java - Accessing Variable within JButton ActionListener -


this seems simple problem, i'm having lot of trouble figuring out how deal it.

sample scenario:

    final int number = 0;      jframe frame = new jframe();     frame.setvisible(true);      frame.setdefaultcloseoperation(exit_on_close);      frame.setsize(400, 400);       final jtextarea text = new jtextarea();     frame.add(text, borderlayout.north);      jbutton button = new jbutton(number + "");      button.addactionlistener(new actionlistener() {      public void actionperformed(actionevent arg0) {          number++; // error on line         text.settext(number + "");     }});     frame.add(button, borderlayout.south);

i have no idea go.

if declared number final, cannot modified value. must remove final modificator.

then, can access variable via:

public class scenario {     private int number;      public scenario() {         jbutton button = new jbutton(number + "");         button.addactionlistener(new actionlistener() {              public void actionperformed(actionevent arg0) {                  scenario.this.number++;                 text.settext(scenario.this.number + "");             }         });     } }

the notation "classname.this" allow access object of class in.

keep atention in when use "number" first time, -new jbutton(number)-, can access number directly, because in scenario scope. when use inside actionlistener, in actionlistener scope instead of scenario scope. why cannot see variable "number" directly inside of action listener , have access instance of scenario in. can done scenario.this


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