Java tutorial
package android.support.v4.app; import android.content.Intent; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.preference.Preference; import android.preference.PreferenceManager; import android.preference.PreferenceScreen; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ListView; public class PreferenceFragment extends ListFragment implements PreferenceManagerCompat.OnPreferenceTreeClickListener { private static final String PREFERENCES_TAG = "android:preferences"; /** * The starting request code given out to preference framework. */ private static final int FIRST_REQUEST_CODE = 100; private static final int MSG_BIND_PREFERENCES = 1; /** * Interface that PreferenceFragment's containing activity should * implement to be able to process preference items that wish to * switch to a new fragment. */ public interface OnPreferenceStartFragmentCallback { /** * Called when the user has clicked on a Preference that has * a fragment class name associated with it. The implementation * to should instantiate and switch to an instance of the given * fragment. */ boolean onPreferenceStartFragment(PreferenceFragment caller, Preference pref); } private Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_BIND_PREFERENCES: bindPreferences(); break; } } }; final private Runnable mRequestFocus = new Runnable() { public void run() { if (getListView() != null) { getListView().focusableViewAvailable(getListView()); } } }; private PreferenceManager mPreferenceManager; private boolean mHavePrefs; private boolean mInitDone; @Override public void onCreate(Bundle paramBundle) { super.onCreate(paramBundle); mPreferenceManager = PreferenceManagerCompat.newInstance(getActivity(), FIRST_REQUEST_CODE); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View root = super.onCreateView(inflater, container, savedInstanceState); ListView listView = (ListView) root.findViewById(android.R.id.list); if (listView != null) { int horizontalPadding = dpToPx(8); listView.setPadding(horizontalPadding, 0, horizontalPadding, 0); listView.setClipToPadding(false); listView.setScrollBarStyle(0x02000000); // outsideOverlay } return root; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); if (mHavePrefs) { bindPreferences(); } mInitDone = true; if (savedInstanceState != null) { Bundle container = savedInstanceState.getBundle(PREFERENCES_TAG); if (container != null) { final PreferenceScreen preferenceScreen = getPreferenceScreen(); if (preferenceScreen != null) { preferenceScreen.restoreHierarchyState(container); } } } } @Override public void onStart() { super.onStart(); PreferenceManagerCompat.setOnPreferenceTreeClickListener(mPreferenceManager, this); } @Override public void onStop() { super.onStop(); PreferenceManagerCompat.dispatchActivityStop(mPreferenceManager); PreferenceManagerCompat.setOnPreferenceTreeClickListener(mPreferenceManager, null); } @Override public void onDestroyView() { mHandler.removeCallbacks(mRequestFocus); mHandler.removeMessages(MSG_BIND_PREFERENCES); super.onDestroyView(); } @Override public void onDestroy() { super.onDestroy(); PreferenceManagerCompat.dispatchActivityDestroy(mPreferenceManager); } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); final PreferenceScreen preferenceScreen = getPreferenceScreen(); if (preferenceScreen != null) { Bundle container = new Bundle(); preferenceScreen.saveHierarchyState(container); outState.putBundle(PREFERENCES_TAG, container); } } @Override public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); PreferenceManagerCompat.dispatchActivityResult(mPreferenceManager, requestCode, resultCode, data); } @Override public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) { if (getActivity() instanceof OnPreferenceStartFragmentCallback) { return ((OnPreferenceStartFragmentCallback) getActivity()).onPreferenceStartFragment(this, preference); } return false; } protected int dpToPx(int dp) { float density = getActivity().getResources().getDisplayMetrics().density; return Math.round((float) dp * density); } /** * Returns the {@link PreferenceManager} used by this fragment. * @return The {@link PreferenceManager}. */ public PreferenceManager getPreferenceManager() { return mPreferenceManager; } /** * Sets the root of the preference hierarchy that this fragment is showing. * * @param preferenceScreen The root {@link PreferenceScreen} of the preference hierarchy. */ public void setPreferenceScreen(PreferenceScreen preferenceScreen) { if (PreferenceManagerCompat.setPreferences(mPreferenceManager, preferenceScreen) && preferenceScreen != null) { mHavePrefs = true; if (mInitDone) { postBindPreferences(); } } } /** * Gets the root of the preference hierarchy that this fragment is showing. * * @return The {@link PreferenceScreen} that is the root of the preference * hierarchy. */ public PreferenceScreen getPreferenceScreen() { return PreferenceManagerCompat.getPreferenceScreen(mPreferenceManager); } /** * Adds preferences from activities that match the given {@link Intent}. * * @param intent The {@link Intent} to query activities. */ public void addPreferencesFromIntent(Intent intent) { requirePreferenceManager(); setPreferenceScreen( PreferenceManagerCompat.inflateFromIntent(mPreferenceManager, intent, getPreferenceScreen())); } /** * Inflates the given XML resource and adds the preference hierarchy to the current * preference hierarchy. * * @param preferencesResId The XML resource ID to inflate. */ public void addPreferencesFromResource(int preferencesResId) { requirePreferenceManager(); setPreferenceScreen(PreferenceManagerCompat.inflateFromResource(mPreferenceManager, getActivity(), preferencesResId, getPreferenceScreen())); } /** * Finds a {@link Preference} based on its key. * * @param key The key of the preference to retrieve. * @return The {@link Preference} with the key, or null. * @see PreferenceGroup#findPreference(CharSequence) */ public Preference findPreference(CharSequence key) { if (mPreferenceManager == null) { return null; } return mPreferenceManager.findPreference(key); } private void requirePreferenceManager() { if (mPreferenceManager == null) { throw new RuntimeException("This should be called after super.onCreate."); } } private void postBindPreferences() { if (mHandler.hasMessages(MSG_BIND_PREFERENCES)) return; mHandler.obtainMessage(MSG_BIND_PREFERENCES).sendToTarget(); } private void bindPreferences() { final PreferenceScreen preferenceScreen = getPreferenceScreen(); if (preferenceScreen != null) { preferenceScreen.bind(getListView()); } setListShownNoAnimation(true); } }