从片段访问其他片段变量或元素

Question

例如，我有 2 个片段，包括 1 个整数变量和 1 个 TextView。其中一个有一个按钮。我希望这个按钮更改所有整数和文本视图，包括其他片段。如何访问其他片段的变量和文本视图？请用示例代码进行解释。

Answer 1

片段到片段的通信基本上是通过通常托管片段的活动进行的，在片段 A 中定义一个接口，然后让您的活动实现该接口。现在，您可以在片段中调用接口方法，您的活动将收到该事件。现在在您的活动中，您可以调用第二个片段以使用接收的值更新文本视图（例如）：

// You Activity implements your interface which is defined in FragmentA
public class YourActivity implements FragmentA.TextClicked{
    @Override
    public void sendText(String text){
        // Get instance of Fragment B using FragmentManager
        FraB frag = (FragB)
            getSupportFragmentManager().findFragmentById(R.id.fragment_b);
        frag.updateText(text);
    }
}

// Fragment A defines an Interface, and calls the method when needed
public class FragA extends Fragment{
    TextClicked mCallback;
    public interface TextClicked{
        public void sendText(String text);
    }
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try {
            mCallback = (TextClicked) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                + " must implement TextClicked");
        }
    }
    public void someMethod(){
        mCallback.sendText("YOUR TEXT");
    }
    @Override
    public void onDetach() {
        mCallback = null; // => avoid leaking
        super.onDetach();
    }
}
// Fragment B has a public method to do something with the text
public class FragB extends Fragment{
    public void updateText(String text){
        // Here you have it
    }
}