Activity调用 Fragment

• 1 直接调用

//findFragmentById 或者 findFragmentByTag
if (getSupportFragmentManager().findFragmentById(R.id.a_fragment)  instanceof  AFragment ){
AFragment aFragment = (AFragment ) getSupportFragmentManager().findFragmentById(R.id.a_fragment);
aFragment.doSomeThing();
}

• 2 广播发送监听
• 3 EventBus消息总线发送监听
• 4 单例模式处理

Fragment 调用 Activity

• 1 直接调用

if (getActivity() instanceof MainActivity){
MainActivity mainActivity=(MainActivity) getActivity();
mainActivity.doSomeThing();  
}

• 2 接口调用
  Fragment 中定义一个接口

  private OnFragmentInteractionListener mListener;
  public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
  }
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }
//某操作 执行这个方法
public void doSomeThing{
if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
}

Activity 实现这个接口

public class MainActivity extends AppCompatActivity implements  BlankFragment.OnFragmentInteractionListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public void onFragmentInteraction(Uri uri) {
        //todo
    }
}

• 3 广播发送监听
• 4 EventBus消息总线发送监听
• 5 单例模式处理