ExpandableListView

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ExpandableListView顾名思义，为可展开的ListView（相当于ListView的每一行都是一个可以点击并展开的ListView）

Layout

创建一个ExpandableListView的Layout
activity_main

<?xml version="1.0" encoding="utf-8"?><ExpandableListView xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/expand_list"    android:layout_width="wrap_content"    android:layout_height="wrap_content"></ExpandableListView>

再创建两个Layout，一个是一级目录的Item布局，另一个则是二级目录的Item布局

item

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal"    >    <TextView        android:id="@+id/GroupItem"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="TextView"        android:gravity="center_horizontal"/></LinearLayout>

child_item

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    >    <TextView        android:id="@+id/ChildItem"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="TextView" /></LinearLayout>

类文件

MainActivity

public class MainActivity extends AppCompatActivity {    private ExpandableListView expandListView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        ArrayList<String> list = new ArrayList<>();        ExpandAdapter adapter = new ExpandAdapter(list, this);        expandListView = (ExpandableListView)findViewById(R.id.expand_list);        expandListView.setAdapter(adapter);    }}

Item类

public class Item {    public ArrayList<String> number;    public String course;    public Item(String course,ArrayList number){        this.course = course;        this.number = number;    }}

ExpandAdapter类：ExpandableListView的适配器类，大部分需要重写的方法和BaseAdapter一样，只不过多了Group及Child的区别，便不再赘叙。

public class ExpandAdapter extends BaseExpandableListAdapter implements ExpandableListView.OnGroupCollapseListener, ExpandableListView.OnGroupExpandListener {    Context context;    ArrayList<Item> list;    Boolean[] isOpen;    /*创建一个和一级目录一样数量元素的数组,用于保存及判断一级目录是否被打开，     *这个数组在该例子中并没有作用，仅仅是为了让继承的两个接口所重写的方法更具体一些     *即onGroupCollapse(int groupPosition)、onGroupExpand(int groupPosition)     */    public ExpandAdapter(ArrayList list,Context context){        this.list=  list;        this.context = context;        initListContext();    }    /*为方便起见，直接添加一些简单的数据源*/    public void initListContext() {        ArrayList<String> number = new ArrayList<>();        for (int i=0;i<5;i++){            number.add("课程"+i);        }        list.add(new Item("Java",number));        list.add(new Item("C++",number));        list.add(new Item("Python",number));        list.add(new Item("Math",number));        list.add(new Item("English",number));    }    @Override    public int getGroupCount() {        return list.size();    }    @Override    public int getChildrenCount(int groupPosition) {        return list.get(groupPosition).number.size();    }    @Override    public Object getGroup(int groupPosition) {        return list.get(groupPosition);    }    //返回二级标签的内容    @Override    public Object getChild(int groupPosition, int childPosition) {        return list.get(groupPosition).number.get(childPosition);    }    @Override    public long getGroupId(int groupPosition) {        return groupPosition;    }    @Override    public long getChildId(int groupPosition, int childPosition) {        return childPosition;    }    @Override    public boolean hasStableIds() {        return true;    }    @Override    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {        TextView group_text;        if (convertView == null) {            convertView =  LinearLayout.inflate(                    context, R.layout.item, null);        }        group_text = (TextView) convertView.findViewById(R.id.GroupItem);        group_text.setText(list.get(groupPosition)                .course);        return convertView;    }    @Override    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {       ViewHolder viewHolder;        if(convertView == null){            viewHolder = new ViewHolder();            convertView  = LayoutInflater.from(context).inflate(R.layout.child_item,null);            viewHolder.itemOfText = (TextView) convertView.findViewById(R.id.ChildItem);            convertView.setTag(viewHolder);        }else{            viewHolder  = (ViewHolder) convertView.getTag();        }        viewHolder.itemOfText.setText(list.get(groupPosition).number.get(childPosition));        return convertView;    }    @Override    public boolean isChildSelectable(int groupPosition, int childPosition) {        return true;    }    //ExpandableListView.OnGroupCollapseListener接口重写的方法    //当二级标签未展开时回调    @Override    public void onGroupCollapse(int groupPosition) {        isOpen[groupPosition] = false;    }    //ExpandableListView.OnGroupExpandListener接口重写的方法    //当二级标签展开时回调    @Override    public void onGroupExpand(int groupPosition) {        isOpen[groupPosition] = true;    }}class ViewHolder{       public  TextView itemOfText;}

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ExpandableListView

相关知识:

Layout

类文件