android TabHost(选项卡)的使用方法

<?xml version="1.0" encoding="utf-8"?>

<tabhost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <linearlayout android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="fill_parent">

        <tabwidget android:id="@android:id/tabs"
            android:layout_alignparentbottom="true"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"/>

        <framelayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" />

    </linearlayout>

</tabhost>

public class mainactivity extends tabactivity {

    private tabhost my_tabhost; 
    private tabwidget my_tabwidget;
    private int i,k;
    private textview tv;

    private string[] tabmenu = { "系统", "硬件", "操作"};
    private intent intent0, intent1, intent2;
    private intent[] intents = { intent0, intent1, intent2};
    private tabhost.tabspec tabspec0, tabspec1, tabspec2, tabspec3;
    private tabhost.tabspec[] tabspecs = { tabspec0, tabspec1, tabspec2, tabspec3};

    public static context mcontext;

    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
       　　　　　　 　　// 不要窗体标题
        　　　　　　　requestwindowfeature(window.feature_no_title);
        　　　　　　 setcontentview(r.layout.activity_main);
        setcontentview(r.layout.activity_main);

        my_tabhost = gettabhost();

        intent0 = new intent(this, system.class);
        intent1 = new intent(this, hardware.class);
        intent2 = new intent(this, operation.class);

        tabspec0 = my_tabhost.newtabspec("system").setindicator(tabmenu[0],null).
                setcontent(intent0);
        tabspec1 = my_tabhost.newtabspec("hardware").setindicator(tabmenu[1],null).
                setcontent(intent1);
        tabspec2 = my_tabhost.newtabspec("operation").setindicator(tabmenu[2],null).
                setcontent(intent2);

        my_tabhost.addtab(tabspec1);
        my_tabhost.addtab(tabspec0);
        my_tabhost.addtab(tabspec2);
<br> 　　　　            // 设置默认选中的选项卡为第2个      
                     my_tabhost.setcurrenttab(1);

    }

}