Debugging Java in Netbeans

Question

I'm a beginner in java. I'm trying to debug a simple program that returns the number of digits of an entered number. After inserting the breakpoint and starting debugging it says "No variable to display because there is no current thread"

package learning1;

import java.util.Scanner;
import java.lang.Math;
public class Learning1 {

 public static void main(String[] args) { 
     int a;
     Scanner scan = new Scanner (System.in);
     System.out.print("Enter number");
     a = scan.nextInt();
     int i=a;
     int count=0;
     while(i>1){
         i = a%10;
         count = count + 1;
     }
     System.out.print("Number of digits is " + count );
   }

}

Are you stopped at the breakpoint? That message usually means you are not stopped at a breakpoint. Is it possible the code never reached the statement on which you set the BP? — Jim Garrison, Apr 06 '18 at 05:41

score 0 · Accepted Answer · answered Apr 06 '18 at 06:50

Well, it depends where you place your breakpoint. Take your mouse pointer and click on the editor line number where the line:

public static void main(String[] args) {

is located. A light red triangle should appear over the line number:

or you can set a break-point on a line within the main() method. For example, if you click on the editor line number 12 you will see a light red square and the entire code line itself is highlighted with the same color:

Now all you need to do is select the Debug Project toolbar button or select Debug Project from the Debug menu bar to run your application in Debug mode:

When your code runs and it reaches the break point the red highlighted line will turn green and you can view your variables as then become declared and initialized within the Variables tab of the pane below the editor:

To step through your code one line at a time just hit the F8 key on your keyboard.

Debugging Java in Netbeans

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