[zzerX@blog ~ ]:

Android ListView的批量处理(多选/反选/删除)

在Android开发中经常遇到使用ListView的情况,有时候需要的不仅仅是列表显示,还有长按列表进行多选,并且批量删除的情况,在这里记录一下自己的所学。

先上效果图:

几个需要用到的核心方法:

//设置多选模式,下面的方法基于设置多选模式
list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

//获取Item选择状态:
list.isItemChecked(i);

//设置Item选择状态
list.setItemChecked(i, true);

//清除全部选中状态
list.clearChoices();

简述原理

多选模式下,ListView在触发OnItemClick时会设置Item为true,再点一次为false,

我们只需创建一个isMultiplSelectionMode来传递判断当前为多选模式,

在全选时遍历list.setItemChecked()为true;

反选时遍历list.isItemChecked(i)为true的set为false,false则为true,

删除时直接遍历list.isItemChecked(i)为true的在适配器上直接remove删除即可

假装深入源码

我们知道ListView继承AbsListView,
通过查看他的源码的isItemChecked方法,可以看到

...
    public boolean isItemChecked(int position) {
        if (mChoiceMode != CHOICE_MODE_NONE && mCheckStates != null) {
            return mCheckStates.get(position);
        }

        return false;
    }
...

首先判断了当前选择模式不等于默认的单选模式 && mCheckStates 不为空的时候从这个mCheckStates去获取当前的item的选择状态,那我们再来看看这个mCheckStates到底是什么?

/**
 * Running state of which positions are currently checked
 */
SparseBooleanArray mCheckStates;

mCheckStates是SparseBooleanArray的实例,SparseBooleanArray实现了Cloneable接口,再往下就离题了,现在知道了mCheckStates本质是一个保存着Boolean的Array,并且这个Array与Items有关系,setItemChecked/isItemChecked都使用了mCheckStates,获取的就是Item的状态,逻辑他已经帮我们写好,我们只用用好isItemChecked即可。
(好像说了和没说一样,尴尬了|;)

直接上源码把

activity_main.xml

先界面:1个显示选择个数的TextView,3个Button,1个ListView

<?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">

	<LinearLayout
        android:visibility="gone"
        android:id="@+id/ItemToolBar"
		android:orientation="horizontal"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content">

		<TextView
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:text="选择了0项"
			android:id="@+id/counttext"/>

		<Button
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:text="全选"
			android:id="@+id/all"/>

		<Button
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:text="反选"
			android:id="@+id/unall"/>

		<Button
			android:layout_width="wrap_content"
			android:layout_height="wrap_content"
			android:text="删除"
			android:id="@+id/del"/>

	</LinearLayout>

	<ListView
		android:layout_width="match_parent"
		android:layout_height="match_parent"
		android:id="@+id/mylistview"/>

</LinearLayout>

listview_item.xml

当然还有Item项的界面,简单点,两个TextView,一个标题,一个内容

<?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="wrap_content"
		android:layout_height="wrap_content"
		android:text="Large Text"
		android:textAppearance="?android:attr/textAppearanceLarge"
		android:id="@+id/lv_text1"/>

	<TextView
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="Small Text"
		android:textAppearance="?android:attr/textAppearanceSmall"
		android:id="@+id/lv_text2"/>

</LinearLayout>

MyAdapter.java
ListView的适配器,重写了getView方法,让当前可视部分的项目状态为选中时改变背景颜色,关于geiView的ViewHolder部分可以看这的文章【Android开发中常用的ListView列表的优化方式ViewHolder】,简而言之就是一种列表优化方式。

public class MyAdapter extends BaseAdapter {

   public ArrayList<HashMap<String, Object>> balistItem = new ArrayList<HashMap<>>();
    
    @Override
    public int getCount() {
        return balistItem.size();
    }
    
    @Override
    public long getItemId(int p1) {
        return p1);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if (convertView == null) {
            viewHolder = new ViewHolder();
            convertView = View.inflate(MainActivity.CONTEXT, R.layout.listview_item, null);
            viewHolder.title = convertView.findViewById(R.id.lv_text1);
            viewHolder.text = convertView.findViewById(R.id.lv_text2);
            convertView.setTag(viewHolder);
  
        } else {

            viewHolder = (ViewHolder)convertView.getTag();
        }
        
        viewHolder.title.setText(balistItem.get(position).get("标题").toString());
        viewHolder.text.setText(balistItem.get(position).get("内容").toString());

        //判断position位置是否被选中,改变颜色
        if (MainActivity.list.isItemChecked(position) && MainActivity.isMultipleSelectionMode) {
                convertView.setBackgroundColor(0xffff521d);
            } else {
                convertView.setBackgroundColor(0xff1E90FF);
        }
        return convertView;
    }


    public MyAdapter(List<? extends Map<String, ?>> data) {
        this.balistItem = (ArrayList<HashMap<String, Object>>) data;
    }    

    private static class ViewHolder {
        TextView title;
        TextView text;
        

        public static ViewHolder newsInstance(View convertView) {
            ViewHolder holder = (ViewHolder) convertView.getTag();

            if (holder == null) {
                holder = new ViewHolder();
                holder.title = convertView.findViewById(R.id.lv_text1);
                holder.text = convertView.findViewById(R.id.lv_text2);
                convertView.setTag(holder);
            }

            return holder;
        }

    }
}

MainActivity.java
创建数据,并添加至适配器,设置长按进入多选模式,

public class MainActivity extends AppCompatActivity {

    static ListView list;
    static MyAdapter listItemAdapter;//适配器
    static boolean isMultipleSelectionMode;//判断进入多选模式
    public static ArrayList<HashMap<String, Object>> AdapterList = new ArrayList<>();  //数据

    public static Context CONTEXT;
    TextView counttext;
    LinearLayout ItemToolBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CONTEXT = this.getApplicationContext();
        //初始化数据
        initData();

         counttext = this.findViewById(R.id.counttext);//选中时更改的textview
         ItemToolBar = this.findViewById(R.id.ItemToolBar);//多选模式的工具栏
         

        list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        listItemAdapter = new MyAdapter(AdapterList); //新建并配置ArrayAapeter
        list.setAdapter(listItemAdapter);
        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> p, View v, int index,
                                    long arg3) {
                if (isMultipleSelectionMode) {
                    setCountChange();             

                }
                listItemAdapter.notifyDataSetChanged();
               
            }
        });



        list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long itemId) {

                if (isMultipleSelectionMode) {
                    ItemToolBar.setVisibility(View.GONE);
                    isMultipleSelectionMode = false;
                    
                    list.clearChoices();//取消选中状态
                    Toast.makeText(CONTEXT, "退出多选模式", Toast.LENGTH_LONG).show();
                } else {
ItemToolBar.setVisibility(View.VISABLE);                             isMultipleSelectionMode =true;
                    listItemAdapter.notifyDataSetChanged();
                    //多选模式
                    Toast.makeText(CONTEXT, "进入多选模式", Toast.LENGTH_LONG).show();
                    for(int i = 0;i < listItemAdapter.balistItem.size();i++){
                        Log.d("del","Item" + i + "的状态:" + list.isItemChecked(i));

                    }


                    return true;

                }

                listItemAdapter.notifyDataSetChanged();
                setCountChange();

                return false;
            }
        });
//设置按钮单机事件绑定
 setButtonClick();

    }
    public void setCountChange(){
        counttext.setText("选中了" + list.getCheckedItemCount() +"项");
    }

    public void initData(){
        list = this.findViewById(R.id.mylistview);

        for(int i = 0;i< 5;i++){
            HashMap<String,Object> map = new HashMap<>();
            map.put("标题","这是标题" + i);
            map.put("内容","这是内容" + i);
            AdapterList.add(map);
        }
    }

    public void setButtonClick(){
        Button all = this.findViewById(R.id.all);
        Button unall = this.findViewById(R.id.unall);
        Button del = this.findViewById(R.id.del);

        all.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               for(int i = 0;i < listItemAdapter.balistItem.size();i++){
                  list.setItemChecked(i,true);
               }
                setCountChange();
            }
        });

        unall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                for(int i = 0;i < listItemAdapter.balistItem.size();i++){
                    if(list.isItemChecked(i)){
                        list.setItemChecked(i,false);
                        list.setItemChecked(i,false);
                    }else {
                        list.setItemChecked(i,true);
                    }
                }
                setCountChange();
            }
        });

        del.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               
                for(int i = 0;i < listItemAdapter.balistItem.size();i++){
                    if(list.isItemChecked(i)){
                        listItemAdapter.balistItem.remove(i);
                        listItemAdapter.notifyDataSetChanged();
                    }
                }
                list.clearChoices();
                setCountChange();
            }
        });



    }

}

demo apk文件下载地址:https://files.cnblogs.com/files/zzerx/app-debug(1).apk

— Feb 24, 2020