The technical principles of the technical principles of the Android Support Library View Pager framework in the Java class library ES)

The technical principle analysis of the technical principles of Android Support Library View Pager framework in the Java class library Overview: Android Support Library is a compatible library provided to solve the fragmentation of the Android platform version.Among them, the SUPPORT LIBRARARARARARARRAN PAGER framework is a component that can switch the effect to switching the page to the application in the application.This article will analyze the technical principles of the SUPPORT Library View Page framework and provide the corresponding Java code example. 1. Use of SUPPORT LIBRARY VIEW PAGER In Android development, the page switching effect is very easy to use the SUPPORT LIBRARY View Pages.First, make sure your project has been introduced to the support library dependence.Then, follow the steps below: 1. Define the ViewPager control in the XML layout file: <androidx.viewpager.widget.ViewPager android:id="@+id/viewPager" android:layout_width="match_parent" android:layout_height="match_parent" /> 2. Get the ViewPager instance in Activity or Fragment: ViewPager viewPager = findViewById(R.id.viewPager); 3. Create a Pageradapter adapter class to manage the ViewPager page: class MyPagerAdapter extends PagerAdapter { // Manage the number of pages of ViewPager @Override public int getCount() { return 3; } // Decate whether the current view is related to the object @Override public boolean isViewFromObject(View view, Object object) { return view == object; } // The page at the specified position of the designated position @Override public Object instantiateItem(ViewGroup container, int position) { // Create a page view and add it to the container View pageView = LayoutInflater.from(container.getContext()).inflate(R.layout.page_layout, container, false); container.addView(pageView); return pageView; } // Destroy the page of the specified location @Override public void destroyItem(ViewGroup container, int position, Object object) { container.removeView((View) object); } } 4. Set the Pageradapter adapter to ViewPager: viewPager.setAdapter(new MyPagerAdapter()); At this point, the basic use of SUPPORT LIBRARY View Pages. Second, the technical analysis of the technical principles of support library view pager The core of the SUPPORT Library View Page framework is the ViewPager class.It manages the Pageradapter adapter to achieve the function of switching on the left and right sliding page.The following is an analysis of its technical principles: 1. Manage page: The ViewPager class manages multiple pages through the Pageradapter adapter.Pageradapter is an abstract class that needs to customize a class to inherit it and rewrite the method.Among them, the number of getCount () method returns the number of pages management pages, ISViewFromObject () method determines whether the current view is related to the object, the page of the InstantiaTeItem () method to instantiated the specified position, and the DESTROYITEM () method destroys the page of the specified position. 2. Page cache: The ViewPager class caches the current page and its adjacent page items by default by default.In this way, the fluency of page switching can be improved and memory occupation can be reduced.You can adjust the number of cache pages by setting the setoffscreenPagelimit () method. 3. Page switching effect: The ViewPager class achieves the animation effect of page switching through the PageTransFormer interface and the setcurrenTitem () method.The PageTransFormer interface defines two abstract methods: TransformPage () and TransformLayoutparams (), which are used to set the animation effects and layout parameters when setting page switching. Through the above key technical principles, the SUPPORT LIBRARY View Page framework has successfully achieved the effect of switching on the left and right sliding page in Android applications. in conclusion: In Android development, the SUPPORT LIBRARY View Page framework provides a simple and powerful way to achieve page switching effects.Through the support of technical principles such as adapter management page, page cache, and page switching animation, View Pages is widely used in actual projects.Developers can customize the effects of adapters and page switching to achieve more personalized page switching effects.