/*
* Copyright (C) 2006 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.database.Cursor;
import android.os.Bundle;
import java.util.List;
import android.view.ContextMenu;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnCreateContextMenuListener;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.SimpleCursorTreeAdapter;
import android.widget.SimpleExpandableListAdapter;
import java.util.Map;
/**
* An activity that displays an expandable list of items by binding to a data
* source implementing the ExpandableListAdapter, and exposes event handlers
* when the user selects an item.
* <p>
* ExpandableListActivity hosts a
* {@link android.widget.ExpandableListView ExpandableListView} object that can
* be bound to different data sources that provide a two-levels of data (the
* top-level is group, and below each group are children). Binding, screen
* layout, and row layout are discussed in the following sections.
* <p>
* <strong>Screen Layout</strong>
* </p>
* <p>
* ExpandableListActivity has a default layout that consists of a single,
* full-screen, centered expandable list. However, if you desire, you can
* customize the screen layout by setting your own view layout with
* setContentView() in onCreate(). To do this, your own view MUST contain an
* ExpandableListView object with the id "@android:id/list" (or
* {@link android.R.id#list} if it's in code)
* <p>
* Optionally, your custom view 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 expandable
* list view will be hidden when there is no data to display.
* <p>
* The following code demonstrates an (ugly) custom screen 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">
*
* <ExpandableListView 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>
* The {@link ExpandableListAdapter} set in the {@link ExpandableListActivity}
* via {@link #setListAdapter(ExpandableListAdapter)} provides the {@link View}s
* for each row. This adapter has separate methods for providing the group
* {@link View}s and child {@link View}s. There are a couple provided
* {@link ExpandableListAdapter}s that simplify use of adapters:
* {@link SimpleCursorTreeAdapter} and {@link SimpleExpandableListAdapter}.
* <p>
* With these, you can specify the layout of individual rows for groups and
* children in the list. These constructor takes a few parameters that specify
* layout resources for groups and children. It also has additional parameters
* that let you specify which data field to associate with which object in the
* row layout resource. The {@link SimpleCursorTreeAdapter} fetches data from
* {@link Cursor}s and the {@link SimpleExpandableListAdapter} fetches data
* from {@link List}s of {@link Map}s.
* </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 ExpandableListActivity's ExpandableListView object to data using
* a class that implements the
* {@link android.widget.ExpandableListAdapter ExpandableListAdapter} interface.
* Android provides two standard list adapters:
* {@link android.widget.SimpleExpandableListAdapter SimpleExpandableListAdapter}
* for static data (Maps), and
* {@link android.widget.SimpleCursorTreeAdapter SimpleCursorTreeAdapter} for
* Cursor query results.
* </p>
*
* @see #setListAdapter
* @see android.widget.ExpandableListView
*/
public class ExpandableListActivity extends Activity implements
OnCreateContextMenuListener,
ExpandableListView.OnChildClickListener, ExpandableListView.OnGroupCollapseListener,
ExpandableListView.OnGroupExpandListener {
ExpandableListAdapter mAdapter;
ExpandableListView mList;
boolean mFinishedStart = false;
/**
* Override this to populate the context menu when an item is long pressed. menuInfo
* will contain an {@link android.widget.ExpandableListView.ExpandableListContextMenuInfo}
* whose packedPosition is a packed position
* that should be used with {@link ExpandableListView#getPackedPositionType(long)} and
* the other similar methods.
* <p>
* {@inheritDoc}
*/
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
}
/**
* Override this for receiving callbacks when a child has been clicked.
* <p>
* {@inheritDoc}
*/
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition,
int childPosition, long id) {
return false;
}
/**
* Override this for receiving callbacks when a group has been collapsed.
*/
public void onGroupCollapse(int groupPosition) {
}
/**
* Override this for receiving callbacks when a group has been expanded.
*/
public void onGroupExpand(int groupPosition) {
}
/**
* Ensures the expandable list view has been created before Activity restores all
* of the view states.
*
*@see Activity#onRestoreInstanceState(Bundle)
*/
@Override
protected void onRestoreInstanceState(Bundle state) {
ensureList();
super.onRestoreInstanceState(state);
}
/**
* Updates the screen state (current list and other views) when the
* content changes.
*
* @see Activity#onContentChanged()
*/
@Override
public void onContentChanged() {
super.onContentChanged();
View emptyView = findViewById(com.android.internal.R.id.empty);
mList = (ExpandableListView)findViewById(com.android.internal.R.id.list);
if (mList == null) {
throw new RuntimeException(
"Your content must have a ExpandableListView whose id attribute is " +
"'android.R.id.list'");
}
if (emptyView != null) {
mList.setEmptyView(emptyView);
}
mList.setOnChildClickListener(this);
mList.setOnGroupExpandListener(this);
mList.setOnGroupCollapseListener(this);
if (mFinishedStart) {
setListAdapter(mAdapter);
}
mFinishedStart = true;
}
/**
* Provide the adapter for the expandable list.
*/
public void setListAdapter(ExpandableListAdapter adapter) {
synchronized (this) {
ensureList();
mAdapter = adapter;
mList.setAdapter(adapter);
}
}
/**
* Get the activity's expandable list view widget. This can be used to get the selection,
* set the selection, and many other useful functions.
*
* @see ExpandableListView
*/
public ExpandableListView getExpandableListView() {
ensureList();
return mList;
}
/**
* Get the ExpandableListAdapter associated with this activity's
* ExpandableListView.
*/
public ExpandableListAdapter getExpandableListAdapter() {
return mAdapter;
}
private void ensureList() {
if (mList != null) {
return;
}
setContentView(com.android.internal.R.layout.expandable_list_content);
}
/**
* Gets the ID of the currently selected group or child.
*
* @return The ID of the currently selected group or child.
*/
public long getSelectedId() {
return mList.getSelectedId();
}
/**
* Gets the position (in packed position representation) of the currently
* selected group or child. Use
* {@link ExpandableListView#getPackedPositionType},
* {@link ExpandableListView#getPackedPositionGroup}, and
* {@link ExpandableListView#getPackedPositionChild} to unpack the returned
* packed position.
*
* @return A packed position representation containing the currently
* selected group or child's position and type.
*/
public long getSelectedPosition() {
return mList.getSelectedPosition();
}
/**
* Sets the selection to the specified child. If the child is in a collapsed
* group, the group will only be expanded and child subsequently selected if
* shouldExpandGroup is set to true, otherwise the method will return false.
*
* @param groupPosition The position of the group that contains the child.
* @param childPosition The position of the child within the group.
* @param shouldExpandGroup Whether the child's group should be expanded if
* it is collapsed.
* @return Whether the selection was successfully set on the child.
*/
public boolean setSelectedChild(int groupPosition, int childPosition, boolean shouldExpandGroup) {
return mList.setSelectedChild(groupPosition, childPosition, shouldExpandGroup);
}
/**
* Sets the selection to the specified group.
* @param groupPosition The position of the group that should be selected.
*/
public void setSelectedGroup(int groupPosition) {
mList.setSelectedGroup(groupPosition);
}
}
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