Java tutorial
/* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.app; import android.os.Bundle; import android.os.Handler; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.TextView; /** * A fragment that displays a list of items by binding to a data source such as * an array or Cursor, and exposes event handlers when the user selects an item. * <p> * ListFragment hosts a {@link android.widget.ListView ListView} object that can * be bound to different data sources, typically either an array or a Cursor * holding query results. Binding, screen layout, and row layout are discussed * in the following sections. * <p> * <strong>Screen Layout</strong> * </p> * <p> * ListFragment has a default layout that consists of a single list view. * However, if you desire, you can customize the fragment layout by returning * your own view hierarchy from {@link #onCreateView}. * To do this, your view hierarchy <em>must</em> contain a ListView object with the * id "@android:id/list" (or {@link android.R.id#list} if it's in code) * <p> * Optionally, your view hierarchy can contain another view object of any type to * display when the list view is empty. This "empty list" notifier must have an * id "android:empty". Note that when an empty view is present, the list view * will be hidden when there is no data to display. * <p> * The following code demonstrates an (ugly) custom list layout. It has a list * with a green background, and an alternate red "no data" message. * </p> * * <pre> * <?xml version="1.0" encoding="utf-8"?> * <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" * android:orientation="vertical" * android:layout_width="match_parent" * android:layout_height="match_parent" * android:paddingLeft="8dp" * android:paddingRight="8dp"> * * <ListView android:id="@id/android:list" * android:layout_width="match_parent" * android:layout_height="match_parent" * android:background="#00FF00" * android:layout_weight="1" * android:drawSelectorOnTop="false"/> * * <TextView android:id="@id/android:empty" * android:layout_width="match_parent" * android:layout_height="match_parent" * android:background="#FF0000" * android:text="No data"/> * </LinearLayout> * </pre> * * <p> * <strong>Row Layout</strong> * </p> * <p> * You can specify the layout of individual rows in the list. You do this by * specifying a layout resource in the ListAdapter object hosted by the fragment * (the ListAdapter binds the ListView to the data; more on this later). * <p> * A ListAdapter constructor takes a parameter that specifies a layout resource * for each row. It also has two additional parameters that let you specify * which data field to associate with which object in the row layout resource. * These two parameters are typically parallel arrays. * </p> * <p> * Android provides some standard row layout resources. These are in the * {@link android.R.layout} class, and have names such as simple_list_item_1, * simple_list_item_2, and two_line_list_item. The following layout XML is the * source for the resource two_line_list_item, which displays two data * fields,one above the other, for each list row. * </p> * * <pre> * <?xml version="1.0" encoding="utf-8"?> * <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" * android:layout_width="match_parent" * android:layout_height="wrap_content" * android:orientation="vertical"> * * <TextView android:id="@+id/text1" * android:textSize="16sp" * android:textStyle="bold" * android:layout_width="match_parent" * android:layout_height="wrap_content"/> * * <TextView android:id="@+id/text2" * android:textSize="16sp" * android:layout_width="match_parent" * android:layout_height="wrap_content"/> * </LinearLayout> * </pre> * * <p> * You must identify the data bound to each TextView object in this layout. The * syntax for this is discussed in the next section. * </p> * <p> * <strong>Binding to Data</strong> * </p> * <p> * You bind the ListFragment's ListView object to data using a class that * implements the {@link android.widget.ListAdapter ListAdapter} interface. * Android provides two standard list adapters: * {@link android.widget.SimpleAdapter SimpleAdapter} for static data (Maps), * and {@link android.widget.SimpleCursorAdapter SimpleCursorAdapter} for Cursor * query results. * </p> * <p> * You <b>must</b> use * {@link #setListAdapter(ListAdapter) ListFragment.setListAdapter()} to * associate the list with an adapter. Do not directly call * {@link ListView#setAdapter(ListAdapter) ListView.setAdapter()} or else * important initialization will be skipped. * </p> * * @see #setListAdapter * @see android.widget.ListView * * @deprecated Use the <a href="{@docRoot}tools/extras/support-library.html">Support Library</a> * {@link android.support.v4.app.ListFragment} for consistent behavior across all devices * and access to <a href="{@docRoot}topic/libraries/architecture/lifecycle.html">Lifecycle</a>. */ @Deprecated public class ListFragment extends Fragment { final private Handler mHandler = new Handler(); final private Runnable mRequestFocus = new Runnable() { public void run() { mList.focusableViewAvailable(mList); } }; final private AdapterView.OnItemClickListener mOnClickListener = new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View v, int position, long id) { onListItemClick((ListView) parent, v, position, id); } }; ListAdapter mAdapter; ListView mList; View mEmptyView; TextView mStandardEmptyView; View mProgressContainer; View mListContainer; CharSequence mEmptyText; boolean mListShown; public ListFragment() { } /** * Provide default implementation to return a simple list view. Subclasses * can override to replace with their own layout. If doing so, the * returned view hierarchy <em>must</em> have a ListView whose id * is {@link android.R.id#list android.R.id.list} and can optionally * have a sibling view id {@link android.R.id#empty android.R.id.empty} * that is to be shown when the list is empty. * * <p>If you are overriding this method with your own custom content, * consider including the standard layout {@link android.R.layout#list_content} * in your layout file, so that you continue to retain all of the standard * behavior of ListFragment. In particular, this is currently the only * way to have the built-in indeterminant progress state be shown. */ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(com.android.internal.R.layout.list_content, container, false); } /** * Attach to list view once the view hierarchy has been created. */ @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); ensureList(); } /** * Detach from list view. */ @Override public void onDestroyView() { mHandler.removeCallbacks(mRequestFocus); mList = null; mListShown = false; mEmptyView = mProgressContainer = mListContainer = null; mStandardEmptyView = null; super.onDestroyView(); } /** * This method will be called when an item in the list is selected. * Subclasses should override. Subclasses can call * getListView().getItemAtPosition(position) if they need to access the * data associated with the selected item. * * @param l The ListView where the click happened * @param v The view that was clicked within the ListView * @param position The position of the view in the list * @param id The row id of the item that was clicked */ public void onListItemClick(ListView l, View v, int position, long id) { } /** * Provide the cursor for the list view. */ public void setListAdapter(ListAdapter adapter) { boolean hadAdapter = mAdapter != null; mAdapter = adapter; if (mList != null) { mList.setAdapter(adapter); if (!mListShown && !hadAdapter) { // The list was hidden, and previously didn't have an // adapter. It is now time to show it. setListShown(true, getView().getWindowToken() != null); } } } /** * Set the currently selected list item to the specified * position with the adapter's data * * @param position */ public void setSelection(int position) { ensureList(); mList.setSelection(position); } /** * Get the position of the currently selected list item. */ public int getSelectedItemPosition() { ensureList(); return mList.getSelectedItemPosition(); } /** * Get the cursor row ID of the currently selected list item. */ public long getSelectedItemId() { ensureList(); return mList.getSelectedItemId(); } /** * Get the fragment's list view widget. */ public ListView getListView() { ensureList(); return mList; } /** * The default content for a ListFragment has a TextView that can * be shown when the list is empty. If you would like to have it * shown, call this method to supply the text it should use. */ public void setEmptyText(CharSequence text) { ensureList(); if (mStandardEmptyView == null) { throw new IllegalStateException("Can't be used with a custom content view"); } mStandardEmptyView.setText(text); if (mEmptyText == null) { mList.setEmptyView(mStandardEmptyView); } mEmptyText = text; } /** * Control whether the list is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * * <p>Applications do not normally need to use this themselves. The default * behavior of ListFragment is to start with the list not being shown, only * showing it once an adapter is given with {@link #setListAdapter(ListAdapter)}. * If the list at that point had not been shown, when it does get shown * it will be do without the user ever seeing the hidden state. * * @param shown If true, the list view is shown; if false, the progress * indicator. The initial value is true. */ public void setListShown(boolean shown) { setListShown(shown, true); } /** * Like {@link #setListShown(boolean)}, but no animation is used when * transitioning from the previous state. */ public void setListShownNoAnimation(boolean shown) { setListShown(shown, false); } /** * Control whether the list is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * * @param shown If true, the list view is shown; if false, the progress * indicator. The initial value is true. * @param animate If true, an animation will be used to transition to the * new state. */ private void setListShown(boolean shown, boolean animate) { ensureList(); if (mProgressContainer == null) { throw new IllegalStateException("Can't be used with a custom content view"); } if (mListShown == shown) { return; } mListShown = shown; if (shown) { if (animate) { mProgressContainer .startAnimation(AnimationUtils.loadAnimation(getContext(), android.R.anim.fade_out)); mListContainer.startAnimation(AnimationUtils.loadAnimation(getContext(), android.R.anim.fade_in)); } else { mProgressContainer.clearAnimation(); mListContainer.clearAnimation(); } mProgressContainer.setVisibility(View.GONE); mListContainer.setVisibility(View.VISIBLE); } else { if (animate) { mProgressContainer .startAnimation(AnimationUtils.loadAnimation(getContext(), android.R.anim.fade_in)); mListContainer.startAnimation(AnimationUtils.loadAnimation(getContext(), android.R.anim.fade_out)); } else { mProgressContainer.clearAnimation(); mListContainer.clearAnimation(); } mProgressContainer.setVisibility(View.VISIBLE); mListContainer.setVisibility(View.GONE); } } /** * Get the ListAdapter associated with this fragment's ListView. */ public ListAdapter getListAdapter() { return mAdapter; } private void ensureList() { if (mList != null) { return; } View root = getView(); if (root == null) { throw new IllegalStateException("Content view not yet created"); } if (root instanceof ListView) { mList = (ListView) root; } else { mStandardEmptyView = (TextView) root.findViewById(com.android.internal.R.id.internalEmpty); if (mStandardEmptyView == null) { mEmptyView = root.findViewById(android.R.id.empty); } else { mStandardEmptyView.setVisibility(View.GONE); } mProgressContainer = root.findViewById(com.android.internal.R.id.progressContainer); mListContainer = root.findViewById(com.android.internal.R.id.listContainer); View rawListView = root.findViewById(android.R.id.list); if (!(rawListView instanceof ListView)) { throw new RuntimeException( "Content has view with id attribute 'android.R.id.list' " + "that is not a ListView class"); } mList = (ListView) rawListView; if (mList == null) { throw new RuntimeException( "Your content must have a ListView whose id attribute is " + "'android.R.id.list'"); } if (mEmptyView != null) { mList.setEmptyView(mEmptyView); } else if (mEmptyText != null) { mStandardEmptyView.setText(mEmptyText); mList.setEmptyView(mStandardEmptyView); } } mListShown = true; mList.setOnItemClickListener(mOnClickListener); if (mAdapter != null) { ListAdapter adapter = mAdapter; mAdapter = null; setListAdapter(adapter); } else { // We are starting without an adapter, so assume we won't // have our data right away and start with the progress indicator. if (mProgressContainer != null) { setListShown(false, false); } } mHandler.post(mRequestFocus); } }