Android：手把手教你 实现Activity 与 Fragment 相互通信

//
MainActivity 

package com.bawei.com.haha;

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

public class MainActivity extends AppCompatActivity {
    TextView text;
    private FrameLayout fragment_container;
    private EditText ed;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //取id
        text = (TextView) findViewById(R.id.text);


        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();

        // 步骤2：获取FragmentTransaction
        final FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();

        // 步骤3：创建需要添加的Fragment
        final mFragment mfragment = new mFragment();

        // 步骤4:创建Bundle对象
        // 作用:存储数据，并传递到Fragment中
        final Bundle bundle = new Bundle();


        // 步骤5:往bundle中添加数据
        bundle.putString("message", "dsadasdas");
        // 步骤6:把数据设置到Fragment中
        mfragment.setArguments(bundle);
        // 步骤7：动态添加fragment
        // 即将创建的fragment添加到Activity布局文件中定义的占位符中（FrameLayout）
        fragmentTransaction.add(R.id.fragment_container, mfragment);
        fragmentTransaction.commit();

        //接口传值
        mfragment.sendMessage(new mFragment.ICallBack() {
            @Override
            public void huida(String daan) {
                //在点击framgae给Activity传值
                text.setText(daan);
            }
        });

    }

}

//Fragment

package com.bawei.com.haha;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

/**
 * Created by lenovo on 2018/4/9.
 */

public class mFragment extends Fragment {
    Button button;
    TextView text;
    Bundle bundle;
    String message;
    ICallBack huida;
    int i = 0;
    private EditText ed;
    private String edString;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View contentView = inflater.inflate(R.layout.fragment, container, false);
        // 设置布局文件
        button = (Button) contentView.findViewById(R.id.button);
        text = (TextView) contentView.findViewById(R.id.text);
        // 步骤1:通过getArgments()获取从Activity传过来的全部值
        bundle = this.getArguments();

        // 步骤2:获取某一值
        message = bundle.getString("message");
        //加载控件
        initView(contentView);

        // 步骤3:设置按钮,将设置的值显示出来
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                if (i == 0) {
                    // 显示传递过来的值
                    text.setText(message);
                    i++;
                } else {
                    submit();
                    //给接空赋值
                    huida.huida(edString);
                    i = 0;
                }
            }
        });

        return contentView;
    }

    private void initView(View contentView) {
        ed = (EditText) contentView.findViewById(R.id.ed);

    }

    private void submit() {
        // validate
        edString = ed.getText().toString().trim();
        if (TextUtils.isEmpty(edString)) {
            Toast.makeText(getContext(), "edString不能为空", Toast.LENGTH_SHORT).show();
            return;
        }

        // TODO validate success, do something


    }

    //定义接口给Acyiivty传值
    public interface ICallBack {
        void huida(String daan);
    }

    // 设置 接口回调 方法
    //提供外部使用的方法
    public void sendMessage(ICallBack huida) {
        this.huida = huida;
    }
}

//main布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.bawei.com.haha.MainActivity">

   <TextView
       android:id="@+id/text"
       android:layout_gravity="center"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textSize="20dp"
       android:text="我是Activity" />

   <FrameLayout
       android:layout_below="@+id/button"
       android:id="@+id/fragment_container"
       android:layout_width="match_parent"
       android:layout_height="500dp"/>




</LinearLayout>

//子布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ff0"
    android:orientation="vertical">

    <EditText
        android:id="@+id/ed"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/fragment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="我是fragment"
        android:textSize="30dp" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="等待Activity发送消息"
        android:textSize="20dp" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:text="点击接收Activity消息"
        android:textSize="20dp" />


</LinearLayout>