在ListView中使用多个布局

要想在一个ListView中使用多个布局文件,比如一个信息List包含了一个信息标题和每个信息对应的时间.
关键的步骤是实现Adapter类的getItemViewType 和getViewTypeCount 这两个方法
getItemViewType(int)
以int数值型返回itemView的类型。一般普通列表的item都是一样的布局，也就是说这个列表只有一种类型，但是很多时候我们需要列表显示不同的item，比如有的列表有普通item和separator两种类型，item用于响应用户点击事件，separator用于分隔item，不可以点击，这样这个列表就有了两种类型，重载这个方法，如果当前位置是item，我们可以返回1，如果是separator我们可以返回2，以此类推。重写getItemViewType方法，这个方法返回0到getViewTypeCount()-1之间的数字或者IGNORE_ITEM

getViewTypeCount()

返回这个Adapter将处理的itemView类型的总个数

1.首先定义一个接口,List中每一个Item项都必须实现它里面的getViewType和getView方法分别表示使用何种类型的View显示,以及如何新建和回收。

public interface Item {
    public int getViewType();
    public View getView(View convertView);
}

2.在Adapter中维护一个实现Item接口的List对象

public class MyListAdapter extends ArrayAdapter<Item> {
    private List<Item> items;
    private LayoutInflater inflater;
 
    public enum RowType {
        // Here we have two items types, you can have as many as you like though
        LIST_ITEM, HEADER_ITEM
    }
 
    public MyListAdapter(Context context, LayoutInflater inflater, List<Item> items) {
        super(context, 0, items);
        this.items = items;
        this.inflater = inflater;
    }
 
    @Override
    public int getViewTypeCount() {
        // Get the number of items in the enum
        return RowType.values().length;
 
    }
 
    @Override
    public int getItemViewType(int position) {
        // Use getViewType from the Item interface
        return items.get(position).getViewType();
    }
 
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Use getView from the Item interface
        return items.get(position).getView(inflater, convertView);
    }
}

3.现在创建一个标题类实现Item接口

public class Header implements Item {
    private final String         name;
 
    public Header(String name) {
        this.name = name;
    }
 
    @Override
    public int getViewType() {
        return RowType.HEADER_ITEM.ordinal();
    }
 
    @Override
    public View getView(LayoutInflater inflater, View convertView) {
        if (convertView == null) {
            // No views to reuse, need to inflate a new view
            convertView = (View) inflater.inflate(R.layout.header, null);
        }
 
        TextView text = (TextView) convertView.findViewById(R.id.headerText);
        text.setText(name);
 
        return convertView;
    }
 
}

4.创建一个信息类实现Item接口

public class EventItem implements Item {
    private final String         str1;
    private final String         str2;
 
    public EventItem(String text1, String text2) {
        this.str1 = text1;
        this.str2 = text2;
    }
 
    @Override
    public int getViewType() {
        return RowType.LIST_ITEM.ordinal();
    }
 
    @Override
    public View getView(LayoutInflater inflater, View convertView) {
        if (convertView == null) {
            convertView = (View) inflater.inflate(R.layout.list_item, null);
        }
 
        TextView text1 = (TextView) convertView.findViewById(R.id.list_content1);
        TextView text2 = (TextView) convertView.findViewById(R.id.list_content2);
        text1.setText(str1);
        text2.setText(str2);
 
        return convertView;
    }
 
}

5.最后是Activity的实现

public class MainActivity extends ListActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        LayoutInflater inflater = LayoutInflater.from(this);
         
        List<Item> items = new ArrayList<Item>();
        items.add(new Header("Friday - November 30th 2012"));
        items.add(new EventItem("8:30am" , "Start work"));
        items.add(new EventItem("9:15am" , "Call Bob"));
        items.add(new EventItem("11:00am", "Meeting with Joe"));
        items.add(new EventItem("5:00pm" , "Freedom!"));
         
        items.add(new Header("Saturday - December 1st 2012"));
        items.add(new EventItem("8:30am" , "Keep sleeping"));
        items.add(new EventItem("10:00am", "Wake up"));
        items.add(new EventItem("11:00am", "Walk the dog"));
        items.add(new EventItem("6:00pm" , "Dinner at John's"));
         
        items.add(new Header("Sunday - December 2rd 2012"));
        items.add(new EventItem("8:30am" , "Keep sleeping"));
        items.add(new EventItem("10:00am", "Wake up"));
        items.add(new EventItem("11:00am", "Walk the dog"));
        items.add(new EventItem("6:00pm" , "Dinner at John's"));
 
        items.add(new Header("Monday - December 3rd 2012"));
        items.add(new EventItem("8:30am" , "Start work"));
        items.add(new EventItem("9:15am" , "Call Bob"));
        items.add(new EventItem("11:00am", "Meeting with Joe"));
        items.add(new EventItem("5:00pm" , "Freedom!"));
         
        MyListAdapter adapter = new MyListAdapter(this, inflater, items);
        setListAdapter(adapter);
    }
 
}