import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
public class TestLinkedHashMap {

  public static void main(String args[])
  {
   System.out.println("*************************LinkedHashMap*************");
   Map<Integer,String> map = new LinkedHashMap<Integer,String>();
   map.put(6, "apple");
   map.put(3, "banana");
   map.put(2,"pear");
  
   for (Iterator it =  map.keySet().iterator();it.hasNext();)
   {
    Object key = it.next();
    System.out.println( key+"="+ map.get(key));
   }
  
   System.out.println("*************************HashMap*************");
   Map<Integer,String> map1 = new  HashMap<Integer,String>();
   map1.put(6, "apple");
   map1.put(3, "banana");
   map1.put(2,"pear");
  
   for (Iterator it =  map1.keySet().iterator();it.hasNext();)
   {
    Object key = it.next();
    System.out.println( key+"="+ map1.get(key));
   }
  }
}

运行结果如下:

*************************LinkedHashMap*************
6=apple
3=banana
2=pear
*************************HashMap**************************
2=pear
6=apple
3=banana

分析:LinkedHashmap 的特点是put进去的对象位置未发生变化,而HashMap会发生变化.

LinkedHashMap使用双向链表保存了记录的插入顺序，在用Iterator遍历LinkedHashMap时，先得到的记录肯定是先插入的.HashMap里面存入的键值对在取出的时候是随机的,

也可以在构造时 用带参数，按照应用次数排序。在遍历的时候会比HashMap慢，不过有种情况例外，当HashMap容量很大，实际数据较少时，遍历起来可能会比 LinkedHashMap慢，因为LinkedHashMap的遍历速度只和实际数据有关，和容量无关，而HashMap的遍历速度和他的容量有关。

ExpandableListView / ExpandableListActivity

 二者关系 和 ListActivity / ListView 是一样的

[代码 步骤]

1. 定义含有ExpandableListView 的布局：main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/layout"
>
<ExpandableListView
android:id="@+id/expandList"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

2.  定义数据结构List<String>, List<List<String>> 分别用于存放 Group / Children 的String

List<String> group;
List<List<String>> child;

3. 初始化 List<String> List<List<String>>  并插入一些数据

public void initialData(){
group = new ArrayList<String>();
child = new ArrayList<List<String>>();
addInfo("griffinshi", new String[]{"13776117119","man","Jiangsu"});
addInfo("lancewu",new String[]{"1321134","man","Taiwan"});
addInfo("kandyli",new String[]{"12345"});
}
public void addInfo(String p,String[] c){
group.add(p);
List<String> item = new ArrayList<String>();
for(int i=0;i<c.length;i++){
item.add(c[i]);
}
child.add(item);
}

3. 定义BaseExpandableListAdapter 并与List<String> List<List<String>> 数据相适配

public class InfoDetailsAdapter extends BaseExpandableListAdapter {
Activity activity;
public InfoDetailsAdapter(Activity a){
activity = a;
}
//child method stub
@Override
public Object getChild(int groupPosition, int childPosition) {
// TODO Auto-generated method stub
return child.get(groupPosition).get(childPosition);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
// TODO Auto-generated method stub
return childPosition;
}
@Override
public int getChildrenCount(int groupPosition) {
// TODO Auto-generated method stub
return child.get(groupPosition).size();
}
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
String string = child.get(groupPosition).get(childPosition);
return getGenericView(string);
}
//group method stub
@Override
public Object getGroup(int groupPosition) {
// TODO Auto-generated method stub
return group.get(groupPosition);
}
@Override
public int getGroupCount() {
// TODO Auto-generated method stub
return group.size();
}
@Override
public long getGroupId(int groupPosition) {
// TODO Auto-generated method stub
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
String string = group.get(groupPosition);
return getGenericView(string);
}
//View stub to create Group/Children 's View
public TextView getGenericView(String s) {
// Layout parameters for the ExpandableListView
AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT, 64);
TextView text = new TextView(activity);
text.setLayoutParams(lp);
// Center the text vertically
text.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
// Set the text starting position
text.setPadding(36, 0, 0, 0);
text.setText(s);
return text;
}
@Override
public boolean hasStableIds() {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
// TODO Auto-generated method stub
return true;
}
}

4. emulator 运行截图：

5. 下面说一下 数据更新 问题 包括：添加数据 删除数据

* 定义添加数据界面：add.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="姓名:"
/>
<EditText
android:id="@+id/add_name"
android:layout_width="200dip"
android:layout_height="wrap_content"
/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="电话:"
/>
<EditText
android:id="@+id/add_phone"
android:layout_width="200dip"
android:layout_height="wrap_content"
/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="性别:"
/>
<EditText
android:id="@+id/add_sex"
android:layout_width="200dip"
android:layout_height="wrap_content"
/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="住址:"
/>
<EditText
android:id="@+id/add_home"
android:layout_width="200dip"
android:layout_height="wrap_content"
/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<Button
android:id="@+id/add_ok"
android:layout_width="90dip"
android:layout_height="wrap_content"
android:text="OK"
/>
<Button
android:id="@+id/add_no"
android:layout_width="90dip"
android:layout_height="wrap_content"
android:text="NO"
/>
</LinearLayout>
</LinearLayout>

* add.xml 里 View 的定义：

public void createDialogAdd(){
viewAdd = this.getLayoutInflater().inflate(R.layout.add, null);
dialogAdd = new Dialog(this);
dialogAdd.setContentView(viewAdd);
dialogAdd.setTitle("输入新成员信息");
add_name = (EditText)viewAdd.findViewById(R.id.add_name);
add_phone = (EditText)viewAdd.findViewById(R.id.add_phone);
add_sex = (EditText)viewAdd.findViewById(R.id.add_sex);
add_home = (EditText)viewAdd.findViewById(R.id.add_home);
add_ok = (Button)viewAdd.findViewById(R.id.add_ok);
add_no = (Button)viewAdd.findViewById(R.id.add_no);
add_ok.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
String[] data = {
add_phone.getText().toString(),
add_sex.getText().toString(),
add_home.getText().toString()
};
addInfo(add_name.getText().toString(),data);
dialogAdd.dismiss();
mAdapter.notifyDataSetChanged();
}
});
add_no.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
dialogAdd.dismiss();
}
});
}

* 运行截图：

* 定义删除数据界面：delete.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ID:"
/>
<EditText
android:id="@+id/delete_id"
android:layout_width="200dip"
android:layout_height="wrap_content"
/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<Button
android:id="@+id/delete_ok"
android:layout_width="90dip"
android:layout_height="wrap_content"
android:text="OK"
/>
<Button
android:id="@+id/delete_no"
android:layout_width="90dip"
android:layout_height="wrap_content"
android:text="NO"
/>
</LinearLayout>
</LinearLayout>

* delete.xml 里View 定义：

public void createDialogDelete(){
viewDelete = this.getLayoutInflater().inflate(R.layout.delete, null);
dialogDelete = new Dialog(this);
dialogDelete.setContentView(viewDelete);
dialogDelete.setTitle("删除指定成员");
delete_id = (EditText)viewDelete.findViewById(R.id.delete_id);
delete_ok = (Button)viewDelete.findViewById(R.id.delete_ok);
delete_no = (Button)viewDelete.findViewById(R.id.delete_no);
delete_ok.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
String id = delete_id.getText().toString();
if(! id.equals("")){
int i = Integer.parseInt(id);
group.remove(i);
child.remove(i);
dialogDelete.dismiss();
mAdapter.notifyDataSetChanged();
}
}
});
delete_no.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
// TODO Auto-generated method stub
dialogDelete.dismiss();
}
});
}

* 运行截图：

最后 说一下ExpandableListView的回调函数 用于监听那个id 被expand