本文主要是介绍Android 设计一个可单选,多选的ListView,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
首先:用系统自导item Layout
android 提供了相当多的UI,在android.widget 的UI组件库,下面就让我们看看他是ListView的用法吧。
下面的Demo 是一个
- /*
- * Copyright (C) 2008 Google Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- package com.example.android.apis.view;
- import android.app.ListActivity;
- import android.os.Bundle;
- import android.widget.ArrayAdapter;
- import android.widget.ListView;
- /**
- * This example shows how to use choice mode on a list. This list is
- * in CHOICE_MODE_SINGLE mode, which means the items behave like
- * checkboxes.
- */
- public class List10 extends ListActivity {
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setListAdapter(new ArrayAdapter<String>(this,
- android.R.layout.simple_list_item_single_choice, GENRES));
- final ListView listView = getListView();
- listView.setItemsCanFocus(false);
- listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
- }
- private static final String[] GENRES = new String[] {
- "Action", "Adventure", "Animation", "Children", "Comedy", "Documentary", "Drama",
- "Foreign", "History", "Independent", "Romance", "Sci-Fi", "Television", "Thriller"
- };
上面是一个单选的List Demo。
对于需要多选的话可以改变这些参数就OK了
- setListAdapter(new ArrayAdapter<String>(this,
- android.R.layout.simple_list_item_multiple_choice, GENRES));
- final ListView listView = getListView();
- listView.setItemsCanFocus(false);
- listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
很简单吧,Android的开发确实很不错。
会用到listview和checkbox配合来提供给用户一些选择操作,自定义Item layout
1.Item layout里放置一个CheckBox。
要注意的时候,这里我设置了CheckBox没有焦点,这样的话,无法单独点击checkbox,而是在点击listview的条目后,Checkbox会响应操作。
- <?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="horizontal" >
- <TextView
- android:id="@+id/item_tv"
- android:layout_width="0dp"
- android:layout_height="wrap_content"
- android:layout_weight="1"
- android:gravity="center_vertical"
- />
- <CheckBox
- android:id="@+id/item_cb"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:clickable="false"
- android:focusable="false"
- android:focusableInTouchMode="false"
- android:gravity="center_vertical"
- />
- </LinearLayout>
下面就写一个Adapter类,我们依然继承BaseAdapter类。这里我们使用一个HashMap<Integer,boolean>的键值来记录checkbox在对应位置的选中状况,这是本例的实现的基础。
- package com.notice.listcheck;
- 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.TextView;
- public class MyAdapter extends BaseAdapter{
- // 填充数据的list
- private ArrayList<String> list;
- // 用来控制CheckBox的选中状况
- private static HashMap<Integer,Boolean> isSelected;
- // 上下文
- private Context context;
- // 用来导入布局
- private LayoutInflater inflater = null;
- // 构造器
- public MyAdapter(ArrayList<String> list, Context context) {
- this.context = context;
- this.list = list;
- inflater = LayoutInflater.from(context);
- isSelected = new HashMap<Integer, Boolean>();
- // 初始化数据
- initDate();
- }
- // 初始化isSelected的数据
- private void initDate(){
- for(int i=0; i<list.size();i++) {
- getIsSelected().put(i,false);
- }
- }
- @Override
- public int getCount() {
- return list.size();
- }
- @Override
- public Object getItem(int position) {
- return list.get(position);
- }
- @Override
- public long getItemId(int position) {
- return position;
- }
- @Override
- public View getView(int position, View convertView, ViewGroup parent) {
- ViewHolder holder = null;
- if (convertView == null) {
- // 获得ViewHolder对象
- holder = new ViewHolder();
- // 导入布局并赋值给convertview
- convertView = inflater.inflate(R.layout.listviewitem, null);
- holder.tv = (TextView) convertView.findViewById(R.id.item_tv);
- holder.cb = (CheckBox) convertView.findViewById(R.id.item_cb);
- // 为view设置标签
- convertView.setTag(holder);
- } else {
- // 取出holder
- holder = (ViewHolder) convertView.getTag();
- }
- // 设置list中TextView的显示
- holder.tv.setText(list.get(position));
- // 根据isSelected来设置checkbox的选中状况
- holder.cb.setChecked(getIsSelected().get(position));
- return convertView;
- }
- public static HashMap<Integer,Boolean> getIsSelected() {
- return isSelected;
- }
- public static void setIsSelected(HashMap<Integer,Boolean> isSelected) {
- MyAdapter.isSelected = isSelected;
- }
- }
那么我们只需要在点击事件中,控制isSelected的键值即可控制对应位置checkbox的选中了。
在Activity中我们除了放置一个ListView外,还放置了三个按钮,分别实现全选,取消和反选。
看下Activity类的代码:
- package com.notice.listcheck;
- import java.util.ArrayList;
- import android.app.Activity;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.AdapterView;
- import android.widget.AdapterView.OnItemClickListener;
- import android.widget.Button;
- import android.widget.ListView;
- import android.widget.TextView;
- public class Ex_checkboxActivity extends Activity {
- private ListView lv;
- private MyAdapter mAdapter;
- private ArrayList<String> list;
- private Button bt_selectall;
- private Button bt_cancel;
- private Button bt_deselectall;
- private int checkNum; // 记录选中的条目数量
- private TextView tv_show;// 用于显示选中的条目数量
- /** Called when the activity is first created. */
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- /* 实例化各个控件 */
- lv = (ListView) findViewById(R.id.lv);
- bt_selectall = (Button) findViewById(R.id.bt_selectall);
- bt_cancel = (Button) findViewById(R.id.bt_cancelselectall);
- bt_deselectall = (Button) findViewById(R.id.bt_deselectall);
- tv_show = (TextView) findViewById(R.id.tv);
- list = new ArrayList<String>();
- // 为Adapter准备数据
- initDate();
- // 实例化自定义的MyAdapter
- mAdapter = new MyAdapter(list, this);
- // 绑定Adapter
- lv.setAdapter(mAdapter);
- // 全选按钮的回调接口
- bt_selectall.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- // 遍历list的长度,将MyAdapter中的map值全部设为true
- for (int i = 0; i < list.size(); i++) {
- MyAdapter.getIsSelected().put(i, true); //---------------------------------------------------------------
- }
- // 数量设为list的长度
- checkNum = list.size();
- // 刷新listview和TextView的显示
- dataChanged();
- }
- });
- // 取消按钮的回调接口
- bt_cancel.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- // 遍历list的长度,将已选的按钮设为未选
- for (int i = 0; i < list.size(); i++) {
- if (MyAdapter.getIsSelected().get(i)) {
- MyAdapter.getIsSelected().put(i, false); //---------------------------------------------------------------
- checkNum--;// 数量减1
- }
- }
- // 刷新listview和TextView的显示
- dataChanged();
- }
- });
- // 反选按钮的回调接口
- bt_deselectall.setOnClickListener(new OnClickListener() {
- @Override
- public void onClick(View v) {
- // 遍历list的长度,将已选的设为未选,未选的设为已选
- for (int i = 0; i < list.size(); i++) {
- if (MyAdapter.getIsSelected().get(i)) {
- MyAdapter.getIsSelected().put(i, false); //---------------------------------------------------------------
- checkNum--;
- } else {
- MyAdapter.getIsSelected().put(i, true); //---------------------------------------------------------------
- checkNum++;
- }
- }
- // 刷新listview和TextView的显示
- dataChanged();
- }
- });
- // 绑定listView的监听器
- lv.setOnItemClickListener(new OnItemClickListener() {
- @Override
- public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
- long arg3) {
- // 取得ViewHolder对象,这样就省去了通过层层的findViewById去实例化我们需要的cb实例的步骤
- ViewHolder holder = (ViewHolder) arg1.getTag();
- // 改变CheckBox的状态
- holder.cb.toggle(); //---------------------------------------------------------------
- // 将CheckBox的选中状况记录下来
- MyAdapter.getIsSelected().put(arg2, holder.cb.isChecked()); //---------------------------------------------------
- // 调整选定条目
- if (holder.cb.isChecked() == true) {
- checkNum++;
- } else {
- checkNum--;
- }
- // 用TextView显示
- tv_show.setText("已选中"+checkNum+"项");
- }
- });
- }
- // 初始化数据
- private void initDate() {
- for (int i = 0; i < 15; i++) {
- list.add("data" + " " + i);
- }
- }
- // 刷新listview和TextView的显示
- private void dataChanged() {
- // 通知listView刷新
- mAdapter.notifyDataSetChanged();
- // TextView显示最新的选中数目
- tv_show.setText("已选中" + checkNum + "项");
- }
- }
代码中在item的点击事件中,直接调用
holder.cb.toggle();
先改变CheckBox的状态,然后将值存进map记录下来
MyAdapter.getIsSelected().put(arg2, holder.cb.isChecked());
而其他几个Button的点击事件,都是通过遍历list的长度来设置isSelected的值,进而通知listview根据已经变化的adapter刷新,来实现Checkbox的对应选中状态。因为对listview的处理中我们仍然使用了ViewHolder来优化ListView的效率(通过findViewById层层查找是比较耗时的,这里不了解的朋友可以看我另一篇博客android应用开发全程实录-你有多熟悉listview?,全面解析listview的)。
最后,来看下运行效果:
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