android 之 ListView相关

Posted 2020-09-20 叶常绿

ListView是一种列表视图，其将ListAdapter所提供的各个控件显示在一个垂直且可滚动的列表中。需要注意的为创建适配器并将其设置给ListView。

1.ArrayAdapter

ArrayAdapter由3个参数进行构造，第一个为Context，第二个为在R文件中定义的Layout，也可用系统的R文件，第三个参数是一个数组，数组中每一项的类型没有限制。

系统默认的布局方式可通过android.R.layout.XX定义。

private static String[] data={"a","b","c","d"};
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
      //  setContentView(R.layout.main);

            ListView listview=new ListView(this);
            ArrayAdapter adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,data);
            listview.setAdapter(adapter);
            setContentView(listview);
    }

 

若自定义ListView中每一项TextView的样式arraylayout.xml如下：

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="wrap_content"
    android:gravity="center_horizontal" />

Activity中，指定ArrayAdapter第二个参数为arraylayout.xml：

private static String[] data={"a","b","c","d"};
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
      //  setContentView(R.layout.main);

            ListView listview=new ListView(this);
            ArrayAdapter adapter=new ArrayAdapter<String>(this,R.layout.arraylayout,data);
            listview.setAdapter(adapter);
            setContentView(listview);
    }

2 SimpleAdapter

SimpleAdapter的ArrayList里的每一项都是一个Map<String,?>类型，每一项Map对象都和ListV中的一项进行数据绑定一一对应。

private ListView listview;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        listview=new ListView(this);
       data2 = new ArrayList<Map<String, Object>>();
        Map<String, Object> item;
        item = new HashMap<String, Object>();
        item.put("姓名", "张三");
        item.put("性别", "男");
        item.put("年龄", "25");
        data2.add(item);
        item = new HashMap<String, Object>();
        item.put("姓名", "李四");
        item.put("性别", "男");
        item.put("年龄", "33");
        data2.add(item);
        item = new HashMap<String, Object>();
        item.put("姓名", "小王");
        item.put("性别", "女");
        item.put("年龄", "31");
        data2.add(item);
        SimpleAdapter adapter = new SimpleAdapter(this, data2,
                R.layout.simplelayout, new String[] { "姓名", "性别","年龄" }, new int[] {
                        R.id.tv01, R.id.tv02,R.id.tv03 });
        listview.setAdapter(adapter);
        setContentView(listview);

其中ListView中每项的布局文件如下：

<?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/tv01" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:width="150dp" />
    <TextView android:id="@+id/tv02" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:width="150dp"/>
    <TextView android:id="@+id/tv03" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:width="150dp"/>
</LinearLayout>

如果设置Activity的布局文件包含不仅ListView，如下：

<?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">
    <ImageView android:layout_width="fill_parent" android:layout_height="wrap_content"
    android:src="@drawable/img01"/>
    <ListView android:id="@+id/listview01" android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:choiceMode="singleChoice" />
</LinearLayout>

在Activity中：

setContentView(R.layout.main);
        listview=(ListView) findViewById(R.id.listview01);
        listview.setAdapter(adapter);

3 BaseAdapter

public class mainActivity extends Activity {
    /** Called when the activity is first created. */
    int [] drawableIds={R.drawable.img01,R.drawable.img02,R.drawable.img03};
    int [] msgIds={R.string.str1,R.string.str2,R.string.str3};
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        setContentView(R.layout.main);
        ListView listview=(ListView) findViewById(R.id.listview01);
        BaseAdapter ba=new BaseAdapter() {
            
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                // TODO Auto-generated method stub
                LinearLayout ll=new LinearLayout(mainActivity.this);
                ll.setOrientation(LinearLayout.HORIZONTAL);
                ll.setPadding(5, 5, 5, 5);
                ImageView ii=new ImageView(mainActivity.this);
                ii.setImageDrawable(getResources().getDrawable(drawableIds[position]));
                ii.setScaleType(ImageView.ScaleType.FIT_XY);
                ii.setLayoutParams(new Gallery.LayoutParams(50,50));
                ll.addView(ii);
                TextView tv=new TextView(mainActivity.this);
                tv.setText(getResources().getText(msgIds[position]));
                tv.setTextSize(24);
                tv.setTextColor(mainActivity.this.getResources().getColor(R.color.white));
                tv.setPadding(5, 5, 5, 5);
                tv.setGravity(Gravity.LEFT);
                ll.addView(tv);
                return ll;
            }
            
            @Override
            public long getItemId(int position) {
                // TODO Auto-generated method stub
                return 0;
            }
            
            @Override
            public Object getItem(int position) {
                // TODO Auto-generated method stub
                return null;
            }
            
            @Override
            public int getCount() {
                // TODO Auto-generated method stub
                return 3;
            }
        };
        listview.setAdapter(ba);
    }
}

4 ListActivity

若使用ListActivity，则Activity里的ListView将充满屏幕。

在布局文件中，必须定义一个ListView，其Id为@id/android:list;另一个需要定义但并不是必须的是id为@id/android:empty的TextView，其为ListView中无数据时显示的内容。

<?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">
    <ListView android:id="@id/android:list" android:layout_width="fill_parent"
        android:layout_height="fill_parent" />
    <TextView android:id="@id/android:empty" android:layout_width="fill_parent"
        android:layout_height="fill_parent" android:text="没有任何数据" />
</LinearLayout>

Activity中，ListView每行设置和之前方法一样。

String [] data={"a","b","c","d"};
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
    setContentView(R.layout.main);
    setListAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,data));
    
}