在Android某些开发需求当中,有时候需要在listveiw中加入checkbox实现单选,多选操作。表面上看上去只是改变checkbox那么简单,然而实际开发中,实现起来并不是那么得心应手。尤其当listview比较多(比如屏幕最多只能显示10个item,但总共有12个item,也就是说listview的item数大于屏幕能够显示的item数)滑动屏幕的时候,由于适配器中getview()会重复使用被移除屏幕的item,所以会造成checkbox选择状态不正常的现象。自己在开发中碰到这样的问题很是苦恼,查了下资料,发现网上很少没有针对这类批量操作并没有一个完整的例子。搜了很多篇帖子才完美的实现这一常用的操作。所以在这里把这个Demo贴出来,供大家参考,希望能对大家有所帮助。
主界面的布局main.xml 这个就不多说什么
<LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="wrap_content" > <TextView android:layout_width="fill_parent" android:layout_height="100dip" android:text="原创:Simtice QQ:512375320" android:layout_marginLeft="10dip" /> </LinearLayout><?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="wrap_content" android:orientation="vertical" > <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="wrap_content" > <TextView android:id="@+id/tv" android:layout_width="fill_parent" android:layout_height="50dip" android:textColor="#FCFCFC" android:textSize="11pt" android:gravity="center_vertical" android:layout_marginLeft="10dip" /> <ListView android:id="@+id/lv" android:layout_width="fill_parent" android:layout_height="381dip" android:cacheColorHint ="#00000000" ></ListView> </LinearLayout> <RelativeLayout android:layout_width="fill_parent" android:layout_height="53dip" android:orientation="horizontal" > <Button android:id="@+id/selectall" android:layout_width="80dip" android:layout_height="50dip" android:layout_marginLeft="20dip" android:text="全选" android:gravity="center" /> <Button android:id="@+id/inverseselect" android:layout_width="80dip" android:layout_height="50dip" android:layout_marginLeft="118dip" android:text="反选" android:gravity="center" /> <Button android:id="@+id/cancel" android:layout_width="80dip" android:layout_height="50dip" android:layout_marginLeft="213dip" android:text="取消已选" android:gravity="center" /> </RelativeLayout> <LinearLayout android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="wrap_content" > <TextView android:layout_width="fill_parent" android:layout_height="100dip" android:text="原创:Simtice QQ:512375320" android:layout_marginLeft="10dip" /> </LinearLayout> </LinearLayout>
ListView每个item的布局,listviewitem.xml:
这里需要注意的是,由于checkbox的点击事件优先级比listview的高,所以要添加android:focusable="false"属性,使得checkbox初始的时候没有获取焦点。
另外这里是点击ListView的item控制checkbox的状态改变,也就是让item接收clik事件,所以需要加上android:focusableInTouchMode="false"这一属性。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="55dip" android:orientation="horizontal" android:layout_marginTop="20dip" > <TextView android:id="@+id/item_tv" android:layout_width="267dip" android:layout_height="40dip" android:textSize="10pt" android:gravity="center_vertical" android:layout_marginLeft="10dip" /> <CheckBox android:id="@+id/item_cb" android:layout_width="wrap_content" android:layout_height="wrap_content" android:focusable="false" android:focusableInTouchMode="false" android:clickable="false" android:layout_toRightOf="@id/item_tv" android:layout_alignParentTop="true" android:layout_marginRight="5dip" /> </RelativeLayout
ViewHolder类
package simtice.test.listview.viewholder; import android.widget.CheckBox; import android.widget.TextView; public class ViewHolder { public TextView tv = null; public CheckBox cb = null; }
为listview自定义适配器,该类为主Activity类MainActivity.java的内部类
class MyAdapter extends BaseAdapter { @Override public int getCount() { return list.size(); } @Override public Item getItem(int arg0) { return list.get(arg0); } @Override public long getItemId(int arg0) { return arg0; } @Override public View getView(int position, View view, ViewGroup arg2) { System.out.println("getView " + position + " " + view); ViewHolder holder; if (view == null || (holder = (ViewHolder) view.getTag()) == null) { view = View.inflate(MainActivity.this, R.layout.listviewitem, null); holder = new ViewHolder(); holder.tv = (TextView) view.findViewById(R.id.item_tv); holder.cb = (CheckBox) view.findViewById(R.id.item_cb); view.setTag(holder); } Item item = getItem(position); holder.tv.setText(item.name); holder.cb.setChecked(item.status); return view; }
最后,最重要的就是MainActivity.java中一些事件响应的处理
public class MainActivity extends Activity implements OnClickListener { TextView tv = null; ListView lv = null; String name[] = { "G1", "G2", "G3", "G4", "G5", "G6", "G7", "G8", "G9", "G10", "G11", "G12", "G13", "G14" }; private List<Item> list; private List<String> data; private MyAdapter adapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); tv = (TextView) this.findViewById(R.id.tv); lv = (ListView) this.findViewById(R.id.lv); this.findViewById(R.id.selectall).setOnClickListener(this); this.findViewById(R.id.inverseselect).setOnClickListener(this); this.findViewById(R.id.cancel).setOnClickListener(this); lv.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { Item item = list.get(arg2); item.status = !item.status;// 取反 initAdapter(); } }); init(); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.selectall: int size1 = list.size(); for (int i = 0; i < size1; i++) { list.get(i).status = true; } break; case R.id.inverseselect: int size2 = list.size(); for (int i = 0; i < size2; i++) { Item item = list.get(i); item.status = !item.status;// 取反 } break; case R.id.cancel: int size3 = list.size(); for (int i = 0; i < size3; i++) { list.get(i).status = false; } break; } initAdapter(); } // 数据初始化 private void init() { if (list == null) list = new ArrayList<Item>(); else list.clear(); if (data == null) data = new ArrayList<String>(); for (String s : name) { list.add(new Item(s, false)); } initAdapter(); } // 刷新适配器 public void initAdapter() { if (adapter == null) { adapter = new MyAdapter(); lv.setAdapter(adapter); } else { adapter.notifyDataSetChanged(); } int size = list.size(); data.clear(); for (int i = 0; i < size; i++) { if (list.get(i).status) /*这里可以处理checkbox为true时的事件*/ data.add(name[i]); else /*为false时的事件*/ data.remove(name[i]); } tv.setText("已选中 " + data.size() + " 项"); } // 为listview自定义适配器内部类 class MyAdapter extends BaseAdapter { ... } class Item { public String name; public boolean status = false; public Item(String name, boolean b) { this.name = name; this.status = b; } }
我选择了G2、G3、G11三项,现在屏幕滑动到底部,看以看到状态保存的很好,TextView显示已选中3项。全选、反选、取消已选功能正常,多选操作完美解决!
源码:http://www.eoeandroid.com/thread-152037-1-1.html