如何在ActionListener的actionPerformed内部传递循环索引

Question

I was wondering if there is a way to assign click event using a loop. Quick example of what I looking for: Where each button will do actions inside myMethod(int) .

So button[2] should do myMethod(2) and so on.

// imports...    
public class MyClass {

        private JButton[] buttons = new JButton[10];

        public MyClass() {
            // constructor

            for ( int i = 0; i < this.buttons.length; i++ ) {
             this.buttons[i].addActionListener( new ActionListener() {
                    public void actionPerformed( ActionEvent e ) {                  
                        MyClass.this.myMethod(i);
                    }
                });
            }
        }

        public void myMethod( int id ) {
            // perform actions
            //...
        }



    }

The code above throws error that the variable must be final or effecively final. I know why, but how can I do similiar thing?

Answer 1

Just create temporary final variable and assign i value to it. Now you can use the final variable to pass it to myMethod , like below:

// imports...    
public class MyClass {

    private JButton[] buttons = new JButton[10];

    public MyClass() {
        // constructor

        for (int i = 0; i < this.buttons.length; i++) {
            final int myFinalIndex = i;
            this.buttons[i].addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    MyClass.this.myMethod(myFinalIndex);
                }
            });
        }
    }

    public void myMethod(int id) {
        // perform actions
        // ...
    }

}