android studio tabhost基础 多功能时钟app tabhost

新建项目，在layout中添加tabhost组件：

xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.example.jowang.clock.MainActivity">


    <TabHost
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tabHost"
        android:layout_gravity="center_horizontal">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <TabWidget
                android:id="@android:id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">TabWidget>

            <FrameLayout
                android:id="@android:id/tabcontent"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <LinearLayout
                    android:id="@+id/tabTime"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:orientation="vertical">LinearLayout>

                <LinearLayout
                    android:id="@+id/tabAlarm"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:orientation="vertical">LinearLayout>

                <LinearLayout
                    android:id="@+id/tabTimer"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:orientation="vertical">LinearLayout>
                <LinearLayout
                    android:id="@+id/tabStopwatch"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:orientation="vertical">LinearLayout>
            FrameLayout>
        LinearLayout>
    TabHost>
LinearLayout>

在mainactivity中写入代码：

public class MainActivity extends AppCompatActivity {
    private TabHost tabHost;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tabHost=(TabHost)findViewById(R.id.tabHost);
        tabHost.setup();
        tabHost.addTab(tabHost.newTabSpec("tabTime").setIndicator("时钟").setContent(R.id.tabTime));
        tabHost.addTab(tabHost.newTabSpec("tabAlarm").setIndicator("闹钟").setContent(R.id.tabAlarm));
        tabHost.addTab(tabHost.newTabSpec("tabTimer").setIndicator("计时器").setContent(R.id.tabTimer));
        tabHost.addTab(tabHost.newTabSpec("tabStopwatch").setIndicator("秒表").setContent(R.id.tabStopwatch));

    }
}