基于startActivityForResult方法处理两个Activity之间数据传递问题

package com.example.testactivityresquest;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.Toast;
 public class MainActivity extends Activity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);
     Button btn = (Button) findViewById(R.id.button);
     btn.setOnClickListener(new OnClickListener() {
       @Override
       public void onClick(View v) {
 
         Intent intent = new Intent(MainActivity.this, Activityb.class);
         int[] nums = { , };
         intent.putExtra(Changliang.KEY, nums);
         //有别于startActivity，如果启动的其他Activity多了以后。相当于定一个特定KEY值，返回根据KEY值返回。
         startActivityForResult(intent, Changliang.requestCode);
 
       }
     });
   }
  //Activityb传回来的数据在这个方法中获取
   @Override
   protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     int s = data.getIntExtra(Changliang.Activity_b_KEY, );
 
     Toast.makeText(getApplicationContext(), "传递两个数得到的和是：" + s, ).show();
 
   }
 }
 package com.example.testactivityresquest;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.Toast;
 public class Activityb extends Activity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activityb);
     Intent intent = this.getIntent();
     int[] n = intent.getIntArrayExtra(Changliang.KEY);
     final int nums = n[] + n[];
     Toast.makeText(this, n[] + " " + n[], ).show();
     Button btn = (Button) findViewById(R.id.button);
     btn.setOnClickListener(new OnClickListener() {
       @Override
       public void onClick(View v) {
         Intent intent = new Intent(Activityb.this, MainActivity.class);
         intent.putExtra(Changliang.Activity_b_KEY, nums);
         // 将数据根据特定键值的意图事件导入
         Activityb.this.setResult(Changliang.requestCode, intent);
         //关闭后返回主Activity
         Activityb.this.finish();
       }
     });
   }
 }
package com.example.testactivityresquest;
public class Changliang {
public static final String KEY="key";
public static final String Activity_b_KEY="key1";
public static final int requestCode=1987;
}

 <RelativeLayout 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:background="#ff" >
   <Button
     android:id="@+id/button"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_alignParentTop="true"
     android:layout_centerHorizontal="true"
     android:layout_marginTop="dp"
     android:text="启动Activityb" />
 </RelativeLayout>
 <?xml version="." encoding="utf-"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:background="#ff"
   android:orientation="vertical" >
   <Button
     android:id="@+id/button"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="返回Activity" />
 </LinearLayout>