java - Swing: Visual interface connect to second frame -


i have 2 frames. want first frame open second. tried this, leads exception.

class aboutaction implements actionlistener {         public void actionperformed(actionevent e) {             frame.dispose();             aboutinfo = new aboutinfo();             about.frame.setvisible(true);         }     } about.addactionlistener(new aboutaction());

this full program: https://github.com/zhelyazkov97/fuel-calculator.git.

you're basic problem nullpointerexception create misunderstanding of how swing works , bad design.

basically, define class as...

public class aboutinfo extends jframe {      private jpanel contentpane;     javax.swing.jframe frame;

now, here confusion starts, have 2 frames, ever add components instance of aboutinfo.

the basic answer here is, rid of frame, it's confusing issue. in fact, shouldn't extending jframe in first place, should use jpanel , add instances of class instances of jframe or jdialog or ever container want


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