如何在java中创建递归算法来创建树？

3 月，2 周 Questions & Answers 905

我有一个数据库表，其中的记录有StructureGuid和ParentGuid。所以大多数父母都有孩子

我想创建一个递归算法来构建树

树的类是Header.java：

public class Header implements MultiLevelExpIndListAdapter.ExpIndData {
  private List<Header> mChildren;
  private boolean mIsGroup;
  private int mGroupSize;

  public String header;
  public String structureGuid;

  public Header(String header, String guid){
    this.header = header;
    this.structureGuid = guid;
    mChildren = new ArrayList<Header>();
    setIndentation(0);
  }

  @Override public List<? extends MultiLevelExpIndListAdapter.ExpIndData> getChildren() {
    return mChildren;
  }

  @Override public boolean isGroup() {
    return mIsGroup;
  }

  @Override public void setIsGroup(boolean b) {
    mIsGroup = b;
  }

  @Override public void setGroupSize(int i) {
    mGroupSize = i;
  }

  public int getGroupSize() {
    return mGroupSize;
  }

  public void addChild(Header child){
    mChildren.add(child);
    child.setIndentation(getIndentation() + 1);
  }
}

我使用SQL框架获取根节点，然后循环遍历它们。停止情况是节点（Header）没有任何子节点

守则：

//Get the root nodes
public static List<Header> getHeaders(){
    List<Structure> list = new Select().from(Structure.class)
        .where(Condition.column(Structure$Table.PARENTGUID).eq(""))
        .and(Condition.column(Structure$Table.STATUS).eq(true))
        .and(Condition.column(Structure$Table.REQUIRED).eq(true))
        .orderBy("Sequence ASC").queryList();

    ArrayList<Header> headers = new ArrayList<>();
    for (Structure struct: list){
      headers.add(new Header(struct.getDescription(), struct.StructureGUID));
    }

    return addChildren(list, headers);
  }

//recursively return child nodes
  public static List<Header> addChildren(List<Structure> structures, List<Header> headers){
    List<Header> newHeader = new ArrayList<>();
    //recurring algorithm - while there are no kids get headers
    if(headers.size() > 0) {
      for (int i = 0; i < headers.size(); i++) {
        //get children of that header - if none return empty arraylist
        //else loop through and addChildren
        List<Structure> list = new Select().from(Structure.class)
            .where(Condition.column(Structure$Table.PARENTGUID).eq(headers.get(i).structureGuid))
            .and(Condition.column(Structure$Table.STATUS).eq(true))
            .and(Condition.column(Structure$Table.REQUIRED).eq(true))
            .orderBy("Sequence ASC").queryList();

        List <Header> temp = new ArrayList<Header>();

        Log.e("TAG", "size of array: " + list.size());

        if (list.size() != 0) {
          for (Structure struct : list) {
            headers.get(i).addChild(new Header(struct.getDescription(), struct.StructureGUID));
            temp.add(headers.get(i));
          }
        }
        newHeader = addChildren(list, temp);
      }
    }
    return newHeader;
  }

现在，它卡在第一个根节点的第一个子节点上的连续循环中

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如何在java中创建递归算法来创建树？

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