Now that you have two implementations of TabHelper
and CompatTab
—one for Android 3.0 and later and one for earlier versions of the platform—it's time to do something with these implementations. This lesson discusses creating the
logic for switching between these implementations, creating version-aware layouts, and finally using the backward-compatible UI component.http://blog.csdn.net/sergeycao
Add the Switching Logic
The TabHelper
abstract class acts as a
factory for creating version-appropriate TabHelper
and CompatTab
instances, based on the current device's platform version:
public abstract class TabHelper {
...
// Usage is TabHelper.createInstance(activity)
public static TabHelper createInstance(FragmentActivity activity) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
return new TabHelperHoneycomb(activity);
} else {
return new TabHelperEclair(activity);
}
}
// Usage is mTabHelper.newTab("tag")
public CompatTab newTab(String tag) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
return new CompatTabHoneycomb(mActivity, tag);
} else {
return new CompatTabEclair(mActivity, tag);
}
}
...
}
Create a Version-Aware Activity Layout
The next step is to provide layouts for your activity that can support the two tab implementations. For the older implementation (TabHelperEclair
), you need to ensure that your activity layout contains a
TabWidget
and TabHost
, along with a container for tab contents:
res/layout/main.xml:
<!-- This layout is for API level 5-10 only. -->
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp">
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
</LinearLayout>
</TabHost>
For the TabHelperHoneycomb
implementation, all you need is a
FrameLayout
to contain the tab contents, since the tab indicators are provided by the
ActionBar
:
res/layout-v11/main.xml:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabcontent"
android:layout_width="match_parent"
android:layout_height="match_parent" />
At runtime, Android will decide which version of the main.xml
layout to inflate depending on the platform version. This is the same logic shown in the previous section to determine which
TabHelper
implementation to use.
Use TabHelper in Your Activity
In your activity's onCreate()
method, you can obtain a
TabHelper
object and add tabs with the following code:
@Override
public void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.main);
TabHelper tabHelper = TabHelper.createInstance(this);
tabHelper.setUp();
CompatTab photosTab = tabHelper
.newTab("photos")
.setText(R.string.tab_photos);
tabHelper.addTab(photosTab);
CompatTab videosTab = tabHelper
.newTab("videos")
.setText(R.string.tab_videos);
tabHelper.addTab(videosTab);
}
When running the application, this code inflates the correct activity layout and instantiates either a
TabHelperHoneycomb
or TabHelperEclair
object. The concrete class that's actually used is opaque to the activity, since they share the common
TabHelper
interface.
Below are two screenshots of this implementation running on an Android 2.3 and Android 4.0 device.
Figure 1. Example screenshots of backward-compatible tabs running on an Android 2.3 device (using
TabHelperEclair
) and an Android 4.0 device (using TabHelperHoneycomb
).
分享到:
相关推荐
Next, select the "Raize Components 6.x (Data-Aware)" package from the Design Packages list and click the Remove button. Again, a message box will be displayed to confirm your request--press OK. Next, ...
These are SQLDataDrivers that can deliver queries to the server using corresponding drivers of the access to datas. -------------------- 2. Installation Library -------------------- ------------...
Also, if you are replacing an existing version of SQLMemTable, please remove all files and the package of the prior version before running the new setup program.2) Unpack zip archive containing ...
EhLib 9.1.024 源码版本,自行编译 EhLib 9.1 Build 9.1.024 Professional Edition. ---------------------------------------------- The Library contains components and classes for Borland Delphi versions...
These are SQLDataDrivers that can deliver queries to the server using corresponding drivers of the access to datas. -------------------- 2. Installation Library -------------------- ------------...
These are SQLDataDrivers that can deliver queries to the server using corresponding drivers of the access to datas. -------------------- 2. Installation Library -------------------- ------------...
Next, select the "Raize Components 6.x (Data-Aware)" package from the Design Packages list and click the Remove button. Again, a message box will be displayed to confirm your request--press OK. Next, ...
Add splitter support to any application by using the RxSplitter component. TRxSlider and TRxSwitch are slider and switch controls respectively with the ability to change their looks. TRxSlider ...
Next, select the "Raize Components 6.x (Data-Aware)" package from the Design Packages list and click the Remove button. Again, a message box will be displayed to confirm your request--press OK. Next, ...
These interfaces support the amount of DBMSfunctionality appropriate to the data store, enabling the data storeto share its data.Using BDE in SQL Server oriented client/server applications has ...
These interfaces support the amount of DBMSfunctionality appropriate to the data store, enabling the data storeto share its data.Using BDE in SQL Server oriented client/server applications has ...
Diamond ADO is a Delphi component library, that provide high-speed performance when working with any OLE DB provider or ODBC data source. Diamond ADO uses ActiveX Data Objects 2.x (ADO) to access data...
These are SQLDataDrivers that can deliver queries to the server using corresponding drivers of the access to datas. -------------------- Installation Library -------------------- If you have ...
Add splitter support to any application by using the RxSplitter component. TRxSlider and TRxSwitch are slider and switch controls respectively with the ability to change their looks. TRxSlider ...
IMPORTANT: If installing the registered version, please be sure to always re-install/rebuild the components (VCLZip and VCLUnZip) to the component pallette (or rebuild the design time package) so that...
A scaling engine of the package has been rewritten and is PDI aware now Different displays with different DPI are supported simultaneously under Win 10 if application compiled under RAD Studio 10.2 ...
Next, select the "Raize Components 3.0 (Data-Aware)" package from the Design Packages list and click the Remove button. Again, a message box will be displayed to confirm your request--press OK. ...
The lastest version : 6.6, update date: 7 Jan. 2012, see what's new (Newly supports RAD Studio XE2, fully supports Sunisoft Skin Solutions v2) SUIPack is a suite of real WYSIWYG VCL skin components ...
(VCLZip Lite: Version 2.23 April 14th, 2002) (VCLZip Pro: Version 3.03 October 4th, 2003)IMPORTANT: If installing the registered version, please be sure to always re-install/rebuild the components ...
18)..Fixed: Possible "Unit XYZ was compiled with a different version of ABC" when using packages 19)..Fixed: FastMM shared MM compatibility 20)..Fixed: Minor bugs in stack tracing (which usually ...