Java 'while' Looping
Write a program to read the bicycle wheel radius (a "double") the number of teeth on the front sprocket (an "int") and then to read repeatedly the number of teeth on a rear sprocket (an "int") and compute and print the effective radius until a value of zero is encountered.
At every calculation except the first, print the ratio of the newly computed effective radius to the previous effective radius.
MY problem is how i can use while loop in it to make it zero. well i m going to try different way to use while loop inside to get value zero and then get ratio to work. any help would be usefull.I m learning...as well so i will try just need guide line if its possible.
Thanks all for reading
public class BicycleGears {
public static void main(String[] argv)
double wheelRadius=0.0f;
float eftRadius=0.0f;
int frontSprocket=0;
int rearSprocket=0;
float pRadius=-0.0f;
double eftRadius1;
float ratio=0.00f;
//Prompt and read the number;
System.out.println ("Please enter the wheelRadius");
wheelRadius = UserInput.readDouble();
//produce an error message and end program
if(wheelRadius <= 0)
System.out.println("Error, invalid value");
System.exit(0);
//Prompt and read the number;
System.out.println("Please enter the frontSprocket");
frontSprocket = UserInput.readInt();
//produce an error message and end program
if(frontSprocket <= 0)
System.out.println("Error, invalid value");
System.exit(0);
//Prompt and read the number
System.out.println("Please enter the rearSprocket");
rearSprocket = UserInput.readInt();
//produce an error message and end program
if (rearSprocket <= 0)
System.out.println("Error, invalid value");
System.exit(0);
// calculation for radius
eftRadius1 = (wheelRadius*frontSprocket)/rearSprocket;
//print radius
----------------------------------error-----------------------------
do {
System.out.println("The effective radius for radius" + wheelRadius + "and sprockets" + frontSprocket + " and " + rearSprocket + " is " + eftRadius1 );
} while (eftRadius1 > 0);
System.out.println("The effective radius for radius" + wheelRadius + "and sprockets" + frontSprocket + " and " + rearSprocket + " is " + eftRadius1 );
eftRadius1--;
--------------------------error-----------------------------------------
its work fine & run up to zero value But its start my calculation from E.g ( The effective radius for radius 27.5 and sprockets 55 and 23 is *65.77* Right ) But its give me result from here
The effective radius for radius 27.5 and sprockets 55 and 23 is *42.77* ( Wrong ) till it go 0.
} // end of main
} // end class
when i run i dont get any error thats the problem :)
but only if some one run the code then they can understand my problem
on above code my looping working fine but when i run, it give me wrong result. and Blue J dont give me any error..i asked teacher they said go & work out out yourself :( ...
anyway i m working on it...but really thanks for your time man.
------------------------------------------My result which is wrong ----------------------------------------
The effective radius for radius : 44.76087
The effective radius for radius : 43.76087
The effective radius for radius : 42.76087
The effective radius for radius : 41.76087
The effective radius for radius : 40.76087
The effective radius for radius : 39.76087
The effective radius for radius : 38.76087
The effective radius for radius : 37.76087
The effective radius for radius : 36.76087
The effective radius for radius : 35.76087
The effective radius for radius : 34.76087
The effective radius for radius : 33.76087
The effective radius for radius : 32.76087
The effective radius for radius : 31.760872
The effective radius for radius : 30.760872
The effective radius for radius : 29.760872
The effective radius for radius : 28.760872
The effective radius for radius : 27.760872
The effective radius for radius : 26.760872
The effective radius for radius : 25.760872
The effective radius for radius : 24.760872
The effective radius for radius : 23.760872
The effective radius for radius : 22.760872
The effective radius for radius : 21.760872
The effective radius for radius : 20.760872
The effective radius for radius : 19.760872
The effective radius for radius : 18.760872
The effective radius for radius : 17.760872
The effective radius for radius : 16.760872
The effective radius for radius : 15.760872
The effective radius for radius : 14.760872
The effective radius for radius : 13.760872
The effective radius for radius : 12.760872
The effective radius for radius : 11.760872
The effective radius for radius : 10.760872
The effective radius for radius : 9.760872
The effective radius for radius : 8.760872
The effective radius for radius : 7.760872
The effective radius for radius : 6.760872
The effective radius for radius : 5.760872
The effective radius for radius : 4.760872
The effective radius for radius : 3.760872
The effective radius for radius : 2.760872
The effective radius for radius : 1.7608719
The effective radius for radius : 0.7608719
ratio is 0.23912811
Please enter the Rear Sprocket
-----------------------------------------------------------right code should give me result ----------------------------------------------
The effective radius for radius : *65.77*
The effective radius for radius : 64.65
The effective radius for radius : 63.56 etc till i get zero value
The effective radius for radius : 0.7608719 should be 0.00
ratio is 0.23912811 how i hide ratio here i dont need show ration on first radius ( At every calculation except the first, print the ratio of the newly computed effective radius to the previous effective radius.)
Please enter the Rear Sprocket
I am trying to explain you. As such i dont get any error to run code..may b some calculation wrong or i m sure thats problem coming from looping. if you c first code i point error lines
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sir i have given lot of effort but i am not able to solve my problem either with notifiers or with occurence fn,probably i do not know how to use these synchronisation tools.
sir i am using datasocket read ,i am communicating with java but my problem is that bcz im using while loop to see if value has changed my labview consumes all the processors time ,sir i want a event like thing so that while loop is not in continuous loopHi Sam,
I want to pass along a couple of tips that will get you more and better response on this list.
1) There is an un-written rule that says more "stars" is better than just one star. Giving a one star rating will probably eliminate that responder from individuals that are willing to anser your question.
2) If someone gives you an answer that meets your needs, reply to that answer and say that it worked.
3) If someone suggests that you look at an example, DO IT! LV comes with a wonderful set of examples that demonstate almost all of the core functionality of LV. Familiarity with all of the LV examples will get you through about 80% of the Certified LabVIEW Developer exam.
4) If you have a question first search the examples for something tha
t may help you. If you can not find an example that is exactly what you want, find one that is close and post a question along the lines of "I want to do something similar to example X, how can I modify it to do Y".
5) Some of the greatest LabVIEW minds offer there services and advice for free on this exchange. If you treat them good, they can get you through almost every challenge that can be encountered in LV.
6) If English is not your native language, post your question in the language you favor. There is probably someone around that can help. "We're big, we're bad, we're international!"
Trying to help,
Welcome to the forum!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
Running java process in a while loop using Runtime.exec() hangs on solaris
I'm writting a multithreaded application in which I'll be starting multiple instances of "AppStartThread" class (given below). If I start only one instance of "AppStartThread", it is working fine. But if I start more than one instance of "AppStartThread", one of the threads hangs after some time (occasionaly). But other threads are working fine.
I have the following questions:
1. Is there any problem with starting a Thread inside another thread?. Here I'm executing the process in a while loop.
2. Other thing i noticed is the Thread is hanging after completing the process ("java ExecuteProcess"). But the P.waitFor() is not coming out.
3. Is it bcoz of the same problem as given in Bug ID : 4098442 ?.
4. Also java 1.2.2 documentation says:
"Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock. "
I'm running this on sun Solaris/java 1.2.2 standard edition. If any of you have experienced the same problem please help me out.
Will the same problem can happen on java 1.2.2 enterprise edition.?
class AppStartThread implements Runnable
public void run()
while(true)
try
Process P=Runtime.getRuntime().exec("java ExecuteProcess");
P.waitFor();
System.out.println("after executing application.");
P.destroy();
P = null;
System.gc();
catch(java.io.IOException io)
System.out.println("Could not execute application - IOException " + io);
catch(java.lang.InterruptedException ip)
System.out.println("Could not execute application - InterruptedException" + ip);
catch (Exception e)
System.out.println("Could not execute application -" + e.getMessage());I'm writting a multithreaded application in which I'll
be starting multiple instances of "AppStartThread"
class (given below). If I start only one instance of
"AppStartThread", it is working fine. But if I start
more than one instance of "AppStartThread", one of the
threads hangs after some time (occasionaly). But other
threads are working fine.
I have the following questions:
1. Is there any problem with starting a Thread inside
another thread?. Here I'm executing the process in a
while loop.Of course this is OK, as your code is always being run by one thread or another. And no, it doesn't depend on which thread is starting threads.
2. Other thing i noticed is the Thread is hanging
after completing the process ("java ExecuteProcess").
But the P.waitFor() is not coming out.This is a vital clue. Is the process started by the Runtime.exec() actually completing or does the ps command still show that it is running?
3. Is it bcoz of the same problem as given in Bug ID :
4098442 ?.
4. Also java 1.2.2 documentation says:
"Because some native platforms only provide limited
ed buffer size for standard input and output streams,
failure to promptly write the input stream or read the
output stream of the subprocess may cause the
subprocess to block, and even deadlock. "These two are really the same thing (4098442 is not really a bug due to the reasons explained in the doc). If the program that you are exec'ing produces very much output, it is possible that the buffers to stdout and stderr are filling preventing your program from continuing. On Windows platforms, this buffer size is quite small (hundreds of characters) while (if I recall) on Solaris it is somewhat larger. However, I have seent his behavior causing problem on Solaris 8 in my own systems.
I once hit this problem when I was 'sure' that I was emitting no output due to an exception being thrown that I wasn't even aware of - the stack trace was more than enough to fill the output buffer and cause the deadlock.
You have several options. One, you could replace the System.out and System.err with PrintStream's backed up by (ie. on top of) BufferedOutputStream's that have large buffers (multi-K) that in turn are backed up by the original out and err PrintStream's. You would use System.setErr() and System.setOut() very early (static initializer block) in the startup of your class. The problem is that you are still at the mercy of code that may call flush() on these streams. I suppose you could implement your own FilterOutputStream to eat any flush requests...
Another solution if you just don't care about the output is to replace System.out and System.err with PrintStreams that write to /dev/nul. This is really easy and efficient.
The other tried and true approach is to start two threads in the main process each time you start a process. These will simply consume anything that is emitted through the stdout and stderr pipes. These would die when the streams close (i.e. when the process exits). Not pretty, but it works. I'd be worried about the overhead of two additional threads per external process except that processes have such huge overhead (considering you are starting a JVM) that it just won't matter. And it's not like the CPU is going to get hit much.
If you do this frequently in your program you might consider using a worker thread pool (see Doug Lea's Executor class) to avoid creating a lot of fairly short-lived threads. But this is probably over-optimizing.
Chuck -
Ending Java War game with while loop
How would i go about ending a java war game witha while loop. I want the program to run until all of the values of one of the arrays of one of the players split decks has all null values.
GameObject[] theArrayInQuestion;
// populate array somehow or other
void methodWithLoop() {
while(arrayNotNull(theArrayInQuestion)) {
// do stuff
boolean arrayNotNull(Object[] array) {
int len = array.length;
for(int i = 0; i < len; i++) {
if ( array[i] != null ) {
return true;
return false
} -
Using while loops instead of for loops in arrays?
I am new to java and doing a java tutorial on using arrays and for loops. What im trying to find out is how it is possible to use a while loop instead.
I would be very grateful if anyone can suggest a way of changing my code to use a while loop.
The code I have written is:
public class DetermineGrade
public static void main(String[]args)
final char[] mark = {'A','B' ,'C' ,'D' ,'F' };
char [] grade = new char[5];
int [] Score ={95,35,65,75};
for (int i=0; i<4; i++)
if (Score >= 90)
grade= mark[0] ;
else if (Score >=80)
grade = mark[1] ;
else if (Score >=70)
grade = mark[2] ;
else if (Score >=60)
grade = mark[3];
else grade = mark[4];
for (int i=0; i<4; i++)
System.out.println("grade = " + Score + ", " + grade);
Thankyou LBIm trying to underdstand the differences in the
different loops. I can grasp the for loop but I dont
see how a while loop works, or how it id different
from the other?
for (j = INIT; j < MAX; j++) {
// do stuff
}is the same as
j = INIT;
while (j < MAX) {
// do stuff
j++;
}Lee -
Can't break out of a while loop
Hi, I am doing a networking course, for which an assignment was to write an echo client and server. I did the assignment in Java and it works just fine. However, there is something I don't understand that is bugging me. I wanted a way to stop the server by either detecting when the client entered "quit" or when the user of the server entered "quit". This was not part of the assignment, but after trying many different things I really want to know (1) what I am doing wrong and (2) what the correct way to do things would be.
I tried to put an "if" clause within the while loop so that if the client entered "quit" the server would detect that, close the socket connections, and break the while loop. But... it seems that I have done this wrong and I am not sure why.
(Note - I am not a Java programer - just a beginner, and the course in question isn't a programming course. I did the program below by following some brief guidelines/tutorial. I don't even have any books on Java to consult right now - just ordered few from Amazon for any future projects.)
The code:
// EchoServer.java - a simple server program. It listens on a predetermined port for an incoming connection.
// After a client connects they can input a line of text and
// the server will echo the exact same line back.
import java.io.*;
import java.net.*;
public class EchoServer {
protected static int DEFAULT_PORT = 3004;
public static void main (String args[]) throws Exception {
int portNumber;
try {
portNumber = Integer.parseInt(args[0]);
} catch (Exception e) {
portNumber = DEFAULT_PORT;
ServerSocket myServer = null;
try{
myServer = new ServerSocket(portNumber);
System.out.println("Echo Server started. Listening on port " + portNumber);
} catch (IOException e) {
System.out.println("Could not listen on port: " + portNumber);
System.out.println(e);
Socket clientSocket = null;
try{
clientSocket = myServer.accept();
} catch (IOException e) {
System.out.println("Accept failed: " + portNumber);
System.out.println(e);
BufferedReader input = null;
PrintWriter output = null;
try {
input = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
output = new PrintWriter(clientSocket.getOutputStream(), true);
} catch (IOException e) {
System.out.println(e);
String theLine;
while(true){
theLine = input.readLine();
output.println(theLine);
output.flush();
if (theLine.equals("quit")) {
input.close();
output.close();
clientSocket.close();
myServer.close();
break;
} // end if
} // end while
} // end main
} // end EchoClientA few observations:
- You might as well exit after you have caught your exceptions, since none of the conditions I see would allow your program to run properly afterwards. You can either do that by a System.exit(int) or a return;
- Although this s an example program, you should take advantage of doing things right. Addining a try-finally would be good for tidying things up. First declare your variables before the main try, otherwise the finally won't be able to do its job. For example (this won't compile as is):
Socket clientSocket = null;
ServerSocket myServer = null;
InputStream in = null;
OutputStream out =null;
try {
String theLine = null;
while( (theLine = input.readLine()) != null ){
output.println(theLine);
output.flush();
if (theLine.equals("quit")) {
break;
} // end while
} catch ( IOException ex ) {
ex.printStackTrace();
} finally {
if ( in != null ) {
in.close();
if ( out != null ) {
out.close();
// add other conditions to close other closeable objects
}The reasoning is that if an exception were ever to happen you would be sure that the clean up would be done. In your current example you may risk having an inputstream left open. Also note that BufferedReader.readLine() returns null when its arrived at the end of its content. -
Getting a for loop inside a while loop
I've been having problems with the code below. I'm trying to get the 'while' loop to work so that the program will continue to run after a user types in a sentence. This is supposed to print out how many times a letter has been typed when a sentence has been put in, but it's not working right. It just keeps adding the first sentences numbers together even when a new sentence is typed out. I don't know what I'm doing wrong with this 'while' loop.
import java.util.Scanner;
import java.util.*;
public class Count
public static void main (String[] args)
String phrase; // a string of characters
int countBlank; // the number of blanks (spaces) in the phrase
int length; // the length of the phrase
int countA = 0; // the number of a's in the phrase
int countT = 0; // the number of t's in the phrase
int countE = 0;
int countS = 0;
char ch; // an individual character in the string
Scanner scan = new Scanner(System.in);
// Print a program header
System.out.println ();
System.out.println ("Character Counter");
System.out.println ();
// Read in a string and find its length
System.out.println ("Enter a sentence or phrase ('quit' to quit): ");
phrase = scan.nextLine();
length = phrase.length();
// Initialize counts
countBlank = 0;
// a while loop to allow user to keep entering phrases
while (true)
String line=scan.nextLine();
System.out.println("Type quit to quit or enter a new phrase.");
if(line.equals("quit"))
break;
// a for loop to go through the string character by character
// and count the blank spaces
for(int i = 0; i < phrase.length(); i++)
ch = phrase.charAt(i);
switch (ch)
case ' ': countBlank++;
break;
case 'a':
case 'A': countA++;
break;
case 't':
case 'T': countT++;
break;
case 'e':
case 'E': countE++;
break;
case 's':
case 'S': countS++;
break;
// Print the results
System.out.println ();
System.out.println ("Number of blank spaces: " + countBlank);
System.out.println ("Number of A's: " + countA);
System.out.println ("Number of T's: " + countT);
System.out.println ("Number of E's: " + countE);
System.out.println ("Number of S's: " + countS);
System.out.println ();
}Ok well I don't really understand what you're saying, but here's an improved version of my code and I can get it to work, but I don't know how to turn the "do while" loop into just a "while" loop.
import java.util.Scanner;
public class Count3
public static void main (String[] args) {
String phrase; // a string of characters
int countBlank=0; // the number of blanks (spaces) in the phrase
int length; // the length of the phrase
char ch; // an individual character in the string
int countA=0;
int countE=0;
int countS=0;
int countT=0;
String quit = new String("quit"); //String wasn't initialized
Scanner scan = new Scanner(System.in);
// Print a program header
System.out.println ();
System.out.println ("Character Counter");
System.out.println ();
do { //do-while loop
// Read in a string and find its length
System.out.println("Enter a sentence or phrase, or type \"quit\" to quit: ");
phrase = scan.nextLine();
length = phrase.length();
// a for loop to go through the string character by character
// and count the blank spaces, a's, e's, s', and t's
for (int i = 0; i <= length-1; i++) {
ch = phrase.charAt(i);
switch (ch) {
case ' ': countBlank++;
break;
case 'a':
case 'A': countA++;
break;
case 'e':
case 'E': countE++;
break;
case 's':
case 'S': countS++;
break;
case 't':
case 'T': countT++;
break;
// Print the results
System.out.println ();
System.out.println ("Number of blank spaces: " + countBlank);
System.out.println ("Number of a's: " + countA);
System.out.println ("Number of e's: " + countE);
System.out.println ("Number of s's: " + countS);
System.out.println ("Number of t's: " + countT);
System.out.println ();
countA=0; countE=0; countS=0; countT=0; countBlank=0;
}while (!(phrase.equalsIgnoreCase(quit)));
}//end main
}//end class Count -
Incorporate: For, and while loop,a nested pair for both,and to add graphics
// I have done the class but
need help one adding one while loop, one for loop, and a nested pair loops using for and while, and if posbile to add on a dynamite graphics. // i am doing this for a brithday present for my brother who is a java programer
and would be happy to see his little brother make a java programe for him
//class file
import java.awt.*;
public class ZZZCalculator
private double amount;
public ZZZCalculator (double x)
amount= x;
public void addAmt (double inputNumber)
amount= amount +inputNumber;
public void divideAmt (double inputNumber)
amount=amount/inputNumber;
public void subtractAmt (double inputNumber)
amount=amount-inputNumber;
public void multiplyAmt (double inputNumber)
amount=amount*inputNumber;
public void display (Graphics g)
g.drawString (""+ amount, 150,100);
public void setAmt(double x)
amount= x;
// Pgm file
import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class ZZZCalc extends Applet implements ActionListener {
ZZZCalculator henrietta;
TextField amtPlace;
Button adder;
Button divide;
Button subtract;
Button multiply;
public void init()
henrietta=new ZZZCalculator(0.0);
amtPlace=new TextField(10);
amtPlace.addActionListener(this);
add(amtPlace);
adder=new Button ("+");
adder.addActionListener(this);
add(adder);
divide=new Button ("/");
divide.addActionListener(this);
add(divide);
subtract=new Button ("-");
subtract.addActionListener(this);
add(subtract);
multiply=new Button ("*");
multiply.addActionListener(this);
add(multiply);
public void paint (Graphics g)
g.drawString("amount:", 100,100);
henrietta.display(g);
public void actionPerformed(ActionEvent e)
if (e. getSource()==amtPlace)
double amt= Double.parseDouble (amtPlace.getText());
henrietta.setAmt(amt);
repaint();
if(e.getSource()==adder)
double amt= Double.parseDouble (amtPlace.getText());
henrietta.addAmt(amt);
repaint();
if(e.getSource()==divide)
double amt= Double.parseDouble (amtPlace.getText());
henrietta.divideAmt(amt);
repaint();
if(e.getSource()==subtract)
double amt= Double.parseDouble (amtPlace.getText());
henrietta.subtractAmt(amt);
repaint();
if(e.getSource()==multiply)
double amt= Double.parseDouble (amtPlace.getText());
henrietta. multiplyAmt(amt);
repaint();
//thank you for the help
i have just started working on java and this is my frist program i am working on and any help i can get would inprove my understanding of java.
Thank you very much for you helphey there... this is Rebecca
try this somewhere in the prog.
n = Math.pow(x,y)
where n is an int you declare...
and x and y are the numbers... as in
n = 10^3
where 10 = x and 3 = y -
Problem with while loop in thread: starting an audiostream
Hello guys,
I'm doing this project for school and I'm trying to make a simple app that plays a number of samples and forms a beat, baed on which buttons on the screen are pressed, think like fruity loops. But perhaps a screenshot of my unfnished GUI makes things a bit more clear:
[http://www.speedyshare.com/794260193.html]
Anyway, on pressing the play button, I start building an arraylist with all the selected samples and start playing them. Once the end of the "screen" is reached it should start playing again, this is the while loop:
public void run(){
//System.out.println("Wavfiles.size =" + getWavfiles().size());
System.out.println(repeatperiod);
if (getWavfiles() == null) {
System.out.println("Error: list of Wavfiles is empty, cannot start playing.");
else{
if(!active) return;
while(active){
System.out.println("Wavfiles.size =" + getWavfiles().size());
for (int i=0; i<getWavfiles().size(); i++){
Wavplayer filePlayer = new Wavplayer(getWavfiles().get(i).getStream());
Timer timer = new Timer();
//timer.scheduleAtFixedRate(filePlayer, getWavfiles().get(i).getStartTime(),repeatperiod);
timer.schedule(filePlayer, getWavfiles().get(i).getStartTime());
try {
Thread.sleep(repeatperiod);
} catch (InterruptedException ex) {
Logger.getLogger(LineBuilder.class.getName()).log(Level.SEVERE, null, ex);
}But once the second iteration should begin, I'm getting nullpointerexceptions. These nullpointerexceptions come exactly when the second period starts so I suppose the sleep works :-) The nullpointerexception comes from the wavfile I try to play. Wavfile class:
package BeatMixer.audio;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.TimerTask;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
import javax.sound.sampled.UnsupportedAudioFileException;
public class Wavplayer extends TimerTask {
private SourceDataLine auline;
private AudioInputStream audioInputStream;
private final int EXTERNAL_BUFFER_SIZE = 524288; // 128Kb
public Wavplayer(ByteArrayInputStream wavstream) {
try {
audioInputStream = AudioSystem.getAudioInputStream(wavstream);
} catch (UnsupportedAudioFileException e1) {
e1.printStackTrace();
return;
} catch (IOException e1) {
e1.printStackTrace();
return;
AudioFormat format = audioInputStream.getFormat();
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
try {
auline = (SourceDataLine) AudioSystem.getLine(info);
auline.open(format);
} catch (LineUnavailableException e) {
e.printStackTrace();
return;
} catch (Exception e) {
e.printStackTrace();
return;
@Override
public void run() {
System.out.println(auline);
auline.start();
int nBytesRead = 0;
byte[] abData = new byte[EXTERNAL_BUFFER_SIZE];
try {
while (nBytesRead != -1) {
nBytesRead = audioInputStream.read(abData, 0, abData.length);
if (nBytesRead >= 0)
auline.write(abData, 0, nBytesRead);
} catch (IOException e) {
e.printStackTrace();
return;
} finally {
auline.drain();
auline.close();
}auline is null on second iteration, in fact, getAudioInputStream doesn't really work anymore, and I don't know why because I don't change anything about my list of wavfiles as far as I know... Any thoughts or extra info needed?
Edited by: Lorre on May 26, 2008 12:22 PMIs my question not clear enough? Do you need more info? Or is nobody here familiar with javax.sound.sampled?
Edited by: Lorre on May 26, 2008 2:07 PM -
Hi guys,
i'm doing a pass exam java question, below is the question criteria.
Write a program that allows a user to enter their mark attained in each unit and displays their grade. After all marks are entered the average mark is displayed.
The main method should:
Prompt the user to enter the number of units taken (check for NumberFormatException)
Write a for loop to repeat for each subject, where each iteration
Prompts the user to enter a mark ( a double) for unit 1, unit 2 etc. This should be in a while loop so if mark entered is less than 0 or greater than 100 the prompt will be repeated.
Pass the mark to a method called getGrade.
Display the returned grade
Accumulate each mark
Print the average mark to 2 decimal places
The getGrade method should:
Accept the parameter passed from the main method
Determine the grade according to the following scale
Return the grade
The words that i highlighted in bold is the criteria.
As you can see from the above question, i create an array , even though the question does not prompt me to create as what i know from tackling JavaQuestions "if it does not prompt me to add a criteria, it is ok to add it" :)
below is my program code , in which the result i get is the same as the question result. BUT, from the above question it ask me to add a while loop, so if mark entered is less than 0 or greater than 100 the prompt will be repeated.
But instead i use a do loop. :(
so can anyone help me or show me how to create the while loop for mark entered is less than 0 or greater than 100 the prompt will be repeated, from my program code below. cause i want to know whether it possible to have a while loop instead of do loop for the my program and the while loop can work with an array criteria.
thanks
htw.
import javax.swing.*;
import java.text.DecimalFormat;
public class Mark
public static void main (String [] args)
String unitStr;
String markEnterStr;
int validUnit;
double total = 0;
boolean validInput = true;
DecimalFormat fmt = new DecimalFormat("#0.00");
while (validInput)
unitStr = JOptionPane.showInputDialog(null,"Enter number of units: ");
try
validUnit = Integer.parseInt(unitStr);
double[] markArray = new double[validUnit];
validInput = false;
for (int index = 0;index < validUnit; index++)
do
markEnterStr = JOptionPane.showInputDialog("Please enter mark " +(index+1) +":");
markArray[index] = Double.parseDouble(markEnterStr);
while(markArray[index] < 0 || markArray[index] >100);
String correctMark = getGrade(markArray[index]);
System.out.println(correctMark);
total = total + markArray[index];
double average = (double)total / validUnit;
System.out.println("Average = " +fmt.format(average));
catch (NumberFormatException e)
public static String getGrade(double x)
String grade;
if (x < 50)
grade = "Fail";
else if (x < 60)
grade = "Pass";
else if (x < 70)
grade = "Credit";
else if (x < 80)
grade = "Distinction";
else grade = "High distinction";
return grade;
}Hope u got it.
markArray[index] = -1;
while(markArray[index] < 0 || markArray[index] >100);
markEnterStr = JOptionPane.showInputDialog("Please enter mark " +(index+1) +":");
markArray[index] = Double.parseDouble(markEnterStr);
}VJ -
I am new to Java and need some assistance with the following program:
Write a program that asks for the user's name and then writes that name to the monitor with either "Ms." or "Mr." in front, depending if the name is for a female or male. Assume that the only female names are
* Amy
* Buffy
* Cathy
and that the only male names are
* Elroy
* Fred
* Graham
All other names will be echoed without a title. The program continues looping until the user hits "enter" without first typing a name.
C:\>java Title
Enter a name:
Amy Johnson
Ms. Amy Johnson
Enter a name:
Fred Smith
Mr. Fred Smith
Enter a name:
Zoltan Jones
Zoltan Jones
Enter a name:
C:\>
Hints: Use a Scanner to read user input. Uses a while loop that tests the length of the input line. Use startsWith() to test the names.
Here's what I have so far:
import java.util.*;
public class TitleApplier
* @param args
public static void main(String[] args)
Scanner scan = new Scanner (System.in);
System.out.println ("Please enter your name:");
String name = scan.nextLine();
while (name.startsWith("A"))
System.out.println ("Ms. ".concat (name));
if (name.startsWith ("B"))
System.out.println ("Ms. ".concat (name));
if (name.startsWith ("C"))
System.out.println ("Ms. ".concat (name));
if (name.startsWith ("E"))
System.out.println ("Mr. ".concat (name));
if (name.startsWith ("F"))
System.out.println ("Mr. ".concat (name));
if (name.startsWith ("G"))
System.out.println ("Mr. ".concat (name));
else
System.out.println (name);
Here are the problems are I am having:
I am asked to use a while loop that tests the length of the input, I am not sure how I would go about doing that.
When I enter Amy the program keeps looping, but it does not do that for any other name.
When I enter any of the other names, I get two outputs one with a title and one right below that with out the title. Is there a way to get one output, the one with the title?ChavezOA wrote:
I am asked to use a while loop that tests the length of the input, I am not sure how I would go about doing that.
When I enter Amy the program keeps looping, but it does not do that for any other name. You need to familiarize yourself with logic statments... specifically the use of or "||" also and "&&"... (condition1) || (condition2) || ...
When I enter any of the other names, I get two outputs one with a title and one right below that with out the title. Is there a way to get one output, the one with the title?As already stated, you have independent "if" statements, you need to link them together somehow...
if() {
//what ever
else if() {
//what ever
else if() {
//what ever
} -
Question in ABAP syntax, read & insert data from internal table, while loop
Hi, SDN Fellow.
I am from Java background and learnt ABAP, I don't usually write much ABAP code.
I am trying to implement the following logic in a RFC now.
I have one z-custom database table, the structure as the following:
It has two columns, with these sample data.
Says datable table is ZEMPMGRTAB.
EmployeeID,ManagerID
user10,user1
user9,user1
user8,user1
user7,user2
user6,user2
user5,user2
user4,user2
user2,user1
The logic is this:
I have a input parameter, userid. I am using this parameter to have a select statement to query the record into export table,EXPTAB 'LIKE' table ZEMPMGRTAB.
SELECT * FROM ZEMPMGRTAB
into table EXPTAB
WHERE EMPLOYEEID = USERID.
Say, my parameter value, USERID ='USER4'.
Referring to the sample data above, I can get the record of this in my EXPTAB,
EmployeeID,ManagerID
user4,user2
Now, I want to iterately use the EXPTABLE-ManagerID
as the USERID input in SELECT statement, until it has no return result. Then, insert the new records in
EXPTAB.
In above new loop case, we will get this table content in EXPTAB,
EmployeeID,ManagerID
user4,user2
user2,user1
I kind of think of the pseudocode logic as below:
(These may not be a valid ABAP code, so I need help to convert/correct them)
DATA:
IWA TYEP ZZEMPMGRTAB,
ITAB
HASHED TABLE OF ZZEMPMGRTAB
WITH UNIQUE KEY EMPLOYEEID.
SELECT * FROM ZEMPMGRTAB
into table ITAB
WHERE EMPLOYEEID = USERID.
*Question 1: I cannot insert a internal table to export table, it is *incompatible type, what is the alternative way fo this?
*Question 2: How can I access thedata of the internal table like this,ITAB-MANAGERID? As if I can, I would do this:
* IWA-EMPLOYEEE = ITAB-EMPLOYEEID. IWA-MANAGERID = IWA-MANAGERID. INSERT IWA INTO TABLE EXPTAB.
* Question 3: Is the 'NE NULL' - 'not equal to NULL' is right syntax?
IF ITAB NE NULL.
INSERT ITAB INTO EXPTAB.
ENDIF
* Question 4: Is my WHILE loop setup right here? And are the syntax right?
WHILE ITAB NE NULL.
SELECT * FROM ZEMPMGRTAB
into table ITAB
WHERE EMPLOYEEID = ITAB-MANAGERID.
IF ITAB NE NULL.
INSERT ITAB INTO EXPTAB.
ENDIF
REFRESH ITAB.
ENDWHILE.
Assume all the syntax and logic are right, I should get this result:
EmployeeID,ManagerID
user4,user2
user2,user1
If I have a new entry in datable table,ZEMPMGRTAB like this:
user1,user0
My pseudocode logic will get this result:
EmployeeID,ManagerID
user4,user2
user2,user1
user1,user0
I truly appreciate if you can help me to validate the above syntax and pseudocode logic.
Thanks in advance.
KCHi,
FUNCTION ZGETSOMEINFO3.
*"*"Local Interface:
*" IMPORTING
*" VALUE(USERID) TYPE AWTXT
*" VALUE(FMTYPEID) TYPE AWTXT
*" EXPORTING
*" VALUE(RETURN) TYPE BAPIRETURN
*" TABLES
*" APPROVERT STRUCTURE ZTAB_FMAPPROVER
*" ACTOWNERT STRUCTURE ZTAB_FMACTOWNER
DATA: T_RESULT TYPE STANDARD TABLE OF ZTAB_FMAPPROVER.
**Question 1: For this line, I got an error says "Program ''USERID" *not found. Is the syntax right, as the USERID is a parameter for the function.
perform add_line(USERID).
ENDFUNCTION.
form add_line using i_user type ZTAB_FMAPPROVER.EMPLOYEEID
changing T_RESULT TYPE ZTAB_FMAPPROVER.
data: ls_row type ZTAB_FMAPPROVER.
* Get record for i_user
select single * into ls_row from ZTAB_FMAPPROVER
where EmployeeID = i_user.
if sy-subrc NE 0.
* Do nothing, there is not manager for this employee
else.
* Store result
QUESTION 2: I am still got stuck on this line of code. It still *says that "T_RESULT" is not an internal table "OCCURS n" *specification is missing. I thought the line: "T_RESULT TYPE *ZTAB_FMAPPROVER" means declare internal table, T_RESULT as type of ZTAB_FMAPPROVER". Am I understand it wrongly?
append ls_row to t_result.
* Call recursion
perform add_line using ls_row-ManagerID
changing t_result.
endif.
endform.
Thanks,
KC -
Hi...I am somewhat new to Java and I am trying to do a nested while loop. Basically I have a result set from a query and I want to loop though that result set BUT I need a second loop to put together 150 of the results at a time and add them to a GeoCodeRequest to send to MapInfo.....this is how I think the code should look, I need some advice if it is the proper way to loop through....
ArrayList aal = new ArrayList();
ServiceMessage sm = new ServiceMessage();
ServiceMessage rsm = new ServiceMessage();
while (rset.next())
statRecord = statRecord + currentRecord;
while (rset.next() && currentRecord <= 150)
AddressEx a = new AddressEx(rset.getString(6));
ContentColumn cc = new ContentColumn("mmhid");
cc.setValue(rset.getString(1));
StreetAddress streetAddress = new StreetAddress(rset.getString(3));
streetAddress.setBuildingName(rset.getString(2));
a.setCountrySubdivision(rset.getString(5));
a.setMunicipality(rset.getString(4));
a.setPostalCode(rset.getString(6));
a.setContentColumn(0,cc);
aal.add(a);
currentRecord++;
System.out.println("Inside inner while loop now..");
System.out.println("Add 150 to request...");
GeocodeRequestEx gr = new GeocodeRequestEx("","3.0","id",(AddressEx[])aal.toArray());
gr.setGeocodePreference(pref);
sm.addRequest(gr);
System.out.println("going to geocode now...");
try{
LocationUtilityServiceLocator lus = new LocationUtilityServiceLocator();
LocationUtility lu = lus.getLocationUtility(new URL(url));
XLSType xr = lu.perform(sm.toXLS());
rsm = new ServiceMessage(xr);......
code goes on to do oter things but this is the basis..............
I hope that all made since.....please help.I am not sure if there is a problem, that is what I am
asking......if I have the logic correct.
I haven't been able to test it correct because I am
getting an:
Exception in thread "main"
java.lang.ClassCastException: [Ljava.lang.Object; at
geoClient.main(geoClient.java:127)
That means you don't have it correct. :-)> on the following line:> > GeocodeRequestEx gr = new> GeocodeRequestEx("","3.0","id",(AddressEx[)aal.toArray
and I haven't figured out to correct that yet......You need to use toArray(Object[]). -
Hello,
I have a question on object creation and while loops. Have a look at the following code snippet:
while(true)
Object obj = new Object();
// Pass off obj to a new thread
Thread job = new Thread(new ObjectHandler(obj));
job.start();
}My question is, do I have to wait until the newly created Thread is finished with the Object obj before I can create a new Object called obj in the while loop?
Also does anyone have any documentation on this sort of thing?
Thanks,
Tony.Jaxie wrote:
I'm still not sure you get what I'm on about, you might want to read up on java methods and pass by value.I think we know how it works. Most of us have been programming in Java for serveral years.
>
When you pass an object to a method in java you pass it a copy of a reference to that object. Leading on from that, before an object is eligible for garbage collection in java, all references to that object must be dropped.
So with all that in place, my question was, is the creation of an object in a while loop dependent on previous objects of the same name? Objects don't have names. Have we mentioned that before?
You have a reference, larry that is referencing an unnamed object. You can also create other references that reference the same object. The thread will have one reference. You can then make larry reference another object. That will not change anything in the thread. It will still reference the old object, and that object will not be claimed by the gc until that thread stops referencing it.
So the second time we go through the loop below, do we have to wait until larry has been garbage collected, before a new larry can be created?Read the articles/tutorials and what I have written above. What do you think?
Do also note that the GC isn't executed synchronously. -
I'm very new to java so please bear with me!!!
This is my code:
import java.io.*;
public class IfExample2
public static void main (String[] args) throws IOException
// Read in a number
BufferedReader br = new BufferedReader(
new InputStreamReader (System.in));
System.out.print ("Enter a number between 0 and 10 inclusive: ");
String temp = br.readLine();
double x = Double.parseDouble(temp);
// check user input
if (x > 10)
System.out.println("The number you entered is too high");
System.out.println("Please re-enter the number");
else if (x < 0)
System.out.println("The number you entered is too low");
System.out.println("Please re-enter the number");
else
System.out.println("The number you entered is " + x);
}Basically I want, if the number entered is too high or too low I want it to ask the user to re-enter the number, I want to use a while loop but I'm not sure where or how to use it, please help!while ( condition ) {
// stuff here
}More on while: [http://java.sun.com/docs/books/tutorial/java/nutsandbolts/while.html|http://java.sun.com/docs/books/tutorial/java/nutsandbolts/while.html]
Edited by: oscarjustesen on Oct 7, 2008 5:40 PM
Edited - fixed link
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