安卓开发-ListView的适配器和监听器/ExpandableListView的使用

《一：BaseAdapter的简单使用》

1.定义类MyAdapter,继承BaseAdapter:

public class MyAdapter extends BaseAdapter {
    //将布局文件转换成View对象
    private LayoutInflater mLayoutInflater;
    //ListView中的值
    private List<String> mDatas;



    //在构造器中将值传进并初始化成员变量
    public MyAdapter(Context c) {
        mLayoutInflater = LayoutInflater.from(c);
    }

    //告诉ListView默认显示几条数据
    public int getCount() {
        return mDatas != null ? mDatas.size() : 0;
    }

    //ListView中若子元素有多个组件组成，应定义一个组件缓存类
    class ViewHolder{
        TextView v1;
        TextView v2;
    }


    //只有当getCount不为0时才会被多次调用，
    //position:ListView的索引
    //convertView:缓存的ItemView,最底层露出一点或不露，会预加载，当滑动了一个时才不为空
    //ViewGroup:每个ItemView的容器，返回的view直接添加到容器中
    public View getView(int position, View convertView, ViewGroup parent) { 
        ViewHolder viewHolder = null;
        //开始为空，预加载出来后才不为空
        if(convertView == null){
            //将一个子布局转换成view，然后才能对子布局中的控件赋值等操作
            convertView = mLayoutInflater.inflate(android.R.layout.simple_list_item_2, null);

            viewHolder = new ViewHolder();
            viewHolder.v1 = (TextView) convertView.findViewById(android.R.id.text1);
            viewHolder.v2 = (TextView) convertView.findViewById(android.R.id.text2);

            convertView.setTag(viewHolder);
        }else{
            viewHolder = (ViewHolder) convertView.getTag();
        }

        //将传进来的值与子布局中的控件绑定
        viewHolder.v1.setText(mDatas.get(position));
        viewHolder.v2.setText(mDatas.get(position));

        //返回的是整个引用的子布局对象，而不是里面的一个小控件
        return convertView;
    }

    public void setDatas(List<String> datas){
        mDatas = datas;
    }

    public Object getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return 0;
    }

}

2.在MainActivity中调用MyAdapter：

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //1.获取ListView控件
        ListView listView = (ListView)findViewById(R.id.lv);

        //2.给列表ListView设置值
        List<String> datas = new ArrayList<>();
        for (int i = 0; i < 100; i++) {
            datas.add("界面" + i);
        }

        //3.传入Context对象创建适配器对象，并与ListView绑定
        MyAdapter adapter = new MyAdapter(this);
        listView.setAdapter(adapter);

        //4.将数据传到适配器中：
        adapter.setDatas(datas);

        //5.数据一般是从服务器发送而来，有延迟现象，调用此方法会执行getCount,getView
        adapter.notifyDataSetChanged();
    }

}

《二：ArrayAdapter》

ListView listView = (ListView)findViewById(R.id.lv);

ArrayAdapter<String> adpater = new ArrayAdapter(this, android.R.layout.simple_list_item_1, android.R.id.text1,datas);

listView.setAdapter(adapter);

《三：SimpleAdapter》

1.在MainActivity中：

ListView listView = (ListView) findViewById(R.id.lv);

        List<Map<String, Object>> datas = new ArrayList<>();
        for (int i = 1; i <= 7; i++) {
            Map<String, Object> dataMap = new HashMap<>();
            datas.add(dataMap);
            dataMap.put("pic", R.drawable.a1);
            dataMap.put("textView", "文本" + i);
        }

        SimpleAdapter simpleAdapter = new SimpleAdapter(this, datas,
                R.layout.simpleadapter_item_layout, new String[] { "pic",
                        "textView" }, new int[]{ R.id.iv, R.id.tv });
        listView.setAdapter(simpleAdapter);

2.simpleadapter_item_layout.xml中：

<?xml version="1.0" encoding="utf-8"?>"E:/java/OpenSource/code/AndroidApp/SimpleAdapter/res/layout/activity_main.xml"
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/iv"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_gravity="center_vertical" />

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#F00"
        android:layout_margin="20dp" />

</LinearLayout>

《四：ListView的监听器》

1.滑动监听器：

ListView.setOnScrollListener(new OnScrollListener(){
    //1.滑动状态改变时调用：
    //OnScrollListener.SCROLL_STATE_FLING : 惯性滑动
    //OnScrollListener.SCROLL_STATE_IDLE  : 不动
    //OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:拖拽滑动
    public void onScrollStateChanged(AbsListView view, int scrollState){

    }
    //2.列表滑动就会调用此函数：列表显示第一项，可见几项，总共项数
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount){
    }

2.点击监听器：

//1.在MyAdapter中：
public Object getItem(int position){
   return mDatas != null ? mDatas.get(position) : null);
   }


//2.在MainActivity中：
ListView.setOnItemClickListener(new OnItemClickListener(){
    public void onItemClick(AdapterView<?> parent, View view, int position, long id){
    String item = （String)adapter.getItem(position);
    }
     });

《五：ExpandableListView》

1.创建适配器类：

public class MyAdapter extends BaseExpandableListAdapter {
    private LayoutInflater mInflater;

    private List<String> mGroupNames;
    private Map<String, List<String>> mChildNames;

    public MyAdapter(Context c, List<String> groupNames, Map<String, List<String>> childNames){
        mInflater = LayoutInflater.from(c);

        mGroupNames = groupNames;
        mChildNames = childNames;
    }

    public int getGroupCount() {
        return mGroupNames.size();
    }

    public int getChildrenCount(int groupPosition) {
        return mChildNames.size();
    }

    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        TextView view = null;
        if(convertView == null){
            convertView = mInflater.inflate(android.R.layout.simple_list_item_1, null);
            view = (TextView)convertView.findViewById(android.R.id.text1);

            convertView.setTag(view);
        }else{
            view = (TextView)convertView.getTag();
        }

        view.setText(mGroupNames.get(groupPosition));

        return convertView;
    }

    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        TextView view = null;
        if(convertView == null){
            convertView = mInflater.inflate(android.R.layout.simple_list_item_1, null);
            view = (TextView)convertView.findViewById(android.R.id.text1);

            convertView.setTag(view);
        }else{
            view = (TextView)convertView.getTag();
        }
        String groupName = mGroupNames.get(groupPosition);
        List<String> childNames = mChildNames.get(groupName);
        view.setText(childNames.get(childPosition));

        return convertView;
    }





    public Object getGroup(int groupPosition) {
        return null;
    }

    public Object getChild(int groupPosition, int childPosition) {
        return null;
    }

    public long getGroupId(int groupPosition) {
        return 0;
    }

    public long getChildId(int groupPosition, int childPosition) {
        return 0;
    }

    public boolean hasStableIds() {
        return false;
    }


    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
    }

}

2.在MainActivity中：

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //1.得ExpandableListView对象
        ExpandableListView expandableListView = (ExpandableListView)findViewById(R.id.ev);

        //2.创建每组的名字集合
        List<String> groupNames = new ArrayList<>();
        //3.创建每组的中的数据map
        Map<String,List<String>> childNames = new HashMap<>();
        for (int i = 0; i < 4; i++) {
            groupNames.add("Group" + i);
        }
        for (int i = 0; i < groupNames.size(); i++) {
            String groupName = groupNames.get(i);
            List<String> childs = new ArrayList<>();
            for (int j = 0; j < 4; j++) {
                childs.add("Child" + j);
            }
            childNames.put(groupName, childs);
        }

        //4.创建适配器，并绑定数据
        MyAdapter adapter = new MyAdapter(this, groupNames, childNames);
        //5.将列表与适配器绑定
        expandableListView.setAdapter(adapter);
    }

}