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  • add two float values in java

    - by user1845286
    acually i try to add two float values in java like this import java.text.DecimalFormat; class ExactDecimalValue { final strictfp static public void main(String... arg) { float f1=123.00000f; float f2=124.00000f; float f3=f1+f2; System.out.println(f1+f2); System.out.println("sum of two floats:"+f3); /*my expected output is:247.00000 but comming output is:247.0 and 247*/ } } Now what i can do to get the value in this format:247.00000. please any one help me. Thanks & Regards venkatesh

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  • Generate regular expression to match strings from the list A, but not from list B

    - by Vlad
    I have two lists of strings ListA and ListB. I need to generate a regular expression that will match all strings in ListA and will not match any string in ListB. The strings could contain any combination of characters, numbers and punctuation. If a string appears on ListA it is guaranteed that it will not be in the ListB. If a string is not in either of these two lists I don't care what the result of the matching should be. The lists typically contain thousands of strings, and strings are fairly similar to each other. I know the trivial answer to this question, which is just generate a regular expression of the form (Str1)|(Str2)|(Str3) where StrN is the string from ListA. But I am looking for a more efficient way to do this. Ideal solution would be some sort of tool that will take two lists and generate a Java regular expression for this. Update 1: By "efficient", I mean to generate expression that is shorter than trivial solution. The ideal algorithm would generate the shorted possible expression. Here are some examples. ListA = { C10 , C15, C195 } ListB = { Bob, Billy } The ideal expression would be /^C1.+$/ Another example, note the third element of ListB ListA = { C10 , C15, C195 } ListB = { Bob, Billy, C25 } The ideal expression is /^C[^2]{1}.+$/ The last example ListA = { A , D ,E , F , H } ListB = { B , C , G , I } The ideal expression is the same as trivial solution which is /^(A|D|E|F|H)$/ Also, I am not looking for the ideal solution, anything better than trivial would help. I was thinking along the lines of generating the list of trivial solutions, and then try to merge the common substrings while watching that we don't wander into ListB territory. *Update 2: I am not particularly worried about the time it takes to generate the RegEx, anything under 10 minutes on the modern machine is acceptable

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  • Android Notepadv1 Tutorial - Persistent mNoteNumber?

    - by Chris L.
    So I did the Notepadv1 tutorial. It worked great. No problems. I would however like some explanation on why the mNoteNumber remembers the last number of the item I created. So the class starts as follows: public class Notepadv1 extends ListActivity { private int mNoteNumber = 1; That's fine, I understand that. The only other time the mNoteNumber variable is used is when you add an item it creates a note with that number and then increments it to the next number as follows: private void createNote() { String noteName = "Note " + mNoteNumber++; Those are the only two references to the variable mNoteNumber. When I press the Home button and then reopen the app, I add a new note but instead of adding a second "Note 1" it remembers that the last note I added as "Note 3" so it makes "Note 4". So I don't get it. Does Java/Android remember the last state of variables? If anyone could give me some explanation that would be great THANKS!

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  • How to implement button in a vector

    - by user1880497
    In my table. I want to put some buttons into each row that I can press. But I do not know how to do it public static DefaultTableModel buildTableModel(ResultSet rs) throws SQLException { java.sql.ResultSetMetaData metaData = rs.getMetaData(); // names of columns Vector<String> columnNames = new Vector<String>(); int columnCount = metaData.getColumnCount(); for (int column = 1; column <= columnCount; column++) { columnNames.add(metaData.getColumnName(column)); } // data of the table Vector<Vector<Object>> data = new Vector<Vector<Object>>(); while (rs.next()) { Vector<Object> vector = new Vector<Object>(); for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) { vector.add(rs.getObject(columnIndex)); } data.add(vector); } return new DefaultTableModel(data, columnNames); }

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  • How to create a String Array and link it to a Grade array

    - by user1861544
    I have a project that I need to create 2 Arrays, one to hold Student Names and one to hold Student Scores. The user inputs the size of the array, and the array needs to be sorted using BubbleSort (putting the high scores at the top). I have started the project, created the first array for scores, I have successfully done bubble sort and sorted the grades. Now I can't figure out how to make an array for Names, and once I do how do I make the names array correspond to the Grades array BubbleSort? Here is the code I have so far. import java.util.Scanner; public class Grades { public static void main(String[]args){ { Scanner UserIn = new Scanner(System.in); System.out.print( "How many students are there? " ); int[]GradeArray = new int[UserIn.nextInt()]; for( int i=0 ; i<GradeArray.length ; i++ ) { System.out.print( "Enter Grade for Student " + (i+1) + ": " ); GradeArray[i] = UserIn.nextInt(); } bubbleSort(GradeArray); for( int i : GradeArray ) System.out.println( i ); System.out.println(); } } private static void bubbleSort(int[]GradeArray){ int n = GradeArray.length; int temp = 0; String temp2; for(int i=0; i<n; i++){ for(int j=1; j<(n-i);j++){ if(GradeArray[j-1]<GradeArray[j]){ //swap temp=GradeArray[j-1]; GradeArray[j-1]=GradeArray[j]; GradeArray[j]=temp; } } } } } Also how do I change the grades to Double? I started with Int and when I try to change everything to double I get an error saying "Found Double, expected Int".

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  • Can I use my objects without fully populating them?

    - by LuckySlevin
    I have situation. I have to create a Sports Club system in JAVA. There should be a class your for keeping track of club name, president name and braches the club has. For each sports branch also there should be a class for keeping track of a list of players. Also each player should have a name, number, position and salary. So, I come up with this. Three seperate classes: public class Team { String clubName; String preName; Branch []branches; } public class Branch { Player[] players; } public class Player { String name; String pos; int salary; int number; } The problems are creating Branch[] in another class and same for the Player[]. Is there any simplier thing to do this? For example, I want to add info for only the club name, president name and branches of the club, in this situation, won't i have to enter players,names,salaries etc. since they are nested in each other. I hope i could be clear. For further questions you can ask.

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  • Java api to exiftool

    - by mujer-esponja
    Hi! I am interesting en parser the exiftool result with a java api or something like that. I have been researching, but i didn't find any example. For example, how could I get theese results in my java project?? ExifTool Version Number : 8.22 File Name : ExifTool.jpg Directory : t/images File Size : 24 kB File Modification Date/Time Etc.. I am looking forwar a 'how to' or something like that. Thanks in advance!

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  • Java Or C++ Or What???

    - by Kronass
    Hi, My friends and I are starting a new project and we are shifting from windows to linux (for some reasons) and all of us are .Net background. for the new platform I decided to go with Java since many parts are similar with .Net but my friend is insisting on C++ saying it is much faster very mature and working with it will not effect on the productivity and development speed. The project that we will work on it will have threading, extensive string and datetime manipulation, some socket programing and of-course work with RDBMS (MySql Or Postgre not decided yet). I have some fears with java since oracle acquired sun and these people will do anything to make money out of it. some have advised in python and ruby and I like python but don't know should I make it the default language in this project. the project is not web application and we will make services and executables. what do you think, if you have other opinion you very welcome. Hint: Mono is not an option

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  • Why can't I pass an object of type T to a method on an object of type <? extends T>?

    - by Matt
    In Java, assume I have the following class Container that contains a list of class Items: public class Container<T> { private List<Item<? extends T>> items; private T value; public Container(T value) { this.value = value; } public void addItem(Item item) { items.add(item); } public void doActions() { for (Item item : items) { item.doAction(value); } } } public abstract class Item<T> { public abstract void doAction(T item); } Eclipse gives the error: The method doAction(capture#1-of ? extends T) in the type Item is not applicable for the arguments (T) I've been reading generics examples and various postings around, but I still can't figure out why this isn't allowed. Eclipse also doesn't give any helpful tips in its proposed fix, either. The variable value is of type T, why wouldn't it be applicable for ? extends T?.

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  • Should I be backing up a webapp's data to another host continuously ?

    - by user196289
    I have webapp in development. I need to plan for what happens if the host goes down. I will lose some very recent session status (which I can live with) and everything else should be persistently stored in the database. If I am starting up again after an outage, can I expect a good host to reconstruct the database to within minutes of where I was up to ? Or seconds ? Or should I build in a background process to continually mirror the database elsewhere ? What is normal / sensible ? Obviously a good host will have RAID and other redundancy so the likelihood of total loss should be low, and if they have periodic backups I should lose only very recent stuff but this is presumably likely to be designed with almost static web content in mind, and my site is transactional with new data being filed continuously (with a customer expectation that I don't ever lose it). Any suggestions / advice ? Are there off the shelf frameworks for doing this ? (I'm primarily working in Java) And should I just plan to save the data or should I plan to have an alternative usable host implementation ready to launch in case the host doesn't come back up in a suitable timeframe ?

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  • Ant Junit tests are running much slower via ant than via IDE - what to look at?

    - by Alex B
    I am running my junit tests via ant and they are running substantially slower than via the IDE. My ant call is: <junit fork="yes" forkmode="once" printsummary="off"> <classpath refid="test.classpath"/> <formatter type="brief" usefile="false"/> <batchtest todir="${test.results.dir}/xml"> <formatter type="xml"/> <fileset dir="src" includes="**/*Test.java" /> </batchtest> </junit> The same test that runs in near instantaneously in my IDE (0.067s) takes 4.632s when run through Ant. In the past, I've been able to speed up test problems like this by using the junit fork parameter but this doesn't seem to be helping in this case. What properties or parameters can I look at to speed up these tests? More info: I am using the reported time from the IDE vs. the time that the junit task outputs. This is not the sum total time reported at the end of the ant run. So, bizarrely, this problem has resolved itself. What could have caused this problem? The system runs on a local disk so that is not the problem.

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  • How to get the parameter names of an object's constructors (reflection)?

    - by Tom
    Say I somehow got an object reference from an other class: Object myObj = anObject; Now I can get the class of this object: Class objClass = myObj.getClass(); Now, I can get all constructors of this class: Constructor[] constructors = objClass.getConstructors(); Now, I can loop every constructor: if (constructors.length > 0) { for (int i = 0; i < constructors.length; i++) { System.out.println(constructors[i]); } } This is already giving me a good summary of the constructor, for example a constructor public Test(String paramName) is shown as public Test(java.lang.String) Instead of giving me the class type however, I want to get the name of the parameter.. in this case "paramName". How would I do that? I tried the following without success: if (constructors.length > 0) { for (int iCon = 0; iCon < constructors.length; iCon++) { Class[] params = constructors[iCon].getParameterTypes(); if (params.length > 0) { for (int iPar = 0; iPar < params.length; iPar++) { Field fields[] = params[iPar].getDeclaredFields(); for (int iFields = 0; iFields < fields.length; iFields++) { String fieldName = fields[i].getName(); System.out.println(fieldName); } } } } } Unfortunately, this is not giving me the expected result. Could anyone tell me how I should do this or what I am doing wrong? Thanks!

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  • Output error in comparing characters from two strings

    - by Andrew Martin
    I'm stuck with my a piece of code I'm creating. My IDE is Eclipse and when I use its debugging feature, to trace what's happening on each line, it outputs perfectly. However, when I click the "run" project, it just outputs a blank screen: public static void compareInterests(Client[] clientDetails) { int interests = 0; for (int p = 0; p < numberOfClients; p++) { for (int q = 0; q < numberOfClients; q++) { String a = clientDetails[p].getClientInterests(); String b = clientDetails[q].getClientInterests(); int count = 0; while (count < a.length()) { if (a.charAt(count) == b.charAt(count)) interests++; count++; } if ((interests >= 3) && (clientDetails[p].getClientName() != clientDetails[q].getClientName())) System.out.print (clientDetails[p].getClientName() + " is compatible with " + clientDetails[q].getClientName()); interests = 0; } } } The code is designed to import an object array which contains information on a client's name and a client's interests. The client's interests are stored in the format "01010", where each 1 means they are interested in that activity, each 0 means they are not. My code compares each character of every client's string with every other client's string and outputs the results for all client's that don't have the same name and have three or more interests in common. When I run this code through Java's debugger, it outputs fine - but when I click run project or compile, I just get a blank screen. Any ideas?

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  • What is PHP like as a programming language?

    - by seanlinmt
    I am not really familiar with PHP, but I get the impression that it is like JavaScript (syntax-wise). What are the benefits of a dynamically typed language, when compared to a strongly typed language like C# or Java, and how would this help in the context of web development? What would make a dynamically typed language so attractive? Or, does the popularity of PHP have more to do with it being free? Okay, I think I better give a little more background to get more meaningful answers, because I am not wanting a flame war. I come from a C background, and when I moved into C# and Visual Studio. Having code completion, integration with an SQL database, huge existing class libraries and easy to access documentation, as well as new tools such as LINQ and ReSharper was like heaven. I didn't enjoy JavaScript before JQuery, but now I love it as well. Recently, I ported a PHP project over to C# and I used Zend to help me debug and understand more while porting - instead of maintaining two code streams. That also cut down on the cost of the server and maintenance. Getting into PHP would be nice. I think that Visual Studio has spoiled me - but again Eclipse is also equally spoiling. It would be nice to have an answer from someone who has experience developing both under PHP and .NET.

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  • Question about permute-by-sorting

    - by davit-datuashvili
    In the book "Introduction to Algorithms", second edition, there is the following problem: Suppose we have some array: int a[] = {1,2,3,4} and some random priorities array: P = {36,3,97,19} and the goal is to permute the array a randomly using this priorities array. This is the pseudo code: PERMUTE-BY-SORTING (A) 1 n ? length[A] 2 for i ? 1 to n 3 do P[i] = RANDOM (1, n 3) 4 sort A, using P as sort keys 5 return A The result should be the permuted array: B={2, 4, 1, 3}; I have written this code: import java.util.*; public class Permute { public static void main (String[] args) { Random r = new Random(); int a[] = new int[] {1,2,3,4}; int n = a.length; int b[] = new int[a.length]; int p[] = new int[a.length]; for (int i=0; i<p.length; i++) { p[i] = r.nextInt(n*n*n) + 1; } // for (int i=0;i<p.length;i++){ // System.out.println(p[i]); //} } } How do I continue?

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  • Refactoring huge if ( ... instanceof ...)

    - by Chris
    I'm currently trying to refactor a part of a project that looks like this: Many classes B extends A; C extends A; D extends C; E extends B; F extends A; ... And somewhere in the code: if (x instanceof B){ B n = (B) x; ... }else if (x instanceof C){ C n = (C) x; ... }else if (x instanceof D){ D n = (D) x; ... }else if (x instanceof E){ E n = (E) x; ... }else if (x instanceof G){ G n = (G) x; ... }... Above if-construct currently sits in a function with a CC of 19. Now my question is: Can I split this if-construct up in mutliple functions and let Java's OO do the magic? Or are there any catches I have to look out for? My idea: private void oopMagic(C obj){ ... Do the stuff from the if(x instanceof C) here} private void oopMagic(D obj){ ... Do the stuff from the if(x instanceof D) here} private void oopMagic(E obj){ ... Do the stuff from the if(x instanceof E) here} .... and instead of the huge if: oopMagic(x);

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  • Google App Engine/GWT/Eclipse Plugin Newbie Question- how to autobuild client side resources?

    - by Dieter Hanover
    Hi there, I'm tinkering with the default GWT application generated by the Google Eclipse plugin when I click the Google "New Web Application Project" button in Eclipse 3.5. This will no doubt be familiar to many of you.. basically there is an h1 title stating "Web Application Starter Project," a text field, and a Send button. What I've found is that whenever I make changes to the client side resources, e.g. change the text on the Send button to "Submit" in the .java file, Eclipse does not appear to autobuild these resources. In fact I have to rebuild the entire project in order for these changes to be reflected in my browser. I do have "build automatically" selected in eclipse. I should state that this is my second GWT project, the first was almost entirely server side (restlet on GAE) and everything built automatically nicely. When I first tried this new project with updated client resources, on refreshing my browser, the browser stated "you may need to (re)compile your project." I'm not sure if this is relevant but I thought I'd mention it all the same. So what's going on? How do I get Eclipse/GWT to autobuild these client side resources? Cheers for any help you can offer! :-)

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  • Space between 2 vertices on a heightmap

    - by Sietse
    First off, I am sorry for the crazy title. I couldn't really think of something else. I am working on a hobby project, it's a infinite world generated with Perlin Noise, Java and LWJGL. But I am having a problem, it is kinda hard to explain, so I made a video: http://youtu.be/D_NUBJZ_5Kw Obviously the problem is the black spaces in between all the pieces of ground. I have no idea what is causing it. I already tried making all the values doubles instead of floats, but that didn't fix it. Here is a piece of code I am using: float height2, height = (float)getHeight(x, y); height2 = (float) ((getHeight(x-1, y+1) + height) / 2); vertexhelper.addVertexColorAndTexture(x, height2, y+1, r, g, b, a, 0f, 1f); height2 = (float) ((getHeight(x+1, y+1) + height) / 2); vertexhelper.addVertexColorAndTexture(x+1, height2, y+1, r, g, b, a, 1f, 1f); height2 = (float) ((getHeight(x+1, y-1) + height) / 2); vertexhelper.addVertexColorAndTexture(x+1, height2, y, r, g, b, a, 1f, 0f); height2 = (float) ((getHeight(x-1, y-1) + height) / 2); vertexhelper.addVertexColorAndTexture(x, height2, y, r, g, b, a, 0f, 0f); I loop through this at the initialization of a chunk with x-16 and y-16. vertexhelper is a class I made that just puts everything in a array. (I am using floats here, but that's after doing the maths, so that shouldn't be a problem) I highly appreciate you reading this.

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  • Is my code a correct implementation of insertion sort?

    - by user1657171
    This code sorts correctly. Is this an insertion sort? import java.util.Scanner; public class InsertionSort { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter the number of elements: "); int count; count = sc.nextInt(); int[] a = new int[count]; System.out.println("Enter elements: "); for(int i = 0 ; i<count;i++){ a[i] = sc.nextInt(); } int j,temp; System.out.println("aftr insertion sort :"); for(int i = 1 ; i<count;i++){ j=i; while(j>0 && a[j-1] > a[j] ){ temp = a[j]; a[j] = a[j-1]; a[j-1] = temp; j--; } } for(int i = 0 ; i<count;i++){ System.out.print(a[i]+" "); } } }

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  • Storing same type but still getting an ArrayStoreException

    - by Firefoxx Pwnass
    I have strange problem. I have three classes. Book ( abstract ), and two subclasses ( Fiction, Nonfiction). I have created array of Book references. That array can hold both subclasse's objects. I'have following code for Fiction class. public class Fiction extends Book{ public Fiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 24.99; } } And the "same" code for Nonfiction class public class Nonfiction extends Book{ public Nonfiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 37.99; } } And this is Main program. import javax.swing.JOptionPane; public class Main { public static void main(String[] args) { Book[] book = new Fiction[6]; for(int i = 0; i<book.length; i++) { if(i<4) { String title = JOptionPane.showInputDialog("Enter fiction book, no "+i); book[i] = new Fiction(title); } else { String title = JOptionPane.showInputDialog("Enter non fiction book, no "+i); book[i] = new Nonfiction(title); } } for(int x = 0; x<book.length; x++) { System.out.println("Book named "+book[x].getTitle()+" costs "+book[x].getPrice()); } } } For any reason i'm getting ArrayStoreException on this line.. book[i] = new Nonfiction(title); But same code works for Fiction class. I checked java documentation and it says that this exception is thrown when i'm trying to store different objects in array ( like String and Int ), but in this case they are all the same objects. Both classes are children of superclass, that means, they are of the same type. I'm confsued. A little help here please?

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  • TCP socket communication

    - by raven
    hello, I am creating a Chat in java. I have a method (onMouseRelease) inside an object that creates a tcp server and waits for a socket like this: ServerSocket server = new ServerSocket(port); Socket channel = server.accept(); Now I want to make a thread that will loop and read data from the socket, so that once the user on the other side sends me a string, I will extract the data from the socket (or is it called packet? Sorry, I am new to this) and update a textbox to add the additional string from the socket (or packet?). I have no idea how to READ (extract) the information from the socket(/packet) and then update it into a JTextArea which is called userOutput. And how to send a string to the other client, so that it will also could read the new data and update its JTextArea. From what I know, for a 2 sided TCP communication you need one computer to host a server and the other to connect (as a client) and once the connection is set the client can also receive new information from the socket. Is that true? and please tell me how. Any help is appreciated! I know this is a bit long but I have searched a lot and didn't understand it (I saw something like PrintWriter but failed to understand).

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  • How i can fix the increasing order summation code?

    - by user2971559
    I want from the java to reads all numbers from the user as long as the number entered by user is bigger than the previous number. But i could write it for only positive numbers. How i can fix code below if all numbers included. If it is possible please write the solution for beginners because its my first year in computer science in college and I haven't learn a lot yet. import acm.program.*; public class IncreasingOrder extends ConsoleProgram { public void run() { int previousNumber = 0; int total = 0; int count = 0; while(true) { int n = readInt("Enter > "); if (n <= previousNumber) break; total += n; count++; previousNumber = n; } println("You have entered " + count + " numbers in increasing order."); println("Sum of these " + count + " numbers is " + total + "."); } }

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