android 的listview 内部item的布局包含checkbox控件时,会遇到常见的问题:1.checkbox无法选择;2.选择的checkbox后滑动listview内容时会checkbox选择的值会刷新成原来状态值(即没选中);3.选择listview所有checkbox值之后,只能获取当前可见的checkbox的值,向后滑动选择的值无法获取。
解决以上问题可以采取以下方法:
1.设置checkbox的属性值为:android:focusable=”false” ,防止焦点独占,解决checkbox无法选择的问题。
2.重写Adapter,重写getView方法;
3.重写Adapter的getView方法时,为每个checkbox添加事件响应并记录选择状态,通过获取获取状态记录值获取所有选择的checkbox值。
需要注意的是第三点,在重写getView方法时,不要判断convertView == null,如果判断convertView == null再实例化相关的控件,则刷新的是局部控件(这个尚需要观点有待论证)。
以下的程序代码就是围绕以上三点编写的例子
图-1 获取listview checkbox 所有选择的值
ListView_CheckBoxActivity.java实现界面及其事件功能,通过点击Button按钮获取选择的checkbox值,并在Toast控件中显示,如图-1。
1. ListView_CheckBoxActivity.java
package com.checkbox.main;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class ListView_CheckBoxActivity extends Activity {
//适配器
CheckboxAdapter listItemAdapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//按钮及事件响应
Button getValue=(Button)findViewById(R.id.get_value);
getValue.setOnClickListener(listener);
//listview
ListView list = (ListView) findViewById(R.id.list);
//存储数据的数组列表
ArrayList<HashMap<String, Object>> listData=new ArrayList<HashMap<String,Object>>();
String []name={"William","Charles","Linng","Json","Bob","Carli","William","Charles","Linng",
"Json","Bob","Carli"};
String []id={"1","2","3","4","5","6","7","8","9","10","11","12"};
for(int i=0;i<12;i++){
HashMap<String, Object> map=new HashMap<String, Object>();
map.put("friend_image", R.drawable.icon);
map.put("friend_username", name[i]);
map.put("friend_id", id[i]);
map.put("selected", false);
//添加数据
listData.add(map);
}
//适配器
listItemAdapter = new CheckboxAdapter(this, listData);
list.setAdapter(listItemAdapter);
}
//事件响应
OnClickListener listener=new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
HashMap<Integer, Boolean> state =listItemAdapter.state;
String options="选择的项是:";
for(int j=0;j<listItemAdapter.getCount();j++){
System.out.println("state.get("+j+")=="+state.get(j));
if(state.get(j)!=null){
@SuppressWarnings("unchecked")
HashMap<String, Object> map=(HashMap<String, Object>) listItemAdapter.getItem(j);
String username=map.get("friend_username").toString();
String id=map.get("friend_id").toString();
options+="\n"+id+"."+username;
}
}
//显示选择内容
Toast.makeText(getApplicationContext(), options, Toast.LENGTH_LONG).show();
}
};
}
复制代码 CheckboxAdapter 继承BaseAdapter并重写相关函数,重写getView时,为每个checkbox添加事件响应并通过HashMap记录选择状态,以便获取相应的checkbox值。
2.CheckboxAdapter .java
package com.checkbox.main;
import java.util.ArrayList;
import java.util.HashMap;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.ImageView;
import android.widget.TextView;
public class CheckboxAdapter extends BaseAdapter {
Context context;
ArrayList<HashMap<String, Object>> listData;
//记录checkbox的状态
HashMap<Integer, Boolean> state = new HashMap<Integer, Boolean>();
//构造函数
public CheckboxAdapter(Context context,ArrayList<HashMap<String,Object>> listData) {
this.context = context;
this.listData = listData;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return listData.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return listData.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
// 重写View
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater mInflater = LayoutInflater.from(context);
convertView = mInflater.inflate(R.layout.item, null);
ImageView image = (ImageView) convertView.findViewById(R.id.friend_image);
image.setBackgroundResource((Integer) listData.get(position).get("friend_image"));
TextView username = (TextView) convertView.findViewById(R.id.friend_username);
username.setText((String) listData.get(position).get("friend_username"));
TextView id = (TextView) convertView.findViewById(R.id.friend_id);
id.setText((String) listData.get(position).get("friend_id"));
CheckBox check = (CheckBox) convertView.findViewById(R.id.selected);
check.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
// TODO Auto-generated method stub
if (isChecked) {
state.put(position, isChecked);
} else {
state.remove(position);
}
}
});
check.setChecked((state.get(position) == null ? false : true));
return convertView;
}
}
复制代码 加载的布局文件
3.main.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" >
<Button android:id="@+id/get_value"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="获取Checkbox值" />
<ListView android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
复制代码 listview item内部的布局文件
4.item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/RelativeLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingBottom="4dip"
android:paddingRight="12dip" >
<ImageView android:id="@+id/friend_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingTop="6dip"
android:paddingLeft="2dip"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true" />
<TextView android:id="@+id/friend_username"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="18dip"
android:textColor="#ccc"
android:paddingTop="6dip"
android:paddingRight="2dip"
android:layout_toRightOf="@id/friend_image" />
<TextView android:id="@+id/friend_id"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/friend_username"
android:layout_marginRight="36dip"
android:paddingRight="2dip"
android:layout_toRightOf="@id/friend_image"
android:textColor="#fff"
android:maxLines="2" />
<CheckBox android:id="@+id/selected"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="36dip"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:focusable="false" />
</RelativeLayout>
复制代码
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