对接口感到困惑。 如何在一个类中调用接口方法并在另一个类中定义接口方法？

问题描述

I'm new to interfaces and I'm trying to do the following. 我是界面的新手，我正在尝试执行以下操作。 What am I missing? 我想念什么？

public class MyAdapter implements ItemManager.DoThisInterface {
    ...
    @Override
    doThis() {
        // Do things specific to my adapter. Define action hre.
    }
}

The interface is defined in the Item Manager, which does not know what needs to be done. 该接口在“项目管理器”中定义，该管理器不知道需要做什么。 The adapter should define the actions. 适配器应定义操作。

public class ItemManager {
    ....
    private void onCertainEvent() {
        doThis(); // do whatever is overriden in adapter. 
                  // this is kind of a placeholder for what i expect to be defined
                  // in the adapter.
                  // (this fails to compile because it can't call straight to the interface method)
    }

    // interface declaration
    public interface DoThisInterface {
        doThis();
    }
}

You should set a DoThisInterface instance on the class ItemManager , and save it in the instance field, then use the instance to call the interface method, like this 你应该设置一个DoThisInterface的类实例ItemManager ，并将其保存在实例字段，然后使用该实例调用接口方法，这样

public class ItemManager {

    private DoThisInterface mDoThisInterface;
    ....
    private void onCertainEvent() {
        if(mDoThisInterface != null){
            mDoThisInterface.doThis();
        } 
    }

    public void setDoThisInterface(DoThisInterface doThisInterface){
        mDoThisInterface = doThisInterface;
    }

    // interface declaration
    public interface DoThisInterface {
        doThis();
    }
}