ExpandableListView实现Listview折叠工具

时间：2022-02-28 19:42:35
 

ExpandableListView使用解析这是一个比较老的控件工具   这个和ListView差不多

1.先来一个二级列表实现  主函数 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">


    <ExpandableListView
        android:id="@+id/tree_view_simple"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
         >
    </ExpandableListView>


</LinearLayout>




2.然后创建实体类 
/**
 *
 * 班级实体类
 * Created by MH on 2016/6/16.
 */
public class Classes {


    // 班级名
    public String name;


    // 班级中的学生列表
    public List<String> students;

}



3.设置适配器     这里可能有一些不明白  
  • getGroupCount():获取一级条目的数量。
  • getChildrenCount():获取二级条目的数量。
  • getGroupView():获取一级条目的对应布局。

  • getChildView()：获取二级条目对应的布局。

  • setAdapter()设置适配器

public class ClassesExpandableListViewAdapter extends BaseExpandableListAdapter {


    // 班级的集合
    private List<Classes> classes;

    // 创建布局使用
    private Activity activity;


    public ClassesExpandableListViewAdapter(List<Classes> classes, Activity activity) {
        this.classes = classes;
        this.activity = activity;
    }

    @Override
    public int getGroupCount() {
        // 获取一级条目的数量  就是班级的大小
        return classes.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        // 获取对应一级条目下二级条目的数量，就是各个班学生的数量
        return classes.get(groupPosition).students.size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        // 获取一级条目的对应数据  ，感觉没什么用
        return classes.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        // 获取对应一级条目下二级条目的对应数据  感觉没什么用
        return classes.get(groupPosition).students.get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        // 直接返回，没什么用
        return groupPosition;
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        // 直接返回，没什么用
        return childPosition;
    }

    @Override
    public boolean hasStableIds() {
        // 谁知道这个是干什么。。。。
        return false;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

        // 获取对应一级条目的View  和ListView 的getView相似

        return getGenericView(classes.get(groupPosition).name);
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

        // 获取对应二级条目的View  和ListView 的getView相似
        return getGenericView(classes.get(groupPosition).students.get(childPosition));
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        // 根据方法名，此处应该表示二级条目是否可以被点击   先返回true 再讲
        return true;
    }


    /**
     * 根据字符串生成布局，，因为我没有写layout.xml 所以用java 代码生成
     *
     *      实际中可以通过Inflate加载自己的自定义布局文件，设置数据之后并返回
     * @param string
     * @return
     */
    private TextView getGenericView(String string) {

        AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);

        TextView textView = new TextView(activity);
        textView.setLayoutParams(layoutParams);

        textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);

        textView.setPadding(40, 20, 0, 20);
        textView.setText(string);
        textView.setTextColor(Color.RED);
        return textView;
    }

}

4.主函数代码 
public class MainActivity extends AppCompatActivity {
    private ExpandableListView listview;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 查找控件
        listview = findViewById(R.id.tree_view_simple);
        // 初始化数据
        List<Classes> classesList = new ArrayList<>();
        for(int i = 1 ;i<3;i++) {
            Classes classes = new Classes();
            classes.name = "计算机"+i+"班";
            List<String> list = new ArrayList<>();
            list.add("mm");
            list.add("dd");
            classes.students = list;
            classesList.add(classes);
        }
        // 构造适配器
        ClassesExpandableListViewAdapter adapter = new ClassesExpandableListViewAdapter(classesList,this);
        // 设置适配器
        listview.setAdapter(adapter);
    }
}

当然二级到这里就结束了    下面开始三级列表实现

5.一样创建一个实体类 
/**
 * 大学实体类
 * Created by MH on 2016/6/16.
 */
public class College {

    // 大学名
    public String name;

    // 班级列表
    public List<Classes> classList;
}

6.在主函数写一个方法 
/**
     * 初始化数据
     */
    private void initData() {


        College college = new College();

        college.name = "科技大学";

        List<Classes> classesList = new ArrayList<>();

        for(int i = 1 ;i<3;i++) {
            Classes classes = new Classes();

            classes.name = "计算机"+i+"班";

            List<String> list = new ArrayList<>();

            list.add("mm");
            list.add("dd");
            classes.students = list;

            classesList.add(classes);
        }

        college.classList = classesList;


        colleges = new ArrayList<>();
        colleges.add(college);

    }


7.现在数据如下列所示
 
科技大学 
  • 计算机1班 
    • mm
    • dd
  • 计算机2班 
    • mm
    • dd

8.理解
ExpandableListView实现Listview折叠工具




9.外层适配器创建 
/**
 *
 * 外层ExpandListView 适配器的实现
 * Created by MH on 2016/6/16.
 */
public class SimpleExpandableListViewAdapter extends BaseExpandableListAdapter {


    // 大学的集合
    private List<College> colleges;

    private Activity activity;


    public SimpleExpandableListViewAdapter(List<College> colleges, Activity activity) {
        this.colleges = colleges;
        this.activity = activity;
    }

    @Override
    public int getGroupCount() {
        return colleges.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        // 很关键，，一定要返回  1
        return 1;
    }

    @Override
    public Object getGroup(int groupPosition) {
        return colleges.get(groupPosition);
    }

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return colleges.get(groupPosition).classList.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) {

        return getGenericView(colleges.get(groupPosition).name);
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

        // 返回子ExpandableListView 的对象  此时传入是该父条目，即大学的对象（有歧义。。）

        return getGenericExpandableListView(colleges.get(groupPosition));
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    private TextView getGenericView(String string) {
        AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);

        TextView textView = new TextView(activity);
        textView.setLayoutParams(layoutParams);

        textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);

        textView.setPadding(40, 20, 0, 20);
        textView.setText(string);
        textView.setTextColor(Color.RED);
        return textView;
    }


    /**
     *  返回子ExpandableListView 的对象  此时传入的是该大学下所有班级的集合。
     * @param college
     * @return
     */
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    public ExpandableListView getGenericExpandableListView(College college){
        AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);

        CustomExpandableListView view = new CustomExpandableListView(activity);

        // 加载班级的适配器
        ClassesExpandableListViewAdapter adapter = new ClassesExpandableListViewAdapter(college.classList,activity);

        view.setAdapter(adapter);

        view.setPadding(20,0,0,0);
        return view;
    }
}


代码依然一大串，但其实和之前写的ClassExpandableListViewAdapter都差不多一样，主要有以下几点区别：

  • getChildrenCount（） 返回1.
  • getChildView() 返回的是ExpandableListView对象。
  • getGenericExpandableListView()： 添加了获取ExpandableListView对象的方法。
可能在这里，观察仔细的会发现 getGenericExpandableListView() 中创建的是 CustomExpandableListView 对象，该对象是我自定义的。很多人可能都遇到过， ScrollView 嵌套 ListView ， ListView 显示不全。同样在这里也出现了， 子ExpandableListView 同样显示不全，所以自定义解决这个问题。




10.解决上面所述问题 
/**
 *
 * 自定义ExpandableListView  解决嵌套之下显示不全的问题
 * Created by MH on 2016/6/16.
 */
public class CustomExpandableListView extends ExpandableListView {


    public CustomExpandableListView(Context context) {
        super(context);
    }

    public CustomExpandableListView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public CustomExpandableListView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // 解决显示不全的问题
        int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2
                , MeasureSpec.AT_MOST);
        super.onMeasure(widthMeasureSpec, expandSpec);
    }
}


11.最后在主函数里面写

public class SimpleExpandListViewActivity extends AppCompatActivity {


    private ExpandableListView listview;

    private List<College> colleges;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_tree_view_simple);

        initData();

        // 查找控件
        listview = ((ExpandableListView) findViewById(R.id.tree_view_simple));


        SimpleExpandableListViewAdapter adapter = new SimpleExpandableListViewAdapter(colleges,this);

        // 设置适配器
        listview.setAdapter(adapter);
/*
        // 初始化数据
        List<Classes> classesList = new ArrayList<>();

        for(int i = 1 ;i<3;i++) {
            Classes classes = new Classes();

            classes.name = "计算机"+i+"班";

            List<String> list = new ArrayList<>();

            list.add("mm");
            list.add("dd");
            classes.students = list;

            classesList.add(classes);
        }*/

        // 构造适配器
       // ClassesExpandableListViewAdapter adapter = new ClassesExpandableListViewAdapter(classesList,this);





    }

    /**
     * 初始化数据
     */
    private void initData() {


        College college = new College();

        college.name = "科技大学";

        List<Classes> classesList = new ArrayList<>();

        for(int i = 1 ;i<3;i++) {
            Classes classes = new Classes();

            classes.name = "计算机"+i+"班";

            List<String> list = new ArrayList<>();

            list.add("mm");
            list.add("dd");
            classes.students = list;

            classesList.add(classes);
        }

        college.classList = classesList;


        colleges = new ArrayList<>();
        colleges.add(college);
    }
}



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