Thread: Need help with loop

So i got this assignment in computer science that computes change from money given etc. etc.

Anyways what i need help with is at the end of the program it asks you if you want to run the program again. I got it to run it again one more time with an if statement but it only runs on more time and it runs again no matter what you type in when it asks you if you want to run it again.

How would i put it in a loop and mke it run over and over and if they type no it ends the program?

All help is appreciated very much

import java.io.*;
public class Temp2
 
{
	public static void main(String[] args) throws IOException {
    	BufferedReader input= new BufferedReader(new InputStreamReader(System.in));
 
    		double prc;
    		double rcvd;
	    	int dllrs,qrtrs,dms,nckls,pnns;
	    	System.out.println("Enter Amount Recieved");
	    	rcvd=Double.parseDouble(input.readLine());
	        System.out.println("Enter Price Of Item");
	        prc=Double.parseDouble(input.readLine());
	        double chngdue=rcvd-prc;
	        System.out.println("Change Due"+" "+chngdue);
		    double lftvr;
		    dllrs=(int)chngdue/1;
		    System.out.println("Dollars:"+" "+dllrs);
		    lftvr=chngdue-dllrs;
		    qrtrs=(int)(lftvr/.25);
		    System.out.println("Quarters:"+" "+qrtrs);
		    lftvr-=(qrtrs*.25);
		    dms=(int)(lftvr/.10);
		    System.out.println("Dimes:"+" "+dms);
		    lftvr-=(dms*.10);
		    nckls=(int)(lftvr/.05);
		    System.out.println("Nickels:"+" "+nckls);
		    lftvr-=(nckls*.05);
		    pnns=(int)(lftvr/.01);
		    System.out.println("Pennies:"+" "+pnns);
		    System.out.println("Would you like to run the program again");
		    String answer="yes";
		    answer=input.readLine();
		         if (answer=="yes")
			        System.out.println("OK"); 
			    	System.out.println("Enter Amount Recieved");
			    	rcvd=Double.parseDouble(input.readLine());
			        System.out.println("Enter Price Of Item");
			        prc=Double.parseDouble(input.readLine());
			        System.out.println("Change Due"+" "+chngdue);
				    System.out.println("Dollars:"+" "+dllrs);
				    System.out.println("Quarters:"+" "+qrtrs);
				    System.out.println("Dimes:"+" "+dms);
				    System.out.println("Nickels:"+" "+nckls);
				    System.out.println("Pennies:"+" "+pnns);
		System.out.println("Would you like to run theprogram again");
				    answer=input.readLine();
 
 
 
 
 
 
 
 
 
 
		}
	}

The easiest way I've found to loop a program is to use a do while loop around the entire thing. What you have is the original program, then a duplicate inside an if statement (which by the way needs {} if you want it to do more than the first line of code beneath it). This is just unnecessary code.

Without "doing it for you", try something like this:

do {
     boolean repeat = false;
     // Code for program here
     // ...
     System.out.println("Would you like to run the program again?");
     System.out.println("Y or y for yes. Any other key for no");
     char response = input.nextLine().charAt(0);
     if ((response == 'Y') || (response == 'y'))
          repeat = true;
} while (repeat == true);

You can alter that to allow the user to input N or n for no, and also provide a catch if they enter something other than Y y N n. Hope this helps!

Do i need to import anything?

Here is the one I did.

import javax.swing.*;
 
public class katzensteinHW3 {
	public static void main( String[] args ) {
 
	//...Varibles declared for whole program.    
	int amount, originalAmount, halfDollar, quarters, dimes, nickels, pennies, selection;
	boolean runAgain = true;  
 
	  //...Loop
	  do{
 
	//...Enter the integer 1-100.
	String amountString = JOptionPane.showInputDialog(
	           "Enter a whole number from 1 to 99.\n"
	           + "I will output a combination of coins\n"
	           + "that equals that amount of change."); 	  
 
	amount = Integer.parseInt(amountString);
	originalAmount = amount;    
 
	halfDollar = amount/50;		  
	amount = amount%50;
	quarters = amount/25;
	amount = amount%25;
	dimes = amount/10;
	amount = amount%10;
	nickels = amount/5;
	amount = amount%5;
	pennies = amount;	 
 
//...Showes orginalAmount (Integer intered for amountString).
	   JOptionPane.showMessageDialog(null,
		                       originalAmount 
		+ " cents in coins can be given as:\n"
      		+ halfDollar + " half dollar\n"          
		+ quarters + " quarters\n"
		+ dimes + " dimes\n"
		+ nickels + " nickels and\n"
		+ pennies + " pennies");
 
		//...Asks if you want to run anouther.
		selection = JOptionPane.showConfirmDialog(null,
			  "Would you like to run another?","Confirmation",
									JOptionPane.YES_NO_OPTION);
 
		runAgain = (selection == JOptionPane.YES_OPTION);
 
  		 //...Continues the loop.	   
		}while (runAgain);
 
		System.exit(0); //...Ends the window.  
   }
}

It's usually best to let someone learn on their own and just guide them than give them the answer, jeremykatz.

But in response to your question, the only import you would need is for the Scanner class if you choose to use that.

So im still having problems it say "cannot find symbol" for respone or repeat

import java.io.*;
import javax.swing.*;
public class Temp2
 
{
	public static void main(String[] args) throws IOException {
    	BufferedReader input= new BufferedReader(new InputStreamReader(System.in));
	do {
 
           double prc;
    		double rcvd;
	    	int dllrs,qrtrs,dms,nckls,pnns;
	    	System.out.println("Enter Amount Recieved");
	    	rcvd=Double.parseDouble(input.readLine());
	        System.out.println("Enter Price Of Item");
	        prc=Double.parseDouble(input.readLine());
	        double chngdue=rcvd-prc;
	        System.out.println("Change Due"+" "+chngdue);
		    double lftvr;
		    dllrs=(int)chngdue/1;
		    System.out.println("Dollars:"+" "+dllrs);
		    lftvr=chngdue-dllrs;
		    qrtrs=(int)(lftvr/.25);
		    System.out.println("Quarters:"+" "+qrtrs);
		    lftvr-=(qrtrs*.25);
		    dms=(int)(lftvr/.10);
		    System.out.println("Dimes:"+" "+dms);
		    lftvr-=(dms*.10);
		    nckls=(int)(lftvr/.05);
		    System.out.println("Nickels:"+" "+nckls);
		    lftvr-=(nckls*.05);
		    pnns=(int)(lftvr/.01);
		    System.out.println("Pennies:"+" "+pnns);
		    System.out.println("Would you like to run the program again");
     System.out.println("Would you like to run the program again?");
     System.out.println("Y or y for yes. Any other key for no");
     boolean repeat= false;
     char response= input.readLine().charAt(0);
     if ((response == 'Y') || (response == 'y'))
 
          repeat= true;
} while (repeat==true);
 
 
		         if (response=='Y')
			    	System.out.println("Enter Amount Recieved");
			        double rcvd;
			    	rcvd=Double.parseDouble(input.readLine());
			        System.out.println("Enter Price Of Item");
			      	double prc;
			        prc=Double.parseDouble(input.readLine());
			    	int dllrs,qrtrs,dms,nckls,pnns;
			        double chngdue=rcvd-prc;
			        System.out.println("Change Due"+" "+chngdue);
				    double lftvr;
				    dllrs=(int)chngdue/1;
				    System.out.println("Dollars:"+" "+dllrs);
				    lftvr=chngdue-dllrs;
				    qrtrs=(int)(lftvr/.25);
				    System.out.println("Quarters:"+" "+qrtrs);
				    lftvr-=(qrtrs*.25);
				    dms=(int)(lftvr/.10);
				    System.out.println("Dimes:"+" "+dms);
				    lftvr-=(dms*.10);
				    nckls=(int)(lftvr/.05);
				    System.out.println("Nickels:"+" "+nckls);
				    lftvr-=(nckls*.05);
				    pnns=(int)(lftvr/.01);
				    System.out.println("Pennies:"+" "+pnns);
				    System.out.println("Would you like to run the program again");
		     System.out.println("Would you like to run the program again?");
		     System.out.println("Y or y for yes. Any other key for no");
 
 
 
 
 
 
 
 
 
 
		}
	}

Try defining them both right before the do while loop.

boolean repeat = false; // A value is necessary
char response

Then remove the char in front of response within the loop.

Thanks man it runs like a charm now

Originally Posted by SwEeTAcTioN

Thanks man it runs like a charm now

No problem, glad I could help!