Android Support Library View Pager framework technical principles and practical applications

Android Support Library View Page framework technical principles and practical applications Summary: The ViewPager framework in Android Support Library is a flexible component to display slidy view pages in the application.This article will introduce the technical principles of the ViewPager framework and how to apply the framework in practical applications.At the same time, some Java code examples will be provided to help readers better understand and use the ViewPager framework. 1. Framework Overview ViewPage is a component in Android Support Library that allows users to switch between different view pages by sliding gestures.It is usually used to build a scene of the homepage, setting page, and help page that needs to display multiple pages.The ViewPager framework provides a simple and powerful way to achieve these functions. 2. Technical principles The core principle of the ViewPager framework is to provide view pages through Adapter, and at the same time, the creation, destruction and refreshing operation of the Adapter management page.Adapter is a class that implements the Pageradapter interface. It is responsible for creating a view of each page and adding it to the viewpager for display. The Pageradapter interface defines the following key methods: -` Getcount () `: Return to the number of pages to be displayed. -`isViewFromobject (view, object)`: determine whether the given view comes from the specified page object. -` InstantiaTeitem (Container, Position) `: Create a page for the specified location and add it to the container. -` Destroyitem (Container, POSITION, OBject) `: Destroy the page of the specified location. By achieving these methods of the Pageradapter interface, we can customize the implementation of an Adapter that is suitable for our needs, so as to achieve a variety of unique page display effects. 3. Practical application In practical applications, we can use the ViewPager framework through the following steps: Step 1: Add ViewPager components to the XML layout file. <androidx.viewpager.widget.ViewPager android:id="@+id/viewPager" android:layout_width="match_parent" android:layout_height="match_parent"/> Step 2: Initialize the ViewPager object in the Java code and create an adapter. ViewPager viewPager = findViewById(R.id.viewPager); MyPagerAdapter adapter = new MyPagerAdapter(); viewPager.setAdapter(adapter); Step 3: Custom adapter to implement the Pageradapter interface. class MyPagerAdapter extends PagerAdapter { private static final int PAGE_COUNT = 3; private static final int[] PAGE_LAYOUTS = {R.layout.page1, R.layout.page2, R.layout.page3}; @Override public int getCount() { return PAGE_COUNT; } @Override public boolean isViewFromObject(View view, Object object) { return view == object; } @Override public Object instantiateItem(ViewGroup container, int position) { LayoutInflater inflater = LayoutInflater.from(container.getContext()); View view = inflater.inflate(PAGE_LAYOUTS[position], container, false); container.addView(view); return view; } @Override public void destroyItem(ViewGroup container, int position, Object object) { container.removeView((View) object); } } In the above examples, the custom appliance inherits the Pageradapter, and the relevant methods are implemented as needed.We can freely extend the function of the adapter according to actual needs, such as adding data sources and implementing page refresh. in conclusion: This article introduces the technical principles and practical applications of the ViewPager framework in Android Support Library.The ViewPager framework manages the creation and destruction of the page through ADAPTER, providing a simple and powerful way to achieve the function of multi -page display.By writing a custom adapter, we can customize the effect of customized pages for different needs.It is hoped that readers can have a deeper understanding of the ViewPager framework through this article and can flexibly apply the framework in practical applications. references: - Android Developers. ViewPager. https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.html Appendix: The XML layout files in the Java code example (Page1.xml, Page2.xml, and Page3.xml) should be created according to the specific situation. Note: This article refers to the official documents and related technical information, and sort out and supplement it.For more details, see the official document or other related information.