你真的了解Android ListView吗？

怼烎@ 2022-07-14 20:08 249阅读 0赞

## 什么是Android ListView？ ##

ListView是一个显示可滚动的项目列表视图组。 该列表中的项目使用的是自动插入到列表Adapter ，拉从源内容，如数组或数据库查询，把每个项目导如成被放置到列表的视图。

在android开发中ListView是比较常用的组件，它以列表的形式展示具体内容，并且能够根据数据的长度自适应显示。

说到ListView就不得不说Adapter适配器，因为只有通过Adapter才可以把列表中的数据映射到ListView中。

在android的开发中最Adapter 一共可以分为

*  ArrayAdapter
 *  BaseAdapter
 *  CursorAdapter
 *  HeaderViewListAdapter
 *  ResourceCursorAdapter
 *  SimpleAdapter
 *  SimpleCursorAdapter
 *  WrapperListAdapter

软件开发中最常用的有ArrayAdapter, BaseAdapter, SimpleAdapter。

--------------------

## ListView的实例 ##

### 简单的ListView ###

在List列表中如果不存在过于复杂的东西 我们可以直接去new ArrayAdapter() 来绘制列表，无须继承ArrayAdapter，重写它的方法。但是如果列表中过于复杂的话就需要使用自定义布局来实现List列表。

public class SimpleList extends ListActivity { 
     private String[] mListStr = {
       "姓名：哈哈","性别：男","年龄：25","居住地：北京","邮箱：haha@gmail.com"};
     ListView mListView = null;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
     mListView = getListView();
     setListAdapter(new ArrayAdapter<String>(this,
     android.R.layout.simple_list_item_1, mListStr));
     mListView.setOnItemClickListener(new OnItemClickListener() {
     @Override
     public void onItemClick(AdapterView<?> adapterView, View view, int position,
     long id) {
     Toast.makeText(SimpleList.this,"您选择了" + mListStr[position], Toast.LENGTH_LONG).show();
     }
     });
    
     super.onCreate(savedInstanceState);
     }
    }

### 带标题的ListView列表 ###

使用 simpleAdapter 需要注意的是须要用`Map<String,Object> item` 来保存列表中每一项的显示的title与text , new SimpleAdapter的时候将map中的数据写入 ，程序就会帮我们绘制列表了。

public class TitleList extends ListActivity { 
     private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"};
     private String[] mListStr = { "哈哈", "男", "25", "北京",
     "haha@gmail.com" };
     ListView mListView = null;
     ArrayList<Map<String,Object>> mData= new ArrayList<Map<String,Object>>();;
    
     @Override
     protected void onCreate(Bundle savedInstanceState) {
     mListView = getListView();
    
     int lengh = mListTitle.length;
     for(int i =0; i < lengh; i++) {
     Map<String,Object> item = new HashMap<String,Object>();
     item.put("title", mListTitle[i]);
     item.put("text", mListStr[i]);
     mData.add(item);
     }
     SimpleAdapter adapter = new SimpleAdapter(this,mData,android.R.layout.simple_list_item_2,
     new String[]{
       "title","text"},new int[]{android.R.id.text1,android.R.id.text2});
     setListAdapter(adapter);
     mListView.setOnItemClickListener(new OnItemClickListener() {
     @Override
     public void onItemClick(AdapterView<?> adapterView, View view, int position,
     long id) {
     Toast.makeText(TitleList.this,"您选择了标题：" + mListTitle[position] + "内容："+mListStr[position], Toast.LENGTH_LONG).show();
     }
     });
     super.onCreate(savedInstanceState);
     }
    }

### 带图片的ListView列表 ###

使用 simpleAdapter 来操作 但是构造simpleAdapter的时候须要使用我们自己写的布局来完成 ，因为系统的布局已经不能满足需求了，同样`Map<String,Object> item` 来保存列表中每一项须要的显示内容 如 图片 标题 内容等。

activity\_main.xml

<?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="?android:attr/listPreferredItemHeight">
     <ImageView android:id="@+id/image" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" />
     <TextView android:id="@+id/title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@+id/image" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:layout_above="@+id/text" android:layout_alignWithParentIfMissing="true" android:gravity="center_vertical" android:textSize="15dip" />
     <TextView android:id="@+id/text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" />
    </RelativeLayout>

MainActivity.java

public class MainActivity extends ListActivity { 
     private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"};
     private String[] mListStr = { "哈哈", "男", "25", "北京",
     "haha@gmail.com" };
     ListView mListView = null;
     ArrayList<Map<String,Object>> mData= new ArrayList<Map<String,Object>>();;
    
     @Override
     protected void onCreate(Bundle savedInstanceState) {
     mListView = getListView();
    
     int lengh = mListTitle.length;
     for(int i =0; i < lengh; i++) {
     Map<String,Object> item = new HashMap<String,Object>();
     item.put("image", R.drawable.jay);
     item.put("title", mListTitle[i]);
     item.put("text", mListStr[i]);
     mData.add(item);
     }
     SimpleAdapter adapter = new SimpleAdapter(this,mData,R.layout.iconlist,
     new String[]{
       "image","title","text"},new int[]{R.id.image,R.id.title,R.id.text});
     setListAdapter(adapter);
     mListView.setOnItemClickListener(new OnItemClickListener() {
     @Override
     public void onItemClick(AdapterView<?> adapterView, View view, int position,
     long id) {
     Toast.makeText(IconList.this,"您选择了标题：" + mListTitle[position] + "内容："+mListStr[position], Toast.LENGTH_LONG).show();
     }
     });
     super.onCreate(savedInstanceState);
     }
    }

### 自定义布局BaseAdapter修改列表颜色 ###

因为通过直接 构造系统的布局来绘制列表方法肯定是有限的，所以我们需要重写绘制方法 ，写一个类去继承BaseAdapter 并实现这个类中的方法，listView在一开始绘制的时候首先会调用getCout()方法得到绘制次数 ，然后会实例化自己定义的BaseAdapter通过getView()方法一层一层绘制ListView,所以我们可以在这里面根据position(当前绘制的ID)来任意的修改绘制的内容，做出好看漂亮的ListView,下面这个例子我通过重写getView修改每个列表的颜色 并且实现用户选中后成高亮状态。

activity\_main.xml

<?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="wrap_content">
     <ImageView android:id="@+id/color_image" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" />
     <TextView android:id="@+id/color_title" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/color_image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="15dip" />
     <TextView android:id="@+id/color_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/color_image" android:layout_below="@+id/color_title" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" />
    </RelativeLayout>

MianActivity.java

public class MianActivity extends ListActivity { 
     private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"};
     private String[] mListStr = { "哈哈", "男", "25", "北京",
     "haha@gmail.com" };
     ListView mListView = null;
     MyListAdapter myAdapter = null;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
     mListView = getListView();
     myAdapter = new MyListAdapter(this);
     setListAdapter(myAdapter);
     mListView.setOnItemClickListener(new OnItemClickListener() {
     @Override
     public void onItemClick(AdapterView<?> adapterView, View view, int position,
     long id) {
     View v=adapterView.getChildAt(position);
     v.setBackgroundColor(Color.RED);
     Toast.makeText(ColorList.this,"您选择了" + mListStr[position], Toast.LENGTH_LONG).show();
     }
     });
    
     super.onCreate(savedInstanceState);
     }
    
     class MyListAdapter extends BaseAdapter {
     private int[] colors = new int[] { 0xff626569, 0xff4f5257 };
     public MyListAdapter(Context context) {
     mContext = context;
     }
    
     public int getCount() {
     return mListStr.length;
     }
    
     @Override
     public boolean areAllItemsEnabled() {
     return false;
     }
    
     public Object getItem(int position) {
     return position;
     }
    
     public long getItemId(int position) {
     return position;
     }
    
     public View getView(int position, View convertView, ViewGroup parent) {
     ImageView iamge = null;
     TextView title = null;
     TextView text = null;
     if (convertView == null) {
     convertView = LayoutInflater.from(mContext).inflate(R.layout.colorlist, null);
     iamge = (ImageView) convertView.findViewById(R.id.color_image);
     title =(TextView) convertView.findViewById(R.id.color_title);
     text= (TextView) convertView.findViewById(R.id.color_text);
     }
     int colorPos = position % colors.length;
     convertView.setBackgroundColor(colors[colorPos]);
     title.setText(mListTitle[position]);
     text.setText(mListStr[position]);
     iamge.setImageResource(R.drawable.jay);
     return convertView;
     }
    
     private Context mContext;
     }
    }

### 自定义布局ArrayAdapter ###

ArrayAdapter是BaseAdapter的子类，ArrayAdapter不仅具有BaseAdapter的所有方法还自定义了一些新的方法来处理列表项，所以单纯的从功能能上来讲ArrayAdapter远远强与BaseAdapter，如果是绘制一些数量比较少的列表建议使用BaseAdapter 如果绘制一些比较复杂的列表项 并且列表项很多的 建议使用ArrayAdapter。

activity\_main.xml

<?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="wrap_content">
     <Button android:id="@+id/array_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="用户" />
     <ImageView android:id="@+id/array_image" android:layout_toRightOf="@+id/array_button" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentTop="true" android:layout_alignParentBottom="true" android:adjustViewBounds="true" android:padding="2dip" />
     <TextView android:id="@+id/array_title" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/array_image" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="15dip" />
     <TextView android:id="@+id/array_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_toRightOf="@+id/array_image" android:layout_below="@+id/array_title" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:singleLine="true" android:ellipsize="marquee" android:textSize="20dip" />
    
    </RelativeLayout>

MianActivity.java

public class ArrayList extends ListActivity { 
     private String[] mListTitle = { "姓名", "性别", "年龄", "居住地","邮箱"};
     private String[] mListStr = { "哈哈", "男", "25", "北京",
     "haha@gmail.com" };
     ListView mListView = null;
     MyListAdapter myAdapter = null;
     ArrayList arrayList = null;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
     arrayList = this;
     mListView = getListView();
     myAdapter = new MyListAdapter(this,R.layout.arraylist);
     setListAdapter(myAdapter);
     super.onCreate(savedInstanceState);
     }
    
     public class MyListAdapter extends ArrayAdapter<Object> { 
     int mTextViewResourceID = 0;
     private Context mContext;
     public MyListAdapter(Context context, int textViewResourceId) {
     super(context, textViewResourceId);
     mTextViewResourceID = textViewResourceId;
     mContext = context;
     }
    
     private int[] colors = new int[] { 0xff626569, 0xff4f5257 };
    
     public int getCount() {
     return mListStr.length;
     }
    
     @Override
     public boolean areAllItemsEnabled() {
     return false;
     }
    
     public Object getItem(int position) {
     return position;
     }
    
     public long getItemId(int position) {
     return position;
     }
    
     public View getView(final int position, View convertView, ViewGroup parent) {
     ImageView iamge = null;
     TextView title = null;
     TextView text = null;
     Button button = null;
     if (convertView == null) {
     convertView = LayoutInflater.from(mContext).inflate(
     mTextViewResourceID, null);
     iamge = (ImageView) convertView.findViewById(R.id.array_image);
     title = (TextView) convertView.findViewById(R.id.array_title);
     text = (TextView) convertView.findViewById(R.id.array_text);
     button = (Button)convertView.findViewById(R.id.array_button);
     button.setOnClickListener(new OnClickListener() {
    
     @Override
     public void onClick(View arg0) {
     Toast.makeText(arrayList,"您点击的第"+position +"个按钮", Toast.LENGTH_LONG).show();
    
     }
     });
     }
     int colorPos = position % colors.length;
     convertView.setBackgroundColor(colors[colorPos]);
     title.setText(mListTitle[position]);
     text.setText(mListStr[position]);
     if(colorPos == 0)
     iamge.setImageResource(R.drawable.jay);
     else
     iamge.setImageResource(R.drawable.image);
     return convertView;
     }
     }
    }