Android中Activity跳转 startActivity和startActivityForResult之间的区别

startActivity(intent)：只是从当前活动界面跳转到另外一个界面，两个界面中不再有联系。

startActiivityForResult(requestcode,intnet):可以经当前活动界面认为是一个父窗体，要跳转的界面为子窗体，当子窗体关闭时，父窗体会执行onActivityResult()方法，并可以获取子窗体的返回值.

详细代码:

package irdc.ex03_11; /* import相关class */

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.RadioButton;

public class EX03_11 extends Activity
{
private EditText et;
private RadioButton rb1;
private RadioButton rb2;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState); /* 加载main.xml Layout */
setContentView(R.layout.main);
/*
* 以findViewById()取得Button对象，并加入onClickListener
*/
Button b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(new Button.OnClickListener()
{
public void onClick(View v)
{
/* 取得输入的身高 */
et = (EditText) findViewById(R.id.height);
double height = Double.parseDouble(et.getText().toString());

/* 取得选择的性别 */
String sex = "";
rb1 = (RadioButton) findViewById(R.id.sex1);
rb2 = (RadioButton) findViewById(R.id.sex2);

if (rb1.isChecked())
{
sex = "M";
} else
{
sex = "F";
}
/* new一个Intent对象，并指定class */
Intent intent = new Intent();
intent.setClass(EX03_11.this, EX03_11_1.class);
/*
* new一个Bundle对象，并将要传递的数据传入
*/
Bundle bundle = new Bundle();
bundle.putDouble("height", height);
bundle.putString("sex", sex);
/*
* 将Bundle对象assign给Intent
*/
intent.putExtras(bundle);
/*
* 调用Activity EX03_11_1
*/
startActivityForResult(intent, 0);
}
});
}

/*
* 重写 onActivityResult()
* 当SubActivity界面关闭时，执行该方法
*/
@Override
protected void onActivityResult(int requestCode, int resultCode,
Intent data)
{
switch (resultCode)
{
case RESULT_OK:
/*
取得数据，并显示于画面上
*/
Bundle bunde = data.getExtras();
String sex = bunde.getString("sex");
double height = bunde.getDouble("height");
et.setText("" + height);
if (sex.equals("M"))
{
rb1.setChecked(true);
} else
{
rb2.setChecked(true);
}
break;
default:
break;
}
}
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/widget0"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<TextView
android:id="@+id/title"
android:layout_width="260dp"
android:layout_height="56dp"
android:layout_x="36px"
android:layout_y="32px"
android:text="@string/title"
android:textSize="24sp" />

<TextView
android:id="@+id/text1"
android:layout_width="wrap_content"
android:layout_height="37px"
android:layout_x="18dp"
android:layout_y="201dp"
android:text="@string/text1"
android:textSize="18sp" />

<EditText
android:id="@+id/height"
android:layout_width="130px"
android:layout_height="wrap_content"
android:layout_x="81dp"
android:layout_y="188dp"
android:ems="10"
android:numeric="decimal"
android:textSize="18sp" >

<requestFocus />
</EditText>

<TextView
android:id="@+id/text2"
android:layout_width="wrap_content"
android:layout_height="29px"
android:layout_x="12dp"
android:layout_y="110dp"
android:text="@string/text2"
android:textSize="18sp" />

<TextView
android:id="@+id/text3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_x="188dp"
android:layout_y="203dp"
android:text="cm"
android:textSize="18sp" />

<RadioGroup
android:id="@+id/sex"
android:layout_width="300px"
android:layout_height="100px"
android:layout_x="80dp"
android:layout_y="97dp"
android:checkedButton="@+id/sex1"
android:orientation="horizontal" >

<RadioButton
android:id="@+id/sex1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="男的" />

<RadioButton
android:id="@+id/sex2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="女的" />
</RadioGroup>

<Button
android:id="@+id/button1"
android:layout_width="104dp"
android:layout_height="wrap_content"
android:layout_x="78dp"
android:layout_y="264dp"
android:text="計算" />

</AbsoluteLayout>

父Activity跳转到子Activity

详细代码:

package irdc.ex03_11; /* import相关class */

import java.text.DecimalFormat;
import java.text.NumberFormat;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class EX03_11_1 extends Activity
{
Bundle bunde;
Intent intent;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
/* 载入mylayout.xml Layout */
setContentView(R.layout.myalyout);
/* 取得Intent中的Bundle对象 */
intent = this.getIntent();
bunde = intent.getExtras();
/* 取得Bundle对象中的数据 */
String sex = bunde.getString("sex");
double height = bunde.getDouble("height");
/* 判断性别 */
String sexText = "";
if (sex.equals("M"))
{
sexText = "男性";
} else
{
sexText = "女性";
}
/* 取得标准体重 */
String weight = this.getWeight(sex, height);
/* 设定输出文字 */
TextView tv1 = (TextView) findViewById(R.id.text1);
tv1.setText("你是一位" + sexText + "\n你的身高是" + height + "公分\n你的标准体重是"
+ weight + "公斤");
/* 以findViewById()取得Button对象，并加入onClickListener */
Button b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(new Button.OnClickListener()
{
public void onClick(View v)
{
/* 回传result回上一个activity */
EX03_11_1.this.setResult(RESULT_OK, intent);
/* 关闭activity */
EX03_11_1.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;
}

/*
* 以findViewById()取得Button对象，并加入onClickListener
*/
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;
}
}

subLayout.xml

<?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/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp"
android:layout_x="50px"
android:layout_y="72px"
/>
<Button android:id="@+id/button1" android:layout_width="131dp" android:layout_height="wrap_content" android:layout_x="71dp" android:layout_y="134dp" android:text="回上一頁"/>
</AbsoluteLayout>