[英]Display ArrayList data in tree structure in java
I have an arrayList with following values: 我有一个带有以下值的arrayList:
static ArrayList<DTONodeDetail> tree;
public static void main(String[] args) {
// TODO Auto-generated method stub
tree=new ArrayList<DTONodeDetail>();
//first argument->NodeId
//second->NodeName
// third -> ParentNodeId
tree.add(getDTO(1,"Root",0));
tree.add(getDTO(239,"Node-1",1));
tree.add(getDTO(242,"Node-2",239));
tree.add(getDTO(243,"Node-3",239));
tree.add(getDTO(244,"Node-4",242));
tree.add(getDTO(245,"Node-5",243));
displayTree(tree.get(0));
}
public static DTONodeDetail getDTO(int nodeId,String nodeName,int parentID)
{
DTONodeDetail dto=new DTONodeDetail();
dto.setNodeId(nodeId);
dto.setNodeDisplayName(nodeName);
dto.setParentID(parentID);
return dto;
}
Now i want to display above data in tree structure as below using simple java code: 现在我想使用简单的Java代码在树状结构中显示以上数据:
Root
-----Node-1
------------Node-2
------------------Node-4
------------Node-3
------------------Node-5
I have tried following but unable to get desire result: 我尝试了以下操作,但无法获得期望的结果:
public static void displayTree(DTONodeDetail dto){
ArrayList<DTONodeDetail> childs = selectChild(dto.getNodeId());
System.out.println(dto.getNodeDisplayName());
for(DTONodeDetail obj:childs){
displayTree(obj);
}
}
public static ArrayList<DTOWorkSpaceNodeDetail> selectChild(int nodeID){
ArrayList<DTOWorkSpaceNodeDetail> list=new ArrayList<DTOWorkSpaceNodeDetail>();
for(int i=0;i<tree.size();i++)
{
if(tree.get(i).getParentID()==nodeID){
list.add(tree.get(i));
}
}
return list;
}
Please Provide some guide or code. 请提供一些指南或代码。
Sorry, I misunderstood the question. 抱歉,我误解了这个问题。 I updated them. 我更新了它们。
public class DTONodeDetail {
private int nodeId;
private String nodeName;
private int parentId;
public DTONodeDetail() {
}
public DTONodeDetail(int nodeId, String nodeName, int parentId) {
this.nodeId = nodeId;
this.nodeName = nodeName;
this.parentId = parentId;
}
public int getNodeId() {
return nodeId;
}
public void setNodeId(int nodeId) {
this.nodeId = nodeId;
}
public String getNodeName() {
return nodeName;
}
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public int getParentId() {
return parentId;
}
public void setParentId(int parentId) {
this.parentId = parentId;
}
private static List<DTONodeDetail> tree;
public static DTONodeDetail getDTO(int nodeId, String nodeName, int parentID) {
DTONodeDetail dto = new DTONodeDetail();
dto.setNodeId(nodeId);
dto.setNodeName(nodeName);
dto.setParentId(parentID);
return dto;
}
private static List<DTONodeDetail> selectChildren(int parentId) {
List<DTONodeDetail> result = new ArrayList<DTONodeDetail>();
for (DTONodeDetail d : tree) {
if (d.getParentId() == parentId) {
result.add(d);
}
}
return result;
}
public static void displayTree(DTONodeDetail dto, int level) {
List<DTONodeDetail> childs = selectChildren(dto.getNodeId());
String space = "";
for (int i = 0; i < level; i++) {
space += "\t";
}
System.out.println(space + dto.getNodeName());
if(childs.size()>0){
level ++;
}
for (DTONodeDetail obj : childs) {
displayTree(obj, level);
}
}
public static void main(String[] args) {
tree = new ArrayList<DTONodeDetail>();
tree.add(getDTO(1, "Root", 0));
tree.add(getDTO(239, "Node_1", 1));
tree.add(getDTO(242, "Node_2", 239));
tree.add(getDTO(243, "Node_3", 239));
tree.add(getDTO(244, "Node_4", 242));
tree.add(getDTO(245, "Node_5", 243));
displayTree(tree.get(0), 0);
}
}
Result: 结果:
Root
Node_1
Node_2
Node_4
Node_3
Node_5
The only problem with your implementation that I see, is that the output is as expected, but flat (ie no ----
at the beginning of child lines). 我看到的关于您的实现的唯一问题是,输出是预期的,但是是平坦的(即子行开头没有----
)。 This is because displayTree()
currently has no way of knowing at which level the node it is printing is. 这是因为displayTree()
当前无法知道它正在打印的节点处于哪个级别。
I propose this: 我建议:
public static void displayTree(DTONodeDetail dto, int charsBeforeNodename){
ArrayList<DTONodeDetail> childs = selectChild(dto.getNodeId());
for(int i = 0; i <= charsBeforeNodename; i++){
System.out.println("-");
}
System.out.println(dto.getNodeDisplayName());
for(DTONodeDetail obj:childs){
displayTree(obj, charsBeforeNodename + dto.getNodeDisplayName().length());
}
}
You should do like this 你应该这样
static void displayTree(DTONodeDetail root ,int level){
System.out.print(prefix(level));
System.out.println(root.name);
ArrayList<DTONodeDetail> children = selectChild(dto.getNodeId());
for(DTONodeDetail child : children){
displayTree(child, level + 1);
}
}
the prefix is a func to build enough '----' 前缀是一个足以构建“ ----”的函子
static String prefix(int level){
StringBuilder s = new StringBuilder();
for(int i = 0; i < level; i++){
s.append("----");
}
return s.toString();
}
Result 结果
displayTree(node1, 0);
Node-1
----Node-2
--------Node-4
----Node-3
--------Node-5
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