Accessing the containing class of an inner class i

问题:

This is what I'm doing now. Is there a better way to access the super class?

public class SearchWidget {
    private void addWishlistButton() {
        final SearchWidget thisWidget = this;
        button.addClickHandler(new ClickHandler() {
            public void onClick(ClickEvent event) {
                // A better way to access the super class?
                // something like "this.super" ...?
                workWithWidget(thisWidget);
            }
        }
    }
}

I'm programming with Google Web Toolkit, but I think this is really a generic Java question.

回答1:

You can use what is called the qualified this.

JLS 15.8.4. Qualified This

Any lexically enclosing instance can be referred to by explicitly qualifying the keyword this.

Let C be the class denoted by ClassName. Let n be an integer such that C is the n-th lexically enclosing class of the class in which the qualified this expression appears. The value of an expression of the form ClassName.this is the n-th lexically enclosing instance of this (§8.1.3). The type of the expression is C. It is a compile-time error if the current class is not an inner class of class C or C itself.

In this case, you can do what Martijn suggests, and use:

workWithWidget(SearchWidget.this);

References

• JLS 15.8.4. Qualified This
• JLS 8.1.3 Inner Classes and Enclosing Instances

Related questions

• Access outer class from inner class: Why is it done this way?

回答2:

You can write the name of the outer class and then .this. So:

workWithWidget(SearchWidget.this);

回答3:

To access super of the object that contains an object of an anonymous class from that object, try, in your case SearchWidget.super

---

Example:(see the third call Child.super.print())

public class Test1 {
public static void main(String[] args) {
    new Child().doOperation();
}
}

class Parent {
protected void print() {
    System.out.println("parent");
}
}

class Child extends Parent {
@Override
protected void print() {
    super.print();
    System.out.println("child");
}

void doOperation() {
    new Runnable() {
        public void run() {
            print();              // prints parent child
            Child.this.print();   // prints parent child
            Child.super.print();  // prints parent
        }
    }.run();

}
}