How can I access a variable in an inner class without being final in java?

Question

I am trying to access in an inner class (actionListener) a variable that changes value in the main class. I can't make it final, because it changes values before the actionListener triggered.

Have anyone met the same problem?

Thank you

public class MyClass{
    private int counter = 0;

    public void myMethod(){
        //read from file
        //counter = number of lines of the file read

        JButton button = new JButton ("My button");

        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("lines = " +counter);
            }
        });
    }
}

FYI, for future reference, please edit your question, and post code in the question, not comments. Very hard to read. Thanks. — OldProgrammer, Oct 20 '14 at 00:54
Your posted code does not have the problem you've described precisely because counter is an instance field and **not** a local variable. Let me reiterate, what problems are you having with your posted code? It works. Please clarify. — Hovercraft Full Of Eels, Oct 20 '14 at 00:55
Check out [this](http://stackoverflow.com/a/12206542/2517719) answer. — Floegipoky, Oct 20 '14 at 01:16

score 1 · Answer 1 · answered Oct 20 '14 at 00:50

1

Make the variable non-local, an instance field, and then your problem is solved.

answered Oct 20 '14 at 00:50

Hovercraft Full Of Eels

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score 0 · Answer 2 · answered Oct 20 '14 at 00:41

0

You can simply pass that variable to your inner class:

public class Outer {

    private E outerValue;

    public void someMethod() {
        Inner inner = new Inner(outerValue);
        // later
        outerValue = newValue;
    }

    public class Inner {
        private final E innerValue;
        public Inner(E value) {
            this.innerValue = value;
        }
        // + other methods
    }
}

answered Oct 20 '14 at 00:41

Jean Logeart

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I think he meant anonymous class – Muli Yulzary Oct 20 '14 at 00:57

How can I access a variable in an inner class without being final in java?

2 Answers2