.getString(KEY_SUCCESS) != null) { registerErrorMsg.setText(""); String res = json.getString(KEY_SUCCESS); if(Integer.parseInt(res) == 1){ // user successfully registred // Store user details in SQLite Database DatabaseHandler db = new DatabaseHandler(getApplicationContext()); JSONObject json_user = json.getJSONObject("user"); // Clear all previous data in database userFunction.logoutUser(getApplicationContext()); db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT)); // Launch Dashboard Screen Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class); // Close all views before launching Dashboard dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(dashboard); // Close Registration Screen finish(); }else{ // Error in registration registerErrorMsg.setText("Error occured in registration"); } } } catch (JSONException e) { e.printStackTrace(); } } }); // Link to Login Screen btnLinkToLogin.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { Intent i = new Intent(getApplicationContext(), LoginActivity.class); startActivity(i); // Close Registration View finish(); } }); } }

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  • parallel computation for an Iterator of elements in Java

    - by Brian Harris
    I've had the same need a few times now and wanted to get other thoughts on the right way to structure a solution. The need is to perform some operation on many elements on many threads without needing to have all elements in memory at once, just the ones under computation. As in, Iterables.partition is insufficient because it brings all elements into memory up front. Expressing it in code, I want to write a BulkCalc2 that does the same thing as BulkCalc1, just in parallel. Below is sample code that illustrates my best attempt. I'm not satisfied because it's big and ugly, but it does seem to accomplish my goals of keeping threads highly utilized until the work is done, propagating any exceptions during computation, and not having more than numThreads instances of BigThing necessarily in memory at once. I'll accept the answer which meets the stated goals in the most concise way, whether it's a way to improve my BulkCalc2 or a completely different solution. interface BigThing { int getId(); String getString(); } class Calc { // somewhat expensive computation double calc(BigThing bigThing) { Random r = new Random(bigThing.getString().hashCode()); double d = 0; for (int i = 0; i < 100000; i++) { d += r.nextDouble(); } return d; } } class BulkCalc1 { final Calc calc; public BulkCalc1(Calc calc) { this.calc = calc; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { TreeMap<Integer, Double> results = Maps.newTreeMap(); while (in.hasNext()) { BigThing o = in.next(); results.put(o.getId(), calc.calc(o)); } return results; } } class SafeIterator<T> { final Iterator<T> in; SafeIterator(Iterator<T> in) { this.in = in; } synchronized T nextOrNull() { if (in.hasNext()) { return in.next(); } return null; } } class BulkCalc2 { final Calc calc; final int numThreads; public BulkCalc2(Calc calc, int numThreads) { this.calc = calc; this.numThreads = numThreads; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { ExecutorService e = Executors.newFixedThreadPool(numThreads); List<Future<?>> futures = Lists.newLinkedList(); final Map<Integer, Double> results = new MapMaker().concurrencyLevel(numThreads).makeMap(); final SafeIterator<BigThing> it = new SafeIterator<BigThing>(in); for (int i = 0; i < numThreads; i++) { futures.add(e.submit(new Runnable() { @Override public void run() { while (true) { BigThing o = it.nextOrNull(); if (o == null) { return; } results.put(o.getId(), calc.calc(o)); } } })); } e.shutdown(); for (Future<?> future : futures) { try { future.get(); } catch (InterruptedException ex) { // swallowing is OK } catch (ExecutionException ex) { throw Throwables.propagate(ex.getCause()); } } return new TreeMap<Integer, Double>(results); } }

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  • Static and overriding in Java

    - by Abhishek Jain
    public class B { static int i =1; public static int multiply(int a,int b) { return i; } public int multiply1(int a,int b) { return i; } public static void main(String args[]) { B b = new A(); System.out.println(b.multiply(5,2)); System.out.println(b.multiply1(5,2)); } } class A extends B { static int i =8; public static int multiply(int a,int b) { return 5*i; } public int multiply1(int a,int b) { return 5*i; } } Output: 1 40 Why is it so? Please explain.

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  • Java variables -> replace? RAM optimization

    - by poeschlorn
    Hi guys, I just wanted to know what happens behind my program when I declare and initialize a variable and later initialize it again with other values, e.g. an ArrayList or something similar. What happens in my RAM, when I say e.g. this: ArrayList<String> al = new ArrayList<String>(); ...add values, work with it and so on.... al = new ArrayList<String>(); So is my first ArrayList held in RAM or will the second ArrayList be stored on the same position where the first one has been before? Or will it just change the reference of "al"? If it is not replaced...is there a way to manually free the RAM which was occupied by the first arraylist? (without waiting for the garbage collector) Would it help to set it first =null? Nice greetings, poeschlorn

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  • Java multi Generic collection parameters complie error

    - by Geln Yang
    Hi, So strange!Please have a look the code first: public class A { } public class B extends A { } public class C extends A { } public class TestMain { public <T extends A> void test(T a, T b) { } public <T extends A> void test(List<T> a, List<T> b) { } public static void main(String[] args) { new TestMain().test(new B(), new C()); new TestMain().test(new ArrayList<B>(), new ArrayList<C>()); } } The statement "new TestMain().test(new ArrayList(), new ArrayList())" get a "Bound mismatch" compile error, while "new TestMain().test(new B(), new C())" is compiled ok. Bound mismatch: The generic method test(T, T) of type TestMain is not applicable for the arguments (ArrayList, ArrayList). The inferred type ArrayList is not a valid substitute for the bounded parameter It seems the type of the second generic List parameter is limited by the Type of the first.Is it a feature or a bug of the compile program? ps, jdk:1.6,IDE:Eclipse 3.5.1

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  • Filling a byte array in Java

    - by Corleone
    Hey all! For part of a project I'm working on I am implementing a RTPpacket where I have to fill the header array of byte with RTP header fields. //size of the RTP header: static int HEADER_SIZE = 12; // bytes //Fields that compose the RTP header public int Version; // 2 bits public int Padding; // 1 bit public int Extension; // 1 bit public int CC; // 4 bits public int Marker; // 1 bit public int PayloadType; // 7 bits public int SequenceNumber; // 16 bits public int TimeStamp; // 32 bits public int Ssrc; // 32 bits //Bitstream of the RTP header public byte[] header = new byte[ HEADER_SIZE ]; This was my approach: /* * bits 0-1: Version * bit 2: Padding * bit 3: Extension * bits 4-7: CC */ header[0] = new Integer( (Version << 6)|(Padding << 5)|(Extension << 6)|CC ).byteValue(); /* * bit 0: Marker * bits 1-7: PayloadType */ header[1] = new Integer( (Marker << 7)|PayloadType ).byteValue(); /* SequenceNumber takes 2 bytes = 16 bits */ header[2] = new Integer( SequenceNumber >> 8 ).byteValue(); header[3] = new Integer( SequenceNumber ).byteValue(); /* TimeStamp takes 4 bytes = 32 bits */ for ( int i = 0; i < 4; i++ ) header[7-i] = new Integer( TimeStamp >> (8*i) ).byteValue(); /* Ssrc takes 4 bytes = 32 bits */ for ( int i = 0; i < 4; i++ ) header[11-i] = new Integer( Ssrc >> (8*i) ).byteValue(); Any other, maybe 'better' ways to do this?

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  • How to give xpath expression in java using axiom

    - by user1811206
    <resource name="cde.xml" status="updated" isCollection="false"> <mediaType>xml</mediaType> <creator>admin</creator> <createdTime>1352783477964</createdTime> <lastUpdater>admin</lastUpdater> <lastModified>1352783477964</lastModified> <description /> <version>0</version> <content>ZGFza2QgbGQgbGt2Zmx3ZGFzamQgYWRsa2ogYWxramRrbGEgamQK </content> </resource> i want to catch nodes which are having status using xpath here is the xpath expression other part of the code is correct. I have problem with xpath expression AXIOMXPath xpathExpression = new AXIOMXPath ( "//resourse[@name]");

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  • Java: Line appears when using AffineTransform to scale image

    - by Malakim
    Hi, I'm having a problem with image scaling. When I use the following code to scale an image it ends up with a line either at the bottom or on the right side of the image. double scale = 1; if (scaleHeight >= scaleWidth) { scale = scaleWidth; } else { scale = scaleHeight; } AffineTransform af = new AffineTransform(); af.scale(scale, scale); AffineTransformOp operation = new AffineTransformOp(af, AffineTransformOp.TYPE_NEAREST_NEIGHBOR); BufferedImage bufferedThumb = operation.filter(img, null); The original image is here: http://tinyurl.com/yzv6r7h The scaled image: http://tinyurl.com/yk6e8ga Does anyone know why the line appears? Thanks!

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  • Caesar Cipher in Java (Spanish Characters)

    - by Rodolfo
    I've reading this question, and I was wondering if Is there any way to consider the whole range of characters? For example, "á", "é", "ö", "ñ", and not consider " " (the [Space])? (For example, my String is "Hello World", and the standard result is "Khoor#Zruog"; I want to erase that "#", so the result would be "KhoorZruog") I'm sure my answer is in this piece of code: if (c >= 32 && c <= 127) { // Change base to make life easier, and use an // int explicitly to avoid worrying... cast later int x = c - 32; x = (x + shift) % 96; chars[i] = (char) (x + 32); } But I've tried some things, and it didn't work.

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  • Java enums in generic type

    - by Marcin Cylke
    Hi, I'd like to create a generic enum-based mapper for IBatis. I'm doing this with the below code. This does have compile time errors, which I don't know how to fix. Maybe my solution is just plain wrong (keep in mind the use of IBatis), in such case please suggest something better. Any help appreciated. What I want to achieve is to define subsequent mappers as: public class XEnumTypeHandler extends CommonEnumTypeHandler<X> { } The current code: public class CommonEnumTypeHandler<T extends Enum> implements TypeHandlerCallback { public void setParameter(ParameterSetter ps, Object o) throws SQLException { if (o.getClass().isAssignableFrom(**T**)) { ps.setString(((**T**) o).value().toUpperCase()); } else throw new SQLException("Excpected ParameterType object than: " + o); } public Object getResult(ResultGetter rs) throws SQLException { Object o = valueOf(rs.getString()); if (o == null) throw new SQLException("Unknown parameter type: " + rs.getString()); return o; } public Object valueOf(String s) { for (T pt : T.**values()**) { if (pt.**value()**.equalsIgnoreCase(s)) return pt; } return null; } } I've added error markings to the above code, the error messages are in order: T cannot be resolved The method value() is undefined for the type T The method values() is undefined for the type T The method values() is undefined for the type T

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  • java dynamic memory allocation?

    - by JavaUser
    Hi, Why an object initialization using " new " keyword is called as dynamic memory allocation since compile time itself we know the memory needed for that object . Also please explain what happen when u do ClassA object = new ClassA(); in heap and stack . Thx

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  • When using Clipboard, Toolkit and Transferable, I get an error objecting to image width and height

    - by Mike King
    When I run the following code it triggers an error message. The error message is shown below the code. What code changes, or changes to the image file, are needed to fix this error? Help will be appreciated. import java.awt.*; import java.awt.datatransfer.*; public class LoadToClipboard { public static void main( String [] args ) { Toolkit tolkit = Toolkit.getDefaultToolkit(); Clipboard clip = tolkit.getSystemClipboard(); clip.setContents( new ImageSelection( tolkit.getImage("StackOverflowLogo.png")) , null ); } } class ImageSelection implements Transferable { private Image image; public ImageSelection(Image image) { this.image = image; } // Returns supported flavors public DataFlavor[] getTransferDataFlavors() { return new DataFlavor[]{DataFlavor.imageFlavor}; } // Returns true if flavor is supported public boolean isDataFlavorSupported(DataFlavor flavor) { return DataFlavor.imageFlavor.equals(flavor); } // Returns image public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException { if (!DataFlavor.imageFlavor.equals(flavor)) { throw new UnsupportedFlavorException(flavor); } return image; } } Exception in thread "main" java.lang.IllegalArgumentException: Width (-1) and height (-1) cannot be <= 0 at java.awt.image.DirectColorModel.createCompatibleWritableRaster(DirectColorModel.java:999) at sun.awt.datatransfer.DataTransferer.imageToStandardBytes(DataTransferer.java:1994) at sun.awt.windows.WDataTransferer.imageToPlatformBytes(WDataTransferer.java:267) at sun.awt.datatransfer.DataTransferer.translateTransferable(DataTransferer.java:1123) at sun.awt.windows.WDataTransferer.translateTransferable(WDataTransferer.java:163) at sun.awt.windows.WClipboard.setContentsNative(WClipboard.java:73) at sun.awt.datatransfer.SunClipboard.setContents(SunClipboard.java:93) at automateSignature.LoadToClipboard.main(LoadToClipboard.java:8) I have tried to find a place in the code where width and height can be specified, but have not succeeded. I also examined the properties of the jpg file and the w and h are specified.enter code here

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  • Mix of Arabic and English causes problems in JTextArea (Java)

    - by Dan
    I have a JTextArea which displays HTML of an Arabic web page. So it's essentially a mix of English and Arabic. In the JTextArea, with columns set to 30, certain text just disappears instead of wrapping properly. The weird thing is that if I copy the invisible text and paste it into Notepad, then I can see it in Notepad. If I change the number of columns to 40, everything displays fine. Any ideas?

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  • Java synchronized method lock on object, or method?

    - by wuntee
    If I have 2 synchronized methods in the same class, but each accessing different variables, can 2 threads access those 2 methods at the same time? Does the lock occur on the object, or does it get as specific as the variables inside the synchronized method? Example: class x{ private int a; private int b; public synchronized void addA(){ a++; } public synchronized void addB(){ b++; } } Can 2 threads access the same instance of class x performing x.addA() and x.addB() at the same time?

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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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  • Using XPath on String in Android (JAVA)

    - by Rav
    I am looking for some examples of using xpath in Android? Or if anyone can share their experiences. I have been struggeling to make tail or head of this problem :-( I have a string that contains a standard xml file. I believe I need to convert that into an xml document. I have found this code which I think will do the trick: public static Document stringToDom(String xmlSource) throws SAXException, ParserConfigurationException, IOException { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); return builder.parse(new InputSource(new StringReader(xmlSource))); } Next steps Assuming the code above is OK, I need to apply xpath to get values from cat: "/animal/mammal/feline/cat" I look at the dev doc here: http://developer.android.com/reference/javax/xml/xpath/XPath.html and also look online, but I am not sure where to start! I have tried to use the following code: XPathFactory xPathFactory = XPathFactory.newInstance(); // To get an instance of the XPathFactory object itself. XPath xPath = xPathFactory.newXPath(); // Create an instance of XPath from the factory class. String expression = "SomeXPathExpression"; XPathExpression xPathExpression = xPath.compile(expression); // Compile the expression to get a XPathExpression object. Object result = xPathExpression.evaluate(xmlDocument); // Evaluate the expression against the XML Document to get the result. But I get "Cannot be resolved". Eclipse doesn't seem to be able to fix this import. I tried manually entering: javax.xml.xpath.XPath But this did not work. Does anyone know any good source code that I can utilise, for Android platform? 1.5

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