ListView分组实现方案(一)

分组的效果如下表格item列所示：

listView分组思路：在item.xml配置文件里面定义一个显示组名的TextView,该TextView只在当前分组的第一个时显示，其它的默认不显示(即View.GONE);

上面其余列的说明：

position列：对应getView方法里面的position参数；

groupIndex:当然position对应的item属于第几个分组，或者说当前分组的索引号。

group_position:当前分组组名所在的item在listView中所处的位置position，比如分组A在listView中的position位置为0，分组B在listView中对应的position为4

item.xml类似如下效果：

//上下布局的linearLayout

   //用来显示组名比如A
   
   //用来显示item的具体信息比如a1
   

具体实现思路以及伪代码(getView里面进行处理判断：

1.判断当前position对应的item属于哪一个或者第几个分组；并获取该分组的索引groupIndex

2.根据groupIndex来获取group_position的值，如果group_position==position那么就让group_name对应的textView 显示否则设置为View.GONE;

综上所述整体上getView的伪代码如下：

假设用一个String[]  group_names = {"A","B","C",...}来保存分组的名称

int[]  group_positions = {0,4}用来保存当前分组在listView中的位置

Int groupIndex = getGroupIndex(position);
Int group_position = getGroup_Position(groupIndex);
If(group_position==position){
  group_name.setVisiable(true);
  group_name.setText(group_names(groupIndex));
}else{
 group_name.setVisiable(false);
}

获取当前item属于哪一个分组getGroupIndex(position)的伪代码如下

//获取当前position 对应的item
Item item = getItem(position);
//获取groupIndex
Int groupIndex = Arrays.binarySearch(group_names,item.getXXX())
return groupIndex>=0? index:-index-2;

item.getXXX()是获取item中显示字符串第一个首字母的大写字母

//那么获取当前分组在ListView中对应位置的getGroupPosition(groupIndex)的代码就如下所 
return group_positions.get(groupIndex)

关于ListView分组，Android提供了SectionIndexer接口，该接口提供了三个方法，实现分组的思路大体上跟上面讲的差不多，就不在赘述(吐槽，个人感觉SectionIndexer的名字不如GroupIndexer好)

下面贴上自己的测试代码：

activity_main.xml

item.xml：

public class MainActivity extends Activity {

    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        ListView list = (ListView) findViewById(R.id.myListView);  
        ArrayList stringList = InitListData();  
        MyAdapter adapter = new MyAdapter(this, stringList);  
        list.setAdapter(adapter);  
       
    }  
    private ArrayList InitListData() {  
        ArrayList stringList = new ArrayList();  
        stringList.add("aenegli");  
        stringList.add("abddaf");  
        stringList.add("are");  
        stringList.add("care");  
        stringList.add("ahow");  
        stringList.add("abide");       
        stringList.add("bandidate");  
        stringList.add("bapture");    
        stringList.add("catch");  
        stringList.add("call");  
        stringList.add("abuse");  
        stringList.add("cow");  
        //排个序
        Collections.sort(stringList);
        return stringList;  
    }  
}

public class MyAdapter extends BaseAdapter {

	    //分组名
	    private char groupNames[] = {
	    		'A','B','C'
	    };
	    
	    private List groupPositions;
	   
	    private List stringArray;  
	   
	    //初始化groupPositions
	    private void initGroupPositions(){
	    	groupPositions = new ArrayList();
	    	for (int i = 0; i < stringArray.size(); i++) {
				if(i==0){//第一条数据			
					groupPositions.add(0);
					continue;
				}
				
				if(i != groupPositions.size()){
					String currentStr = stringArray.get(i);
					String preStr = stringArray.get(i-1);
					char firstCharOfCurrentStr = currentStr.charAt(0);
					char firstCharOfPreStr = preStr.charAt(0);
					if(firstCharOfCurrentStr!=firstCharOfPreStr){
						groupPositions.add(i);
					}
				}
			}
	    }
	    private Context context;  
	    public MyAdapter(Context context, ArrayList arr) {  
	        stringArray = arr;  
	        this.context = context;  
	        initGroupPositions();
	       Log.e("groupPositions== ",groupPositions.size()+""); 
	    }  
	    public int getCount() {  
	        return stringArray.size();  
	    }  
	    public String getItem(int position) {  
	        return stringArray.get(position);  
	    }  
	    public long getItemId(int position) {  
	        return position;  
	    }  
	    public View getView(int position, View view, ViewGroup parent) {  
	    	LayoutInflater inflate = ((Activity) context).getLayoutInflater();    
	        view = (View) inflate.inflate(R.layout.item, null);  
	        TextView groupNameView = (TextView) view.findViewById(R.id.group_name);  
	        String itemStr = stringArray.get(position);  
	        //分组处理
	        int groupIndex = getGroupIndex(position);
	        int groupPosition = getGroupPosition(groupIndex);
	        if(position==groupPosition){
	        	groupNameView.setText(groupNames[groupIndex]+"");
	        	groupNameView.setVisibility(View.VISIBLE);
	        }else{
	        	groupNameView.setVisibility(View.GONE);
	        }
	        TextView textView = (TextView) view.findViewById(R.id.item_info);  
	        textView.setText(itemStr);  
	        return view;  
	    }  
	  
	    //根据position获取当前item属于第几个group,也就是获取group的索引
	    public int getGroupIndex(int position) {  
	    	String itemStr = getItem(position);
	    	char firstChar = itemStr.toUpperCase().charAt(0);
	    	
	    	int groupIndex = Arrays.binarySearch(groupNames, firstChar);
	    	Log.e("firstChar--groupIndex",firstChar+"---"+groupIndex);
	        return groupIndex>=0?groupIndex:-groupIndex-2;  
	    }  
	   
	    //根据groupIndex来获取当前分组对应于ListView中的position
	    public int getGroupPosition(int groupIndex){
	    	return groupPositions.get(groupIndex);
	    }
}