Java继承：第2个实例调用第1个实例方法

Question

I have a very strange problem with a java class in my android application.

I have some sub classes which extend my abstract class GameDialog

GameDialog class

public abstract class GameDialog extends Sprite
{
    private static boolean gd_visible = false;

    protected GameDialog(GameScene scene, Camera camera, VertexBufferObjectManager pSpriteVertexBufferObject){
        ...
    }

    public boolean display(){
        if(!GameDialog.gd_visible) {
            ...
        }
    }

    protected boolean hide(){
        if(GameDialog.gd_visible){
            ...
        }
    }
}

PauseDialog class

public class PauseDialog extends GameDialog {

    public PauseDialog(GameScene scene, Camera camera, VertexBufferObjectManager pSpriteVertexBufferObject) {
        super(scene, camera, pSpriteVertexBufferObject);
        ...
        final ButtonSprite play_button = new ButtonSprite(...);
        play_button.setOnClickListener(setPlayButtonListener());
    }


    private OnClickListener setPlayButtonListener() {
        return new OnClickListener() {

            @Override
            public void onClick(ButtonSprite pButtonSprite, float pTouchAreaLocalX, float pTouchAreaLocalY) {
                hide();
            }
        };
    }
}

Each time I want to display a dialog, I write this line : new PauseDialog(GameScene.this, camera, vbom).display();

The first time, it works well : the dialog is displayed, user make a choice and it's hidden. But the 2nd time, the dialog is not hidden (after user's choice).

I used the debugger to see what's going on, and the conclusion is :

• In the 2nd instance, it calls the hide() method of the first instance !

If some one can explain me what it is doing that ... Thank you.

Answer 1

It is because gd_visible is static . Delete the static keyword and it should work. Static fields doesn't belong to the instances but they belong to the class.