本文详细介绍了Android中ListView和ExpandableListView的基础知识，包括它们的用途、关键方法、重要属性以及使用方式。着重解释了如何通过Adapter绑定数据、处理点击事件、动态加载网络数据等核心概念。
1.前言
本篇主要ExpandableListView和ListView一些基础知识点介绍，主要包括一些类和接口的使用介绍，主要是参照google 最新的API文档摘要总结的；
2.什么是ListView
是一种ViewGroup，用于滚动展示一组列表，这些列表项自动由Adapter从数据源读取数据产生特定的View填充到ListView；
当布局中的内容是动态的或者预先不可知的，可以使用AdapterView（ListView,GridView是其子类）运行时填充；
AdapterView（包括子类）使用Adapter绑定数据到自己，Adapter是数据源和AdapterView布局的中介；
3.ListView重要方法和属性：
用于垂直滚动列表视图，列表项来自ListAdapter；
类继承结构：具体的类
public class ListView extends AbsListView
java.lang.Object
↳ android.view.View
↳ android.view.ViewGroup
↳ android.widget.AdapterView<T extends android.widget.Adapter>
↳ android.widget.AbsListView
↳ android.widget.ListView
直接子类：
ExpandableListView ：用于展示两级列表；
重要的XML属性：
android:divider：两个列表项之间的分割线（可以使color或者Drawable）
android:dividerHeight：分割线的高度（厚度）
android:entries：静态引用一个数组资源，用来填充ListView的
android:footerDividersEnabled：对于footer view是否有divider
android:headerDividersEnabled:
从AbsListView继承的重要属性：
android:choiceMode:设置列表项的选择行为，是否可以选择，是否支持多选
android:listSelector ：设置列表中被选中的项的Drawable
android:textFilterEnabled：是否支持过滤
重要方法：
void addFooterView(View v)：添加固定的View到列表的底部，在setAdapter之前调用，可以添加多次，显示多个
void addFooterView(View v, Object data, boolean isSelectable)
void addHeaderView(View v)
ListAdapter getAdapter()：返回与之绑定的Adapter
void setAdapter (ListAdapter adapter) ：设置ListView的数据
long[] getCheckItemIds ()：api8过期，获取选择的多个Items的id，仅当模式不是CHOICE_MODE_NONE.有效
void setSelection (int position)：设置选定的列表项，从0开始
4.ListView相关的类：ListAdapter（也是接口）
public interface Adapter android.widget.Adapter间接子类：
ArrayAdapter<T>, BaseAdapter, CursorAdapter, HeaderViewListAdapter, ListAdapter,
ResourceCursorAdapter, SimpleAdapter, SimpleCursorAdapter,SpinnerAdapter, WrapperListAdapter
方法：
abstract int getCount()：有多少数据
abstract Object getItem(int position):获取特定位置的数据
abstract long getItemId(int position):获取特定位置的行id
abstract View getView(int position, View convertView, ViewGroup parent)：获取特定位置展示的View
abstract boolean isEmpty()：
public interface ListAdapter implements Adapter （添加了两个抽象方法） android.widget.ListAdapter
间接子类：
ArrayAdapter<T>, BaseAdapter（抽象类）, CursorAdapter（抽象类）, HeaderViewListAdapter,
ResourceCursorAdapter, SimpleAdapter, SimpleCursorAdapter, WrapperListAdapter
常用的Adapter：
public class ArrayAdapter extends BaseAdapter implements Filterable：android.widget.ArrayAdapter<T>
具体简单的Adapter类，数据源是数组，布局中有一个简单的TextView，如果想要其它View，可以重写getView方法
使用一般重写，或者使用：
public ArrayAdapter (Context context, int resource, T[] objects)：Resource布局文件必须有特定名称的textview
public ArrayAdapter (Context context, int resource, int textViewResourceId, T[] objects)
public ArrayAdapter (Context context, int resource, List<T> objects)
public ArrayAdapter (Context context, int resource, int textViewResourceId, List<T> objects)
public class SimpleCursorAdapter extends ResourceCursorAdapter：
android.support.v4.widget.SimpleCursorAdapter
构造器：
SimpleCursorAdapter(Context context, int layout, Cursor c, String[] from, int[] to, int flags)
参数：layout-定义列表项的布局文件，c-数据源cursor，可以为null（如果不可用），
from-数组定义了需要绑定的cursor数据列名，to-表明view的id，用来展示数据
flags-决定adapter的行为，FLAG_AUTO_REQUERY（过期，不建议使用，会在主线程中获取数据，阻塞） FLAG_REGISTER_CONTENT_OBSERVER（添加内容监听器，当通知到来，
调用onContentChanged方法，小心内存泄露，当使用CursorAdapter[CursorLoader]时，不需要该标志；
方法：
Cursor swapCursor(Cursor c)：换入一个新的Cursor，返回旧的cursor【未关闭】，如果cursor为null或者新的和旧的一样返回null
public abstract class CursorAdapter extends BaseAdapter implements Filterable
5.ListView使用方式：【读取本地数据】
- 需要ListView；
- 需要ListAdapter及其子类；
- 如果Adpater数据发生变化，应该调用notifyDataSetChanged()方法；
定制每一项文本内容，可以重写数组中每个对象的toString方法；
定制ListView每一项的视图，可以重写getView方法；
ArrayAdapter adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, myStringArray);
ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(adapter);ListView+SimpleCursorAdapter方法：
String[] fromColumns = {ContactsContract.Data.DISPLAY_NAME,
ContactsContract.CommonDataKinds.Phone.NUMBER};
int[] toViews = {R.id.display_name, R.id.phone_number};
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.person_name_and_number, cursor, fromColumns, toViews, 0);
ListView listView = getListView();
listView.setAdapter(adapter);处理点击事件：实现AdapterView.onItemClickListener接口
<pre name="code" class="java"> // Create a message handling object as an anonymous class.
private OnItemClickListener mMessageClickedHandler = new OnItemClickListener() {
public void onItemClick(AdapterView parent, View v, int position, long id) {
// Do something in response to the click
}
};
listView.setOnItemClickListener(mMessageClickedHandler); public class ListViewLoader extends ListActivity
implements LoaderManager.LoaderCallbacks<Cursor> {
// This is the Adapter being used to display the list's data
SimpleCursorAdapter mAdapter;
// These are the Contacts rows that we will retrieve
static final String[] PROJECTION = new String[] {ContactsContract.Data._ID,
ContactsContract.Data.DISPLAY_NAME};
// This is the select criteria
static final String SELECTION = "((" +
ContactsContract.Data.DISPLAY_NAME + " NOTNULL) AND (" +
ContactsContract.Data.DISPLAY_NAME + " != '' ))";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a progress bar to display while the list loads
ProgressBar progressBar = new ProgressBar(this);
progressBar.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT, Gravity.CENTER));
progressBar.setIndeterminate(true);
getListView().setEmptyView(progressBar);
// Must add the progress bar to the root of the layout
ViewGroup root = (ViewGroup) findViewById(android.R.id.content);
root.addView(progressBar);
// For the cursor adapter, specify which columns go into which views
String[] fromColumns = {ContactsContract.Data.DISPLAY_NAME};
int[] toViews = {android.R.id.text1}; // The TextView in simple_list_item_1
// Create an empty adapter we will use to display the loaded data.
// We pass null for the cursor, then update it in onLoadFinished()
mAdapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_1, null,
fromColumns, toViews, 0);
setListAdapter(mAdapter);
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);
}
// Called when a new Loader needs to be created
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
// Now create and return a CursorLoader that will take care of
// creating a Cursor for the data being displayed.
return new CursorLoader(this, ContactsContract.Data.CONTENT_URI,
PROJECTION, SELECTION, null, null);
}
// Called when a previously created loader has finished loading
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Swap the new cursor in. (The framework will take care of closing the
// old cursor once we return.)
mAdapter.swapCursor(data);
}
// Called when a previously created loader is reset, making the data unavailable
public void onLoaderReset(Loader<Cursor> loader) {
// This is called when the last Cursor provided to onLoadFinished()
// above is about to be closed. We need to make sure we are no
// longer using it.
mAdapter.swapCursor(null);
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// Do something when a list item is clicked
}
} 5.ListView动态获取网络数据方式【见下一节文章】
6.ExpandableListView相关类和知识点
public class ExpandableListView extends ListView：ListView的子类，android.widget.ExpandableListView
两级列表，分为组和组中Items，使用ExpandableListAdapter接口提供数据；
重要的接口：
ExpandableListView.OnChildClickListener 、ExpandableListView.OnGroupClickListener
ExpandableListView.OnGroupCollapseListener 、ExpandableListView.OnGroupExpandListener
重要的XML属性：
android:childDivider：color或者Drawable资源文件，子项目的分隔符
android:childIndicator ：状态列表的Drawable资源文件，用于定义子项目各种状态对应的效果
android:groupIndicator
重要方法：
ExpandableListAdapter getExpandableListAdapter()：
boolean collapseGroup(int groupPos)
boolean expandGroup(int groupPos)
boolean expandGroup(int groupPos, boolean animate)
long getSelectedPosition()：获取选择Group或者child的位置，该位置是打包以后的；综合的
long getSelectedId ()：获取已经选择的Group或者child的id，如果没选择，则返回-1；
static int getPackedPositionChild(long packedPosition)
public boolean setSelectedChild (int groupPosition, int childPosition, boolean shouldExpandGroup)
public void setSelectedGroup (int groupPosition)
相关的类：public interface ExpandableListAdapter：按Group组织数据，为可展开类别提供数据；
间接子类：
BaseExpandableListAdapter, CursorTreeAdapter, ResourceCursorTreeAdapter,
SimpleCursorTreeAdapter, SimpleExpandableListAdapter
SimpleExpandableListAdapter：
注意groupTo和ChildTo所对应的视图都是TextView才行（ImageView不行，其它类型的视图，需要重写getGroupView和getChildView方法；）；
简单的Adapter映射静态数据到group和child view。
构造器：9个参数
SimpleExpandableListAdapter(Context context, List<? extends Map<String, ?>> groupData, int groupLayout,
String[] groupFrom, int[] groupTo, List<? extends List<? extends Map<String, ?>>> childData,
int childLayout, String[] childFrom, int[] childTo)groupData:Map的列表，列表中的每一项代表一组所有属性数据，Map包含组的数据，至少包含groupFrom所有的条目，例如每个Group需要一个textView和ImageView，那么可以map1.put("text","xxxx"); map1.put("image", "ddd")作为第一组的group Item；
groupLayout:Group视图的布局文件id，至少包含groupTo中的所有组件id
groupFrom：一组keys（用于获取每个组的数据，因为一个组项view可能需要多个数据），用于从Maps获取关联的该组view的数据
groupTo：一组view id，用于对应展示groupFrom中列数据
childData：Map对象列表的列表，外围的列表代表每个组，里面的列表代表每一组里面的项所有属性数据；
其它参数类似；
SimpleExpandableListAdapter(Context context, List<? extends Map<String, ?>> groupData,
int expandedGroupLayout, int collapsedGroupLayout, String[] groupFrom,
int[] groupTo, List<? extends List<? extends Map<String, ?>>> childData,
int childLayout, String[] childFrom, int[] childTo)
SimpleExpandableListAdapter(Context context, List<? extends Map<String, ?>> groupData,
int expandedGroupLayout, int collapsedGroupLayout, String[] groupFrom, int[] groupTo,
List<? extends List<? extends Map<String, ?>>> childData, int childLayout,
int lastChildLayout, String[] childFrom, int[] childTo)SimpleCursorTreeAdapter：
SimpleCursorTreeAdapter(Context context, Cursor cursor, int collapsedGroupLayout,
int expandedGroupLayout, String[] groupFrom, int[] groupTo, int childLayout,
int lastChildLayout, String[] childFrom, int[] childTo)
SimpleCursorTreeAdapter(Context context, Cursor cursor, int collapsedGroupLayout,
int expandedGroupLayout, String[] groupFrom, int[] groupTo, int childLayout,
String[] childFrom, int[] childTo)
SimpleCursorTreeAdapter(Context context, Cursor cursor, int groupLayout, String[] groupFrom,
int[] groupTo, int childLayout, String[] childFrom, int[] childTo)7.ExpandableListView的使用实例
参见上篇文章：http://blog.youkuaiyun.com/meplusplus/article/details/26622261
8.如何定制自己的ExpandableListAdapter
主要是学习系统的源码实现，继承已有的ListAdapter，以下是系统SimpleExpandableListAdapter的源码实现，我们可以继承然后重写getChildView和getGroupView方法；
package android.widget;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.view.LayoutInflater;
import java.util.List;
import java.util.Map;
/**
* An easy adapter to map static data to group and child views defined in an XML
* file. You can separately specify the data backing the group as a List of
* Maps. Each entry in the ArrayList corresponds to one group in the expandable
* list. The Maps contain the data for each row. You also specify an XML file
* that defines the views used to display a group, and a mapping from keys in
* the Map to specific views. This process is similar for a child, except it is
* one-level deeper so the data backing is specified as a List<List<Map>>,
* where the first List corresponds to the group of the child, the second List
* corresponds to the position of the child within the group, and finally the
* Map holds the data for that particular child.
*/
public class SimpleExpandableListAdapter extends BaseExpandableListAdapter {
private List<? extends Map<String, ?>> mGroupData;
private int mExpandedGroupLayout;
private int mCollapsedGroupLayout;
private String[] mGroupFrom;
private int[] mGroupTo;
private List<? extends List<? extends Map<String, ?>>> mChildData;
private int mChildLayout;
private int mLastChildLayout;
private String[] mChildFrom;
private int[] mChildTo;
private LayoutInflater mInflater;
/**
* Constructor
*
* @param context The context where the {@link ExpandableListView}
* associated with this {@link SimpleExpandableListAdapter} is
* running
* @param groupData A List of Maps. Each entry in the List corresponds to
* one group in the list. The Maps contain the data for each
* group, and should include all the entries specified in
* "groupFrom"
* @param groupFrom A list of keys that will be fetched from the Map
* associated with each group.
* @param groupTo The group views that should display column in the
* "groupFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the groupFrom parameter.
* @param groupLayout resource identifier of a view layout that defines the
* views for a group. The layout file should include at least
* those named views defined in "groupTo"
* @param childData A List of List of Maps. Each entry in the outer List
* corresponds to a group (index by group position), each entry
* in the inner List corresponds to a child within the group
* (index by child position), and the Map corresponds to the data
* for a child (index by values in the childFrom array). The Map
* contains the data for each child, and should include all the
* entries specified in "childFrom"
* @param childFrom A list of keys that will be fetched from the Map
* associated with each child.
* @param childTo The child views that should display column in the
* "childFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the childFrom parameter.
* @param childLayout resource identifier of a view layout that defines the
* views for a child. The layout file should include at least
* those named views defined in "childTo"
*/
public SimpleExpandableListAdapter(Context context,
List<? extends Map<String, ?>> groupData, int groupLayout,
String[] groupFrom, int[] groupTo,
List<? extends List<? extends Map<String, ?>>> childData,
int childLayout, String[] childFrom, int[] childTo) {
this(context, groupData, groupLayout, groupLayout, groupFrom, groupTo, childData,
childLayout, childLayout, childFrom, childTo);
}
/**
* Constructor
*
* @param context The context where the {@link ExpandableListView}
* associated with this {@link SimpleExpandableListAdapter} is
* running
* @param groupData A List of Maps. Each entry in the List corresponds to
* one group in the list. The Maps contain the data for each
* group, and should include all the entries specified in
* "groupFrom"
* @param groupFrom A list of keys that will be fetched from the Map
* associated with each group.
* @param groupTo The group views that should display column in the
* "groupFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the groupFrom parameter.
* @param expandedGroupLayout resource identifier of a view layout that
* defines the views for an expanded group. The layout file
* should include at least those named views defined in "groupTo"
* @param collapsedGroupLayout resource identifier of a view layout that
* defines the views for a collapsed group. The layout file
* should include at least those named views defined in "groupTo"
* @param childData A List of List of Maps. Each entry in the outer List
* corresponds to a group (index by group position), each entry
* in the inner List corresponds to a child within the group
* (index by child position), and the Map corresponds to the data
* for a child (index by values in the childFrom array). The Map
* contains the data for each child, and should include all the
* entries specified in "childFrom"
* @param childFrom A list of keys that will be fetched from the Map
* associated with each child.
* @param childTo The child views that should display column in the
* "childFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the childFrom parameter.
* @param childLayout resource identifier of a view layout that defines the
* views for a child. The layout file should include at least
* those named views defined in "childTo"
*/
public SimpleExpandableListAdapter(Context context,
List<? extends Map<String, ?>> groupData, int expandedGroupLayout,
int collapsedGroupLayout, String[] groupFrom, int[] groupTo,
List<? extends List<? extends Map<String, ?>>> childData,
int childLayout, String[] childFrom, int[] childTo) {
this(context, groupData, expandedGroupLayout, collapsedGroupLayout,
groupFrom, groupTo, childData, childLayout, childLayout,
childFrom, childTo);
}
/**
* Constructor
*
* @param context The context where the {@link ExpandableListView}
* associated with this {@link SimpleExpandableListAdapter} is
* running
* @param groupData A List of Maps. Each entry in the List corresponds to
* one group in the list. The Maps contain the data for each
* group, and should include all the entries specified in
* "groupFrom"
* @param groupFrom A list of keys that will be fetched from the Map
* associated with each group.
* @param groupTo The group views that should display column in the
* "groupFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the groupFrom parameter.
* @param expandedGroupLayout resource identifier of a view layout that
* defines the views for an expanded group. The layout file
* should include at least those named views defined in "groupTo"
* @param collapsedGroupLayout resource identifier of a view layout that
* defines the views for a collapsed group. The layout file
* should include at least those named views defined in "groupTo"
* @param childData A List of List of Maps. Each entry in the outer List
* corresponds to a group (index by group position), each entry
* in the inner List corresponds to a child within the group
* (index by child position), and the Map corresponds to the data
* for a child (index by values in the childFrom array). The Map
* contains the data for each child, and should include all the
* entries specified in "childFrom"
* @param childFrom A list of keys that will be fetched from the Map
* associated with each child.
* @param childTo The child views that should display column in the
* "childFrom" parameter. These should all be TextViews. The
* first N views in this list are given the values of the first N
* columns in the childFrom parameter.
* @param childLayout resource identifier of a view layout that defines the
* views for a child (unless it is the last child within a group,
* in which case the lastChildLayout is used). The layout file
* should include at least those named views defined in "childTo"
* @param lastChildLayout resource identifier of a view layout that defines
* the views for the last child within each group. The layout
* file should include at least those named views defined in
* "childTo"
*/
public SimpleExpandableListAdapter(Context context,
List<? extends Map<String, ?>> groupData, int expandedGroupLayout,
int collapsedGroupLayout, String[] groupFrom, int[] groupTo,
List<? extends List<? extends Map<String, ?>>> childData,
int childLayout, int lastChildLayout, String[] childFrom,
int[] childTo) {
mGroupData = groupData;
mExpandedGroupLayout = expandedGroupLayout;
mCollapsedGroupLayout = collapsedGroupLayout;
mGroupFrom = groupFrom;
mGroupTo = groupTo;
mChildData = childData;
mChildLayout = childLayout;
mLastChildLayout = lastChildLayout;
mChildFrom = childFrom;
mChildTo = childTo;
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public Object getChild(int groupPosition, int childPosition) {
return mChildData.get(groupPosition).get(childPosition);
}
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
View convertView, ViewGroup parent) {
View v;
if (convertView == null) {
v = newChildView(isLastChild, parent);
} else {
v = convertView;
}
bindView(v, mChildData.get(groupPosition).get(childPosition), mChildFrom, mChildTo);
return v;
}
/**
* Instantiates a new View for a child.
* @param isLastChild Whether the child is the last child within its group.
* @param parent The eventual parent of this new View.
* @return A new child View
*/
public View newChildView(boolean isLastChild, ViewGroup parent) {
return mInflater.inflate((isLastChild) ? mLastChildLayout : mChildLayout, parent, false);
}
private void bindView(View view, Map<String, ?> data, String[] from, int[] to) {
int len = to.length;
for (int i = 0; i < len; i++) {
TextView v = (TextView)view.findViewById(to[i]);
if (v != null) {
v.setText((String)data.get(from[i]));
}
}
}
public int getChildrenCount(int groupPosition) {
return mChildData.get(groupPosition).size();
}
public Object getGroup(int groupPosition) {
return mGroupData.get(groupPosition);
}
public int getGroupCount() {
return mGroupData.size();
}
public long getGroupId(int groupPosition) {
return groupPosition;
}
public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
ViewGroup parent) {
View v;
if (convertView == null) {
v = newGroupView(isExpanded, parent);
} else {
v = convertView;
}
bindView(v, mGroupData.get(groupPosition), mGroupFrom, mGroupTo);
return v;
}
/**
* Instantiates a new View for a group.
* @param isExpanded Whether the group is currently expanded.
* @param parent The eventual parent of this new View.
* @return A new group View
*/
public View newGroupView(boolean isExpanded, ViewGroup parent) {
return mInflater.inflate((isExpanded) ? mExpandedGroupLayout : mCollapsedGroupLayout,
parent, false);
}
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
public boolean hasStableIds() {
return true;
}
}
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