ListView Item选择问题解决之道
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在Android应用开发中，很多时候都会遇到这样的需求，一个listView，含有N项，当点击某项时，该项展开，显示该项中隐藏的某些控件，再点击，该项收回，重新隐藏部分控件，当一项打开状态，点击另一项，另一项展开，该项关闭。（说的有点绕，看下图）
??????? 在去年的时候，自己的一篇文章（http://blog.csdn.net/aomandeshangxiao/article/details/6643831），里面有Item的选择问题，用的方法比较笨，要遍历一遍，把所有的item全部都设置一下，应该是很浪费资源的。还有一个问题就是，当listview的item多于一个屏幕的时候，会出现重复选择问题，就是当你选中一项滑动的时候，可能会发现滑动后出现的某项也是在选中状态，这个问题令人十分抓狂。见网上有个方法是：在adapter的getView里面不使用convertview。每一个view都是重新创建一个。能够解决问题，但是还是有点浪费资源。
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??????? 先看下效果图：第二项被选中
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第四项被选中：
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??????? 这个方法也是在他人的帮助下，努力得来，分享一下!
[java]?
public class ListViewTestActivity extends Activity implements OnItemClickListener{?
??? private ListView mListView;?
??? private ListAdapter mAdapter;?
??? @Override?
??? public void onCreate(Bundle savedInstanceState) {?
??????? super.onCreate(savedInstanceState);?
??????? setContentView(R.layout.main);?
?????????
??????? mListView = (ListView)findViewById(R.id.list);?
??????? mAdapter = new? ListAdapter(this);?
??????? mListView.setAdapter(mAdapter);?
??????? mListView.setOnItemClickListener(this);?
??? }?
?????
??? @Override?
??? public void onItemClick(AdapterView<?> parent, View view, int position, long id) {?
??????? mAdapter.changeImageVisable(view, position);?
??? }?
}?
??????? 这里应该注意到与平常的不同，onItemClick方法里面调用了自定义ListAdapter里面的自定义changeImageViewVisable方法。
看ListAdapter：
[html]?
public class ListAdapter extends BaseAdapter {?
??? private Context mContext;?
??? private View mLastView;?
??? private int mLastPosition;?
?????
??? public ListAdapter(Context context) {?
??????? this.mContext = context;?
??? }?
?
??? @Override?
??? public int getCount() {?
??????? return 8;?
??? }?
?
??? @Override?
??? public Object getItem(int position) {?
??????? return null;?
??? }?
?
??? @Override?
??? public long getItemId(int position) {?
??????? return 0;?
??? }?
?
??? @Override?
??? public View getView(int position, View convertView, ViewGroup parent) {?
??????? Holder holder;?
??????? if(convertView == null ) {?
??????????? LayoutInflater inflater = LayoutInflater.from(mContext);?
??????????? convertView = inflater.inflate(R.layout.list_item, null);?
??????????? holder =new Holder();?
??????????? holder.textView = (TextView)convertView.findViewById(R.id.textView);?
??????????? holder.UEFAView = (ImageView)convertView.findViewById(R.id.image_uefa);?
??????????? holder.mascotView = (ImageView)convertView.findViewById(R.id.image_mascot);?
??????????? holder.hint = convertView.findViewById(R.id.hint_image);?
??????????? convertView.setTag(holder);?
??????? } else {?
??????????? holder = (Holder) convertView.getTag();?
??????? }?
??????? holder.textView.setText("Hello,It is " + position);?
??????? return convertView;?
??? }?
?????
??? class Holder {?
??????? TextView textView;?
??????? ImageView UEFAView;?
??????? ImageView mascotView;?
??????? View hint;?
??? }?
?????
??? public void changeImageVisable(View view,int position) {?
??????? if(mLastView != null && mLastPosition != position ) {?
??????????? Holder holder = (Holder) mLastView.getTag();?
??????????? switch(holder.hint.getVisibility()) {?
??????????? case View.VISIBLE:?
??????????????? holder.hint.setVisibility(View.GONE);?
??????????????? break;?
??????????? default :?
??????????????? break;?
??????????? }?
??????? }?
??????? mLastPosition = position;?
??????? mLastView = view;?
??????? Holder holder = (Holder) view.getTag();?
??????? switch(holder.hint.getVisibility()) {?
??????? case View.GONE:?
??????????? holder.hint.setVisibility(View.VISIBLE);?
??????????? break;?
??????? case View.VISIBLE:?
??????????? holder.hint.setVisibility(View.GONE);?
??????????? break;?
??????? }?
??? }?
?
}?
?????? 代码的最下端是changeImageVisable方法。（注意：在这个方法中，博客代码版本和提供下载代码版本中有细微差异，博客代码较下载代码性能更优，这也体现了Holder类的优越性，一定要好好用好Holder，应好好思考下，为什么这样写性能就更好些呢？欢迎留言讨论）。
??????? 布局文件：
main.xml：
[html]?
<?xml version="1.0" encoding="utf-8"?>?
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"?
??? android:layout_width="fill_parent"?
??? android:layout_height="fill_parent"?
??? android:orientation="vertical" >?
?
??? <TextView?
??????? android:layout_width="fill_parent"?
??????? android:layout_height="wrap_content"?
??????? android:text="ListView Test" />?
??? <ListView??
??????? android:id="@+id/list"?
??????? android:layout_width="wrap_content"?
??????? android:layout_height="fill_parent"?
??????? ></ListView>?
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</LinearLayout>?
list_item.xml：
[html]
<?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/textView"?
??????? android:layout_width="wrap_content"?
??????? android:layout_height="wrap_content"?
??????? android:text="Test"?
??????? android:textSize="20sp"?
??????? />?
??? <LinearLayout?
??????? android:id="@+id/hint_image"?
??????? android:layout_width="match_parent"?
??????? android:layout_height="wrap_content"?
??????? android:orientation="horizontal"?
??????? android:visibility="gone">?
??????? <ImageView??
??????????? android:id="@+id/image_uefa"?
??????????? android:layout_width="0dp"?
??????????? android:layout_height="60dp"?
??????????? android:layout_weight="1"?
??????????? android:src="@drawable/uefa"?
??????????? />?
??????? <ImageView??
??????????? android:id="@+id/image_mascot"?
??????????? android:layout_width="0dp"?
??????????? android:layout_height="60dp"?
??????????? android:layout_weight="1"?
??????????? android:src="@drawable/mascot"?
??????????? />?
?????????
??? </LinearLayout>?
?????
</LinearLayout>?
作者：aomandeshangxiao
