The technical principles of the AndroidX Preference framework in the Java class library

AndroidX is an Android development support library that provides developers with component, and the Preference framework is one of them.This article will explore the technical principles of the AndroidX Preference framework in the Java class library and provide some Java code examples. The AndroidX Preference framework helps developers to quickly build a setting page in the user interface.It provides a set of UI components that are easy to use and highly customable, such as multiple selection boxes, single -selected boxes, sliders, etc., while supporting read -write operations of persistent data.By using this framework, developers can easily create, manage and display various preference settings. First, we need to introduce the dependence of the AndroidX Preference framework in Gradle: implementation 'androidx.preference:preference:1.1.1' Before using the Preference framework, we need to define a class that inherits from PreferenceFragmentCompat.This class will be the main entrance point of our settings page.For example, we can create a class called Settingsfragment: public class SettingsFragment extends PreferenceFragmentCompat { @Override public void onCreatePreferences(Bundle savedInstanceState, String rootKey) { setPreferencesFromResource(R.xml.preferences, rootKey); } // Add other custom methods and logic } Then we need to create a XML file to define our preference settings page.This file will contain a variety of different Preference elements, such as SwitchPreference, ListPreference, etc.For example, we can create a file called Preferences.xml: <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <SwitchPreference android:key="notifications" Android: Title = "Receive Notice" Android: Summary = "Enable or Disable Notice" android:defaultValue="true" /> <ListPreference android:key="language" Android: Title = "Language Settings" Android: Summary = "Select your preferred language" android:entries="@array/language_options" android:entryValues="@array/language_values" android:defaultValue="en" /> // Add other Preference elements </PreferenceScreen> Each preference element in XML has a unique key attribute to identify the preference.When the user changes the settings, we can use this key to obtain or save the value of the preference settings. Next, in our Activity or Fragment, we can instantly instance the SettingsFragment class and display it in the user interface: public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); getSupportFragmentManager() .beginTransaction() .replace(R.id.container, new SettingsFragment()) .commit(); } // Add other custom code and logic } Now, when we run the application, we will see a interface that contains our definition settings.Users can change the settings by interacting with these UI elements, and these changes will be preserved for a long time. Through the above code example, we can see some of the main principles of the AndroidX Preference framework.First of all, we define the structure and characteristics of the preference for setting the page.We then associate these definitions with the UI components provided in the Preference framework.Finally, we display these UI components in the user interface and handle the user's interactive operation. To sum up, the technical principles of the AndroidX Preference framework in the Java class library include defining the structure of the preference to set the page, using the PreferenceFragmentCompat class as the entrance point, creating the XML file to define the UI component of the settings page, the key and value of the associated UI component and the preference settings settingsAnd instantiated in Activity or Fragment and show the PreferenceFragment.By understanding these principles, developers can better use the Preference framework to create user -friendly settings pages.