Android中Fragment通过接口回调传递数据到Activity中

MainActivity

package com.example.zhangyu.myapplication;

import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements BlankFragment2.OnFragmentInteractionListener {

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

        //1.创建Fragment的管理对象
        FragmentManager fragmentManager = getSupportFragmentManager();
        //2.获取Fragment的事务对象并且开启事务
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        //3.调用事务中动态操作fragment的方法执行 add(添加到哪里，需要添加的fragment对象);
        fragmentTransaction.add(R.id.fl_fragment, BlankFragment2.newInstance("参数1：hello1", "参数2：hello2"));
        //4.提交事务
        fragmentTransaction.commit();

    }

    @Override
    public void onFragmentInteraction(String s) {
        TextView tvMain =  findViewById(R.id.tv_main);
        tvMain.setText(s);
    }
}

BlankFragment2

package com.example.zhangyu.myapplication;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link BlankFragment2#newInstance} factory method to
 * create an instance of this fragment.
 */
public class BlankFragment2 extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;
    private TextView tvTest2;

    public BlankFragment2() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment BlankFragment2.
     */
    // TODO: Rename and change types and number of parameters
    public static BlankFragment2 newInstance(String param1, String param2) {
        BlankFragment2 fragment = new BlankFragment2();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_blank_fragment2, container, false);
        tvTest2 = view.findViewById(R.id.tv_test2);
        tvTest2.append("\n" + mParam1);
        tvTest2.append("\n" + mParam2);
        tvTest2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onButtonPressed();
            }
        });
        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed() {
        if (mListener != null) {
            mListener.onFragmentInteraction("接口回调，Fragment传递数据到Activity");
        }
    }

    @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;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * 

     * See the Android Training lesson Communicating with Other Fragments for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(String s);
    }
}