利用ExpandableListView实现树形结构展示

ExpandableListView 是 Android 中的一个组件，它可以用来实现树形结构的数据展示

1. 首先，在 res/layout 目录下创建一个布局文件 list_item.xml，用于显示每个列表项：

<?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="wrap_content"     android:orientation="horizontal"     android:padding="8dp">     <TextView         android:id="@+id/tv_item"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:textSize="16sp" />  </LinearLayout> 

2. 创建一个 Java 类 MyExpandableListAdapter，继承自 BaseExpandableListAdapter：

import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseExpandableListAdapter; import android.widget.TextView;  import java.util.List; import java.util.Map;  public class MyExpandableListAdapter extends BaseExpandableListAdapter {      private Context context;     private List<String> groupList;     private Map<String, List<String>> childList;      public MyExpandableListAdapter(Context context, List<String> groupList, Map<String, List<String>> childList) {         this.context = context;         this.groupList = groupList;         this.childList = childList;     }      @Override     public int getGroupCount() {         return groupList.size();     }      @Override     public int getChildrenCount(int groupPosition) {         return childList.get(groupList.get(groupPosition)).size();     }      @Override     public Object getGroup(int groupPosition) {         return groupList.get(groupPosition);     }      @Override     public Object getChild(int groupPosition, int childPosition) {         return childList.get(groupList.get(groupPosition)).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 false;     }      @Override     public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {         if (convertView == null) {             convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);         }         TextView tvItem = convertView.findViewById(R.id.tv_item);         tvItem.setText(groupList.get(groupPosition));         return convertView;     }      @Override     public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {         if (convertView == null) {             convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);         }         TextView tvItem = convertView.findViewById(R.id.tv_item);         tvItem.setText(childList.get(groupList.get(groupPosition)).get(childPosition));         return convertView;     }      @Override     public boolean isChildSelectable(int groupPosition, int childPosition) {         return true;     } } 

3. 在你的 Activity 或 Fragment 中，初始化 ExpandableListView 并设置适配器：

import android.os.Bundle; import android.widget.ExpandableListView;  import androidx.appcompat.app.AppCompatActivity;  import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map;  public class MainActivity extends AppCompatActivity {      private ExpandableListView expandableListView;     private MyExpandableListAdapter adapter;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          expandableListView = findViewById(R.id.expandableListView);          // 初始化数据         List<String> groupList = new ArrayList<>();         groupList.add("Group 1");         groupList.add("Group 2");         groupList.add("Group 3");          Map<String, List<String>> childList = new HashMap<>();         List<String> childList1 = new ArrayList<>();         childList1.add("Child 1-1");         childList1.add("Child 1-2");         childList.put("Group 1", childList1);          List<String> childList2 = new ArrayList<>();         childList2.add("Child 2-1");         childList2.add("Child 2-2");         childList2.add("Child 2-3");         childList.put("Group 2", childList2);          List<String> childList3 = new ArrayList<>();         childList3.add("Child 3-1");         childList.put("Group 3", childList3);          // 设置适配器         adapter = new MyExpandableListAdapter(this, groupList, childList);         expandableListView.setAdapter(adapter);     } } 

4. 在 res/layout/activity_main.xml 中添加 ExpandableListView：

<?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"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical"     tools:context=".MainActivity">     <ExpandableListView         android:id="@+id/expandableListView"         android:layout_width="match_parent"         android:layout_height="match_parent" />  </LinearLayout> 

现在运行应用程序，你将看到一个树形结构的列表。点击父节点时，子节点将展开或收起。