startActivityForResult_在startactivityforresult方法表示请求码的参数是-优快云博客

本文介绍Android中Activity间如何传递返回值，并通过一个具体示例进行说明：用户选择城市后将结果返回到上一Activity。涉及Activity的启动方式、请求码与结果码的应用。

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在上一篇里面写了Activity之间的传值，这一篇里面写写怎么启动一个新的Activity之后，得到它的返回值

获得返回值需要重写当前Activity的onActivityResult(int requestCode,int resultCode,Intent intent),requestCode代表请求码,而resultCode代表结果码

下面是一个例子，点击按钮，弹出城市选择框，选中的城市返回显示到文本框上

界面xml如下

[html]view plaincopyprint? 
   
 <?xml version="1.0" encoding="utf-8"?>  
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
     android:layout_width="fill_parent"  
     android:layout_height="fill_parent"  
     android:orientation="vertical" >  
   
     <TableLayout  
         android:layout_width="match_parent"  
         android:layout_height="wrap_content" >  
   
         <TableRow  
             android:id="@+id/tableRow1"  
             android:layout_width="wrap_content"  
             android:layout_height="wrap_content" >  
   
             <Button  
                 android:id="@+id/bn"  
                 android:layout_width="wrap_content"  
                 android:layout_height="wrap_content"  
                 android:text="选择您所在的城市" />  
   
             <EditText  
                 android:id="@+id/city"  
                 android:layout_width="fill_parent"  
                 android:layout_height="wrap_content"  
                 android:ems="10" android:width="180dp">  
   
                 <requestFocus />  
             </EditText>  
   
         </TableRow>  
   
         <TableRow  
             android:id="@+id/tableRow2"  
             android:layout_width="wrap_content"  
             android:layout_height="wrap_content" >  
         </TableRow>  
   
         <TableRow  
             android:id="@+id/tableRow3"  
             android:layout_width="wrap_content"  
             android:layout_height="wrap_content" >  
         </TableRow>  
   
         <TableRow  
             android:id="@+id/tableRow4"  
             android:layout_width="wrap_content"  
             android:layout_height="wrap_content" >  
         </TableRow>  
     </TableLayout>  
   
 </LinearLayout>  

代码如下，重点是onActivityResult方法

[java]view plaincopyprint? 
   
 package WangLi.Activity.ActivityForResult;  
   
 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.EditText;  
   
 public class ActivityForResult extends Activity {  
     Button bn;  
     EditText city;  
     /** Called when the activity is first created. */  
     @Override  
     public void onCreate(Bundle savedInstanceState) {  
         super.onCreate(savedInstanceState);  
         setContentView(R.layout.main);  
         //获取界面上的组件  
         bn = (Button)findViewById(R.id.bn);  
         city = (EditText)findViewById(R.id.city);  
         bn.setOnClickListener(new OnClickListener(){  
             public void onClick(View source)  
             {  
                 //创建需要对应于目标Activity的Intent  
                 Intent intent = new Intent(ActivityForResult.this,SelectCityActivity.class);  
                 //启动指定Activity并等待返回结果,其中0是请求码,用于标识该请求  
                 startActivityForResult(intent,0);  
             }  
         });  
     }  
     @Override  
     public void onActivityResult(int requestCode,int resultCode,Intent intent)  
     {  
         //当requestCode,resultCode同时为0时,也就是处理特定的结果  
         if(requestCode == 0 && resultCode == 0)  
         {  
             //取出Intent里的数据  
             Bundle data = intent.getExtras();  
             //取出Bundle中的数据  
             String resultCity = data.getString("city");  
             //修改city文本框  
             city.setText(resultCity);  
         }  
     }  
 }  

点击后出现选择城市的窗口,界面全部是动态生成，没有xml文件

选中后，此窗口关闭，回到第一个窗口，显示所选的城市

选择城市代码窗口如下

[java]view plaincopyprint? 
   
 package WangLi.Activity.ActivityForResult;  
   
 import android.app.ExpandableListActivity;  
 import android.content.Intent;  
 import android.os.Bundle;  
 import android.view.Gravity;  
 import android.view.View;  
 import android.view.ViewGroup;  
 import android.widget.AbsListView;  
 import android.widget.BaseExpandableListAdapter;  
 import android.widget.ExpandableListAdapter;  
 import android.widget.ExpandableListView;  
 import android.widget.ExpandableListView.OnChildClickListener;  
 import android.widget.ImageView;  
 import android.widget.LinearLayout;  
 import android.widget.TextView;  
   
 public class SelectCityActivity extends ExpandableListActivity {  
      //定义省份数组  
      private String[] provinces = new String[]  
              {"广东","广西","湖南"};  
      private String[][] cities = new String[][]  
      {  
              {"广州","深圳","珠海","中山"},  
              {"桂林","柳州","南宁","北海"},  
              {"长沙","岳阳","衡阳","株洲"}  
      };  
        
      public void onCreate(Bundle saveInstanceState)  
      {  
          super.onCreate(saveInstanceState);  
          ExpandableListAdapter adapter = new BaseExpandableListAdapter()  
          {  
             //获取指定组位置,指定子列表项处的子列表项数据  
             public Object getChild(int groupPosition,int childPosition)  
             {  
                 return cities[groupPosition][childPosition];  
             }  
             public long getChildId(int groupPosition,int childPosition)  
             {  
                 return childPosition;  
             }  
             public int getChildrenCount(int groupPosition)  
             {  
                 return cities[groupPosition].length;  
             }  
             private TextView getTextView()  
             {  
                 AbsListView.LayoutParams lp =   
                         new AbsListView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,64);  
                 TextView textView = new TextView(SelectCityActivity.this);  
                 textView.setLayoutParams(lp);  
                 textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);  
                 textView.setPadding(36, 0, 0, 0);  
                 textView.setTextSize(20);  
                 return textView;  
             }  
             public View getChildView(int groupPosition,int childPosition,boolean isLastChild,  
                     View convertView,ViewGroup parent)  
             {  
                 TextView textView = getTextView();  
                 textView.setText(getChild(groupPosition,childPosition).toString());  
                 return textView;  
             }  
             public Object getGroup(int groupPosition)  
             {  
                 return provinces[groupPosition];  
             }  
             public int getGroupCount()  
             {  
                 return provinces.length;  
             }  
             public long getGroupId(int groupPosition)  
             {  
                 return groupPosition;  
             }  
             public View getGroupView(int groupPosition,boolean isExpanded,  
                     View convertView,ViewGroup parent)  
             {  
                 LinearLayout l1 = new LinearLayout(SelectCityActivity.this);  
                 l1.setOrientation(0);  
                 ImageView logo = new ImageView(SelectCityActivity.this);  
                 l1.addView(logo);  
                 TextView textView = getTextView();  
                 textView.setText(getGroup(groupPosition).toString());  
                 l1.addView(textView);  
                 return l1;  
             }  
             public boolean isChildSelectable(int groupPosition,int childPosition)  
             {  
                 return true;  
             }  
             public boolean hasStableIds()  
             {  
                 return true;  
             }  
          };  
             //设置窗口显示列表  
         setListAdapter(adapter);  
         getExpandableListView().setOnChildClickListener(new OnChildClickListener()  
         {  
             public boolean onChildClick(ExpandableListView parent,View source,  
                 int groupPosition,int childPosition,long id)  
             {  
                 //获取启动该Activity之前的Activity对应的Intent  
                 Intent intent = getIntent();  
                 Bundle data = new Bundle();  
                 data.putString("city", cities[groupPosition][childPosition]);  
                 intent.putExtras(data);  
                 //设置该SelectActivity的结果码,并设置结束之后退回的Activity  
                 SelectCityActivity.this.setResult(0,intent);  
                 //结束SelectActivity  
                 SelectCityActivity.this.finish();  
                 return false;  
             }  
         });  
      }  
 }  