从activity Android调用fragment方法

public interface MyFragmentInterface {
    void onFragmentMethod();
}

public class MainActivity extends AppCompatActivity implements MyFragmentInterface {

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

        // 获取fragment实例
        MyFragment myFragment = (MyFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_container);
        // 设置activity为接口的实现类
        myFragment.setMyFragmentInterface(this);
    }

    @Override
    public void onFragmentMethod() {
        // 在activity中调用fragment方法
        // TODO: 实现具体逻辑
    }
}

public class MyFragment extends Fragment {

    private MyFragmentInterface myFragmentInterface;

    public void setMyFragmentInterface(MyFragmentInterface myFragmentInterface) {
        this.myFragmentInterface = myFragmentInterface;
    }

    // 调用接口方法
    private void callInterfaceMethod() {
        if (myFragmentInterface != null) {
            myFragmentInterface.onFragmentMethod();
        }
    }
}