Android 开发中怎么利用TreeView实现一个多级树形列表

package com.example.androidtreeviewdemo.treeview;  public class Element {      private String contentText;      private int level;      private int id;      private int parendId;      private boolean hasChildren;      private boolean isExpanded;         public static final int NO_PARENT = -1;      public static final int TOP_LEVEL = 0;      public Element(String contentText, int level, int id, int parendId,       boolean hasChildren, boolean isExpanded) {     super();     this.contentText = contentText;     this.level = level;     this.id = id;     this.parendId = parendId;     this.hasChildren = hasChildren;     this.isExpanded = isExpanded;   }    public boolean isExpanded() {     return isExpanded;   }    public void setExpanded(boolean isExpanded) {     this.isExpanded = isExpanded;   }    public String getContentText() {     return contentText;   }    public void setContentText(String contentText) {     this.contentText = contentText;   }    public int getLevel() {     return level;   }    public void setLevel(int level) {     this.level = level;   }    public int getId() {     return id;   }    public void setId(int id) {     this.id = id;   }    public int getParendId() {     return parendId;   }    public void setParendId(int parendId) {     this.parendId = parendId;   }    public boolean isHasChildren() {     return hasChildren;   }    public void setHasChildren(boolean hasChildren) {     this.hasChildren = hasChildren;   } }