Android ViewFlipper within TabHost for Tabs with different Views ... and better memory footprint-优快云博客

本文介绍了如何通过使用View替换Activity来优化TabHost的内存消耗和层级结构，实现更简洁高效的界面展示。通过实现OnClickListener处理点击事件，减少活动数量并优化用户交互体验。

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This article is a follow up of Use Android ActivityGroup within TabHost to show different Activity. As you probably noticed or read in the comments, the provided solution in the last article was less than ideal. Even though it does work, it uses multiple activies and therefor has a bigger memory consumption than necessary.

What happens when you use ActivityGroup with Tabhost

In the previous example we had one Activiy per tab. One tab was even holding two Activies and using ActivityGroup to switch between them. That's a total of five Activites that end up on the activity stack. Also the hierarchy was more nested than needed.

The improvement

So instead of using a Activity per Tab we can display a View in each. Thus we only need one Activity, all the events are caught by the class, so you need to find an ordered way of catching them. My example will implement the OnClickListener.

To keep the example short, we have two tabs. In the first one, there's a ViewFlipper which switches between two TextViews when clicked. In the second tab, there's just a bit of text and a button.

Here's the code:

 
     package 
     com.unitedcoders.android.examples
     ;
    
     import 
     android.app.TabActivity
     ;
    
     import 
     android.os.Bundle
     ;
    
     import 
     android.view.View
     ;
    
     import 
     android.view.View.OnClickListener
     ;
    
     import 
     android.widget.Button
     ;
    
     import 
     android.widget.TabHost
     ;
    
     import 
     android.widget.Toast
     ;
    
     import 
     android.widget.ViewFlipper
     ;
    
     public class Tabs 
     extends TabActivity 
     implements OnClickListener 
     {
    
     Button doSomething
     ;
    
         TabHost tabHost
     ;
    
         ViewFlipper flipper
     ;
    
         @Override
    
     protected void onCreate
     (Bundle savedInstanceState
     ) 
     {
    
     super.
     onCreate
     (savedInstanceState
     )
     ;
    
             setContentView
     (R.
     layout.
     tablayout_1
     )
     ;
    
             doSomething 
     = 
     (
     Button
     ) findViewById
     (R.
     id.
     btn_do_something
     )
     ;
    
             doSomething.
     setOnClickListener
     (
     this
     )
     ;
    
             flipper 
     = 
     (ViewFlipper
     ) findViewById
     (R.
     id.
     layout_tab_one
     )
     ;
    
             flipper.
     setOnClickListener
     (
     this
     )
     ;
    
             tabHost 
     = getTabHost
     (
     )
     ;
    
             tabHost.
     addTab
     (tabHost.
     newTabSpec
     (
     "tab1"
     ).
     setIndicator
     (
     "Tab1"
     ).
     setContent
     (R.
     id.
     layout_tab_one
     )
     )
     ;
    
             tabHost.
     addTab
     (tabHost.
     newTabSpec
     (
     "tab2"
     ).
     setIndicator
     (
     "Tab2"
     ).
     setContent
     (R.
     id.
     layout_tab_two
     )
     )
     ;
    
             tabHost.
     setCurrentTab
     (
     0
     )
     ;
    
     }
    
         @Override
    
     public void onClick
     (
     View v
     ) 
     {
    
     // show a toast in second tab
    
     if 
     (v 
     == doSomething
     ) 
     {
    
                 Toast.
     makeText
     (getApplicationContext
     (
     ), 
     "doing something", Toast.
     LENGTH_SHORT
     ).
     show
     (
     )
     ;
    
     }
    
     // toggle TextView in first tab
    
     if 
     (v 
     == flipper
     ) 
     {
    
                 flipper.
     showNext
     (
     )
     ;
    
     }
    
     }
    
     }

and the layout that goes with it:

 
     <?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_width="fill_parent" android:layout_height="wrap_content" />
    
     <FrameLayout android:id="@android:id/tabcontent"
    
                             android:layout_width="fill_parent" android:layout_height="fill_parent">
    
     <ViewFlipper android:id="@+id/layout_tab_one"
    
                                     android:layout_width="fill_parent" android:layout_height="fill_parent">
    
     <TextView android:id="@+id/tabone1" android:layout_width="fill_parent"
    
                                             android:layout_height="fill_parent" android:text="this is a tab one" />
    
     <TextView android:id="@+id/tabone2" android:layout_width="fill_parent"
    
                                             android:layout_height="fill_parent" android:text="this is the other tab one" />
    
     </ViewFlipper>
    
     <LinearLayout android:id="@+id/layout_tab_two"
    
                                     android:orientation="vertical" android:layout_width="fill_parent"
    
                                     android:layout_height="fill_parent">
    
     <TextView android:id="@+id/textview2" android:layout_width="fill_parent"
    
                                             android:layout_height="wrap_content" android:text="this is a tab two"/>
    
     <Button android:id="@+id/btn_do_something" android:text="do something"
    
                                             android:layout_width="fill_parent" android:layout_height="wrap_content"/>
    
     </LinearLayout>
    
     </FrameLayout>
    
     </LinearLayout>
    
     </TabHost>