Question

here is my snippet.It returns a null pointer exception..jlabel1 is already set and working

JLabel j[]=new JLabel[10];
i=0;    
j[i]=new JLabel();
j[i].setText("1");
this.add(j[i]);

Edit (from the comments)

JLabel j[]=new JLabel[50]; 
try { 
  Rectangle bounds = jLabel1.getBounds(); 
  j[i].setText("1"); 
  this.add(j[i]); 
  j[i].setBounds(jLabel1.getX(),jLabel1.getY()+50 ,jLabel1.getHeight(),jLabel1.getWidth()); } catch(Exception e) { 
  System.out.println(e.toString()); 
} 

Answer 1

The problem is that you forgot the

j[i] = new JLabel();

in the snippet you posted in the comments (although it was included in your question).

A NullPointerException is typically easy to debug as you just have to follow the stack trace to discover what exactly is null. When in doubt, you just place a breakpoint on that line and use a debugger.

To obtain the stacktrace, you can use e.printStackTrace() or simply remove the try catch block (as it is bad practice to simply have a try catch block for all exceptions)