android中的fragment是运行在activity中的，其生命周期是依赖activity的，他可以被重用，使平板电脑的大空间得以合理利用，下面给个小例子。
首先是主activity
[java]
package com.example.fragmenttest;

import android.os.Bundle;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.view.View;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);
}

public void selectFrag(View view) {
Fragment fr;

if(view == findViewById(R.id.button2)) {
fr = new FragmentTwo();

}else {
fr = new FragmentOne();
}

FragmentManager fm = getFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.fragment_place, fr);
fragmentTransaction.commit();

}

}
[/java]
主布局文件
[xml]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Fragment No.1"
android:onClick="selectFrag" />

<Button
android:id="@+id/button2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="selectFrag"
android:text="Fragment No.2" />

<fragment
android:name="com.example.fragmenttest.FragmentOne"
android:id="@+id/fragment_place"
android:layout_width="match_parent"
android:layout_height="match_parent" />

</LinearLayout>
[/xml]
本实例中有两个fragment，第一个的class文件
[java]
/**
*
*/
package com.example.fragmenttest;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
* @author 学平
*
*/
public class FragmentOne extends Fragment {

@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
// return super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_one, container, false);
}

@Override
public void onPause() {
// TODO Auto-generated method stub
super.onPause();
}

}
[/java]
第二个fragment的class文件
[java]
/**
*
*/
package com.example.fragmenttest;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
* @author 学平
*
*/
public class FragmentTwo extends Fragment {

@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
// return super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_two, container, false);
}

@Override
public void onPause() {
// TODO Auto-generated method stub
super.onPause();
}

}
[/java]
两个fragment的layout的布局文件,fragment_one.xml
[xml]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#00ffff">

<TextView
android:id="@+id/textView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="This is fragment No.1"
android:textStyle="bold" />

</LinearLayout>
[/xml]
fragment_two.xml
[xml]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ffff00">

<TextView
android:id="@+id/textView2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="This is fragment No.2"
android:textStyle="bold" />

</LinearLayout>
[/xml]

源码的下载路径 http://pan.baidu.com/s/1i381fSh