通过 Fragments 传递数据

Question

我的应用很简单，只是我有一个 FragmentA 和 FragmentB 第一个按钮通过第二个片段传递字符串数据（“Hi i'm A”）有文字显示此消息我的问题是

为什么我的“ModifyTxt”方法不起作用？

public class newFragmentA extends Fragment{
    Button button;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.newfragmenta_layout,container,false);
    }

    newFragmentB newfragmentB;
    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        button = getActivity().findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                newfragmentB.ModifyTxT("Hi I'm A");
            }
        });


       }
}

这是我的第二个 Fragment(FragmentB)

public class newFragmentB extends Fragment {
    TextView textView;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {

        return inflater.inflate(R.layout.newfragmentb_layout,container,false);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        textView = getActivity().findViewById(R.id.TV);
    }
    public void ModifyTxT(String string){
        textView.setText(string); }
}

Answer 1

试试这个：

public class FragmentB extends Fragment {
  // ...

  public static FragmentB newInstance() {
        return new FragmentB();
    }
}

在片段A中：

button.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
    FragmentB newFragment = FragmentB.newInstance();
    newFragment.modifyTxT("Hi I'm A");
  }
});

注意编码规则：类名首字母大写，方法首字母小写...

Answer 2

更喜欢使用接口与Fragments通信

public class FragmentA extends Fragment{
    public interface MyCallback{
        void modifyTxT(String text); // method naming convention start with small letter.
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        button = getActivity().findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (newfragmentB instanceof MyCallback) {
                    ((MyCallback)newfragmentB).modifyTxT("Hi I'm A");
                }
            }
        });


    }

}

public  class FragmentB extends Fragment implements FragmentA.MyCallback{

    public static FragmentB getInstance(){
        return new FragmentB();

    }

    @Override
    public void modifyTxT() {

    }
}