怎么在Android应用中实现一个选项卡功能

package lianxi;
import com.example.jichu_lianxi.R;
import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.TabHost;
public class TobHost_lianxi extends TabActivity{
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    //获取当前Activity的标签，该方法的实现已经执行了setContentView(com.android.internal.R.layout.tab_content);
    Resources resources = getResources();
    TabHost tabHost = getTabHost();
    TabHost.TabSpec spec;
    /*
     * 对方法的解释：
     * 1.   newTabSpec("artist")创建一个标签项，其中artist为它的标签标识符
     * 2.   setIndicator("标签1", resources.getDrawable(R.drawable.bulb_off))
     *      显示文本以及标签上的图标(该图标不是一个图片，而是一个xml文件)
     */
    //添加第一个标签
    Intent intent = new Intent(TobHost_lianxi.this,KeyOnclick.class);
    spec = tabHost.newTabSpec("keyonclick").setIndicator("标签1", resources.getDrawable(R.drawable.bulb_off)).setContent(intent);
    tabHost.addTab(spec);//将标签添加到标签项中
    //添加第二个标签
    Intent intent2 = new Intent(TobHost_lianxi.this,List_lianxi.class);
    spec = tabHost.newTabSpec("list").setIndicator("标签2",resources.getDrawable(R.drawable.bulb_off)).setContent(intent2);
    tabHost.addTab(spec);
    //添加第三个标签
    Intent intent3 = new Intent(TobHost_lianxi.this,ToggleButton_lianxi.class);
    spec = tabHost.newTabSpec("togglebutton").setIndicator("标签3",resources.getDrawable(R.drawable.bulb_off)).setContent(intent3);
    tabHost.addTab(spec);
    //添加第四个标签
    Intent intent4 = new Intent(TobHost_lianxi.this,ToggleButton_lianxi.class);
    spec = tabHost.newTabSpec("toggle").setIndicator("标签4",resources.getDrawable(R.drawable.bulb_off)).setContent(intent4);
    tabHost.addTab(spec);
    //设置第一次打开的默认显示的标签,参数与 .newTabSpec的参数匹配
    //tabHost.setCurrentTabByTag("toggle");
    //设置第一次打开的默认显示的标签,参数代表其添加到标签中的顺序,位置从0开始
    tabHost.setCurrentTab(1);
  }
}

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity android:name="lianxi.Mainactivity">
      <intent-filter
        >
        <action android:name="android.intent.action.MAIN"/>
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <activity android:name="lianxi.NewActivity"></activity>
    <activity android:name="lianxi.AlertDialog_lianxi"></activity>
    <activity android:name="lianxi.Notification_lianxi"></activity>
    <activity android:name="lianxi.KeyOnclick"></activity>
    <activity android:name="lianxi.List_lianxi"></activity>
    <activity android:name="lianxi.ToggleButton_lianxi"></activity>
    <activity android:name="lianxi.TobHost_lianxi"></activity>
</application>