Android课程---Activity 带返回值的跳转

Activity2.java

package com.hanqi.test4;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;

public class Activity2 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_2);

        //接收信息
        //获取意图

        //传递过来的Intent
       Intent intent = getIntent();

       String s = intent.getExtras().getString("myet");
       EditText mytv = (EditText)findViewById(R.id.mytv);
       mytv.setText(s);
    }
    //普通返回
    public void onclick(View v)
    {
        //关闭当前activity
        finish();
    }
    public void onclick2(View v)
    {
        //存储返回数据 也要用intent

        EditText mytv = (EditText)findViewById(R.id.mytv);
      // Log.e("TAG", "mytv =" + mytv.getText().toString());
//
       Bundle bundle = new Bundle();
       bundle.putString("mytv", mytv.getText().toString());
        //设置返回数据
        //先设置ResultCode，再设置存储数据的意图
        setResult(RESULT_OK, new Intent().putExtras(bundle));

        finish();

    }
}

activity_2.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.hanqi.test4.Activity2">

    <EditText
        android:layout_width="100dp"
        android:layout_height="wrap_content"
        android:text="测试"
        android:id="@+id/mytv"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="普通返回"
        android:onClick="onclick"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="带数据返回"
        android:onClick="onclick2"
        />

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.hanqi.test4">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity"
            android:label="@string/app_name">
            <intent-filter>      <!--//意图过滤器-->
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".Activity2"></activity>
    </application>

</manifest>

MainActivity.java

package com.hanqi.test4;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

/**
 * Created by Administrator on 2016/3/21.
 */
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main_layout);
    }

    //普通方式
    public void onClick(View v)
    {
        Log.e("Test4_TAG", "按钮的点击监听被触发");
        //静态方法
        //特点：不用实例化/直接用类名就可以调用
        //构建了Toast实例
        //方法链（一个方法后面跟另一个方法）
        Toast.makeText(this,"按钮的点击监听被触发",Toast.LENGTH_LONG).show();

//        Toast toast = Toast.makeText(this, "按钮的点击被触发", Toast.LENGTH_LONG);
//        toast.show();
        //意图 intent
        //取得要传递的信息
        //获取view实例

        EditText myet = (EditText)findViewById(R.id.myet);
        String string = myet.getText().toString();
        Intent intent = new Intent(this,Activity2.class);
        //存储内容
        //getExtra Bundle 实际是一个HashMap,进行限制
        //intent.getExtras().putString("myet",string);

        intent.putExtra("myet",string);//重载

        //启动方法不一样
        startActivity(intent);

    }

    //带返回的方式

    public void onclick2(View v)
    {
        EditText myet = (EditText)findViewById(R.id.myet);
        String string = myet.getText().toString();
        Intent intent = new Intent(this,Activity2.class);

        intent.putExtra("myet", string);

        //有返回数据的启动方式
        //第一个参数是intent
        //第二个参数是requestCode(请求码)作用：为了区分不同的请求
        startActivityForResult(intent,1);

    }

    //重写 处理返回信息的监听（也叫回调方法）
    //监听所有返回信息的
    //必须要有requestCode区分由哪个请求返回的

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Log.e("TAG","requestCode="+requestCode+"resultCode"+resultCode);

        if(requestCode ==1)
        {
           if (resultCode ==RESULT_OK)
           {
              //获取返回信息
               String string = data.getExtras().getString("mytv");
               EditText editText = (EditText)findViewById(R.id.myet);
               editText.setText(string);
               Toast.makeText(this, "返回信息 =" + string, Toast.LENGTH_LONG);
           }
            else
           {
               Toast.makeText(this,"返回信息有误",Toast.LENGTH_SHORT);
           }
        }
    }

}

main_layout.xml

<?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:orientation="vertical"
    >

    <EditText
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:id="@+id/myet"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="普通方式"
        android:onClick="onClick"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="带返回方式"
        android:onClick="onclick2"/>
</LinearLayout>