Android中返回数据到前一个Activity — startActivityForResult方法

本文讲述了Android中返回数据到前一个Activity — startActivityForResult方法。

实现步骤：

第一步：建立Android 工程：ActivityDemo。

                                                                   

第二步：编写Activity 的子类别：ActivityDemo，其程序代码如下：

package com.a3gs.activity;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
 
public class ActivityDemo extends Activity {
    private RadioGroup rg;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        Button btn = (Button) findViewById(R.id.btn);
        btn.setOnClickListener(new Button.OnClickListener(){
           @Override
           public void onClick(View v) {
              // TODO Auto-generated method stub
              EditText et = (EditText) findViewById(R.id.height);
              // 判断身高如果为空，则不提交
              if(et.getText().toString().equals("")) return;
              double height = Double.parseDouble(et.getText().toString());
              String sex = "";
              rg = (RadioGroup) findViewById(R.id.sex);
              if(rg.getCheckedRadioButtonId() == R.id.M) {
                  sex = "M";
              }
              if(rg.getCheckedRadioButtonId() == R.id.F) {
                  sex = "F";
              }
              // 用Bundle来绑定所要的数据
              Bundle bd = new Bundle();
              bd.putDouble("height", height);
              bd.putString("sex", sex);
             
              // 创建一个新的Intent，并将Bundle传进去
              Intent it = new Intent();
              it.putExtras(bd);
              it.setClass(ActivityDemo.this, Bundle2.class);
              startActivityForResult(it, RESULT_OK);
           }
        });
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
       // TODO Auto-generated method stub
       switch (resultCode) {
       case RESULT_OK:
           String sex = data.getStringExtra("sex");
           if(sex.equals("M")){
              rg.check(R.id.M);
           }else
              rg.check(R.id.F);
           break;
       default:
           break;
       }
    }
}

第三步：新建一个Activity 的子类别：Bundle2，其程序代码如下：

package com.a3gs.activity;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
 
public class Bundle2 extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.myalyout);
       
        Bundle bundle = getIntent().getExtras();
        String sex = bundle.getString("sex");
        Double height = bundle.getDouble("height");
        String weight = this.getWeight(sex, height);
        String sexStr = "";
        if(sex.equals("M")){
        sexStr = "男性";
        }else
        sexStr = "女性";
        String result = "您是一位" + sexStr +
                    "\n您的身高为：" + height + "cm" +
                    "\n您的标准体重为：" + weight +"千克";
        TextView tv = (TextView) findViewById(R.id.tv);
        tv.setText(result);
        Button backBtn = (Button) findViewById(R.id.back);
        backBtn.setOnClickListener(new Button.OnClickListener(){
           @Override
           public void onClick(View v) {
              // TODO Auto-generated method stub
              Bundle2.this.setResult(RESULT_OK, getIntent());
              Bundle2.this.finish();
           }
        });
    }
, ,
    /* 四舍五入的method */
    private String format(double num)
    {
      NumberFormat formatter = new DecimalFormat("0.00");
      String s=formatter.format(num);
      return s;
    }
    /* 计算标准体重 */ 
    private String getWeight(String sex,double height)
    {
      String weight="";
      if(sex.equals("M"))
      {
        weight=format((height-80)*0.7);
      }
      else
      {
        weight=format((height-70)*0.6);
      } 
      return weight;
    }
}

第四步：修改res/layout/main.xml，其代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_horizontal"
    >
<TextView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/title"
    android:gravity="center_horizontal"
    android:textSize="25px"
    />
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:gravity="center_vertical|center_horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    >
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/myText"
        android:gravity="center_horizontal"
        android:textSize="20px"
    />
    <RadioGroup
    android:id="@+id/sex"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:gravity="center_horizontal"
    android:textSize="20px"
    >
    <RadioButton
        android:id="@+id/M"
        android:checked="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="男"
        >
    </RadioButton>
    <RadioButton
        android:id="@+id/F"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="女"
        >
    </RadioButton>
    </RadioGroup>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:gravity="center_vertical|center_horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    >
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/myText1"
        android:gravity="center_horizontal"
        android:textSize="20px"
    />
    <EditText
       android:id="@+id/height"
       android:layout_width="80px"
    android:layout_height="wrap_content"
    android:text=""
    android:numeric="decimal"
    android:textSize="20px"
       />
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/myText2"
        android:gravity="center_horizontal"
        android:textSize="20px"
    />
</LinearLayout>
<Button
    android:id="@+id/btn"
    android:layout_width="130px"
    android:layout_height="wrap_content"
    android:text="@string/btnText"
    android:gravity="center_horizontal|center_vertical"
    android:textSize="20px"
    />
</LinearLayout>

第五步：修改res/layout/mylayout.xml，其代码如下：

<?xml version="1.0" encoding="utf-8"?>
  <AbsoluteLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
  >
    <TextView
      android:id="@+id/tv"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textSize="20sp"
      android:layout_x="50px"
      android:layout_y="72px"
    >
    </TextView>
    <Button
    android:id="@+id/back"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textSize="20sp"
       android:layout_x="80px"
       android:layout_y="152px"
       android:text="@string/backText"
    />
 </AbsoluteLayout>

第六步：修改AndroidManifest.xml，其内容如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.a3gs.activity"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ActivityDemo"
                  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=".Bundle2"/>
    </application>
    <uses-sdk android:minSdkVersion="3" />
</manifest>

出处：http://ebaina.com/html/hottech/mobile/201001/25-875.html