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>