Java 从内部匿名类引用匿名类的外部实例
在以下代码段中:Java 从内部匿名类引用匿名类的外部实例,java,anonymous-inner-class,Java,Anonymous Inner Class,在以下代码段中: public void main(){ //Enclosing scope final TextField field = new TextField("", uiSkin) { @Override protected InputListener createInputListener() { return new TextFieldClickListener() { @Ov
public void main(){
//Enclosing scope
final TextField field = new TextField("", uiSkin) {
@Override
protected InputListener createInputListener() {
return new TextFieldClickListener() {
@Override
public boolean keyUp(com.badlogic.gdx.scenes.scene2d.InputEvent event, int keycode) {
// error1 => The local variable field may not have been initialized
System.out.println("Field "+field+"event="+event+" key={}"+keycode);
// error2 => No enclosing instance of the type TextField is accessible in scope
System.out.println("Field "+TextField.this+"event="+event+" key={}"+keycode);
return super.keyUp(event, keycode);
};
};
}
};
}
有没有办法从内部匿名类引用匿名类的外部实例
第二个错误是我在这里找到的解决方案。问题似乎有一些共同的概念和问题空间,但性质不同。可以通过定义一个新字段来解决问题,该字段捕获对封闭this的引用
//Enclosing scope
final TextField field = new TextField("", uiSkin) {
TextField this2 = this;
@Override
protected InputListener createInputListener() {
return new TextFieldClickListener() {
@Override
public boolean keyUp(com.badlogic.gdx.scenes.scene2d.InputEvent event, int keycode) {
System.out.println("Field "+this2+"event="+event+" key={}"+keycode);
return super.keyUp(event, keycode);
};
};
}
};
这个问题可以通过定义一个新字段来解决,该字段捕获对封闭的this的引用
//Enclosing scope
final TextField field = new TextField("", uiSkin) {
TextField this2 = this;
@Override
protected InputListener createInputListener() {
return new TextFieldClickListener() {
@Override
public boolean keyUp(com.badlogic.gdx.scenes.scene2d.InputEvent event, int keycode) {
System.out.println("Field "+this2+"event="+event+" key={}"+keycode);
return super.keyUp(event, keycode);
};
};
}
};