<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.test24.MainActivity" >
  
	<TextView 
	    android:id="@+id/tv_result"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test24"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="21" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".SecondActivity"
            android:label="@string/title_activity_second" >
        </activity>
    </application>

</manifest>

package com.example.test24;

import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {
	private TextView result;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		//关联控件
		result=(TextView) findViewById(R.id.tv_result);
		//创建Intent对象
		Intent intent=new Intent();
		//将参数放入intent
		intent.putExtra("num1", 10);
		intent.putExtra("num2", 20);
		//跳转到指定的Activity
		intent.setClass(this, SecondActivity.class);
		//启动Activity并返回结果
		startActivityForResult(intent, 0x002);
	}
	
	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		if(requestCode==0x002&&resultCode==0x001){
			int resultData=data.getIntExtra("result", -1);
			result.setText(resultData+"");
		}
		super.onActivityResult(requestCode, resultCode, data);
	}
}

package com.example.test24;

import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class SecondActivity extends ActionBarActivity {
	private Button back;
	private int result;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_second);
		//关联控件
		back=(Button) findViewById(R.id.btn_back);
		//获取intnet传递过来的值
		Intent intent=getIntent();
		int num1=intent.getIntExtra("num1", -1);
		int num2=intent.getIntExtra("num2", -1);
		//求和
		result=sum(num1,num2);
		//点击back添加点击事件匿名内部类
		back.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				//创建Intent对象
				Intent intent=new Intent();
				//将求和的结果放进intent中
				intent.putExtra("result", result);
				//返回结果
				setResult(0x001,intent);
				//关闭当前界面
				finish();
			}
		});
	}
	
	/*求和*/
	public int sum(int num1,int num2){
		return num1+num2;
	}
}