我有一堆父/子对,我想尽可能转变为分层树结构。例如,这些可能是配对:
Child : Parent
H : Ga
F : G
G : D
E : D
A : E
B : C
C : E
D : NULL
Z : Y
Y : X
X: NULL
需要将其转化为(a)层次结构树:
D
├── E
│ ├── A
│ │ └── B
│ └── C
└── G
| ├── F
| └── H
|
X
|
└── Y
|
└──Z
在Java中,我如何从包含child =>父对的arrayList转到像那样的Tree?
我需要这个操作的输出是arrayList包含两个元素D和X. 反过来,每个孩子都有孩子的名单,而孩子的名单又包含一个孩子的名单等等
public class MegaMenuDTO {
private String Id;
private String name;
private String parentId;
private List<MegaMenuDTO> childrenItems=new ArrayList<MegaMenuDTO>();
public String getId() {
return Id;
}
public void setId(String id) {
Id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getParentId() {
return parentId;
}
public void setParentId(String parentId) {
this.parentId = parentId;
}
public List<MegaMenuDTO> getChildrenItems() {
return childrenItems;
}
public void setChildrenItems(List<MegaMenuDTO> childrenItems) {
this.childrenItems = childrenItems;
}
}
我的第一次尝试是
private void arrangeMegaMenuTree(MegaMenuDTO grandParent,
MegaMenuDTO parent, List<MegaMenuDTO> children) {
for (MegaMenuDTO child : children) {
if (child.getParentId().equals(parent.getId())) {
arrangeMegaMenuTree(parent, child, children);
}
}
if (!grandParent.getId().equals(parent.getId())) {
grandParent.getChildrenItems().add(parent);
// children.remove(parent);
}
}
另一次尝试
private List<MegaMenuDTO> arrangeMegaMenuTree(MegaMenuDTOparent,List<MegaMenuDTO>menuItems) {
for (MegaMenuDTO child : menuItems) {
if (parent.getId().equals(child.getId())) {
continue;
}
if (hasChildren(child, menuItems)) {
parent.setChildrenItems(arrangeMegaMenuTree(child, menuItems
.subList(menuItems.indexOf(child), menuItems.size())));
} else {
List<MegaMenuDTO> tempList = new ArrayList<MegaMenuDTO>();
tempList.add(child);
return tempList;
}
}
return null;
}
private boolean hasChildren(MegaMenuDTO parent, List<MegaMenuDTO> children) {
for (MegaMenuDTO child : children) {
if (child.getParentId().equals(parent.getId())) {
return true;
}
}
return false;
}
答案 0 :(得分:6)
假设您的Node结构类似于:
Map<Object, Node> temp = new HashMap<>();
for (Pair pair: inputList) {
Node parent = temp.getOrDefault(pair.parent.id, new Node(pair.parent.id));
Node child = temp.getOrDefault(pair.child.id, new Node(pair.child.id));
parent.children.add(child);
child.parent = parent;
temp.put(parent.id, parent);
temp.put(child.id, child);
}
然后你首先开始迭代你的输入列表,并从ids-&gt;节点创建一个映射(这用于在树仍然是非结构化的情况下获取节点);
for (Node n: temp.values()) {
if (n.parent==null) {
root = n; break;
}
}
现在,您可以在地图上迭代搜索树的根
awk
此代码假定您的数据“有效”(没有重复的子条目,单根等)。否则您可以轻松地进行调整。
答案 1 :(得分:3)
这是基于第一个答案和问题更新的替代解决方案...... :)
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Main2 {
public static void main(String[] args) {
// input
ArrayList<Pair> pairs = new ArrayList<Pair>();
pairs.add(new Pair( "H" , "G"));
pairs.add(new Pair( "F" , "G"));
pairs.add(new Pair( "G" , "D"));
// ...
// Arrange
// String corresponds to the Id
Map<String, MegaMenuDTO> hm = new HashMap<>();
// you are using MegaMenuDTO as Linked list with next and before link
// populate a Map
for(Pair p:pairs){
// ----- Child -----
MegaMenuDTO mmdChild ;
if(hm.containsKey(p.getChildId())){
mmdChild = hm.get(p.getChildId());
}
else{
mmdChild = new MegaMenuDTO();
hm.put(p.getChildId(),mmdChild);
}
mmdChild.setId(p.getChildId());
mmdChild.setParentId(p.getParentId());
// no need to set ChildrenItems list because the constructor created a new empty list
// ------ Parent ----
MegaMenuDTO mmdParent ;
if(hm.containsKey(p.getParentId())){
mmdParent = hm.get(p.getParentId());
}
else{
mmdParent = new MegaMenuDTO();
hm.put(p.getParentId(),mmdParent);
}
mmdParent.setId(p.getParentId());
mmdParent.setParentId("null");
mmdParent.addChildrenItem(mmdChild);
}
// Get the root
List<MegaMenuDTO> DX = new ArrayList<MegaMenuDTO>();
for(MegaMenuDTO mmd : hm.values()){
if(mmd.getParentId().equals("null"))
DX.add(mmd);
}
// Print
for(MegaMenuDTO mmd: DX){
System.out.println("DX contains "+DX.size()+" that are : "+ mmd);
}
}
}
public class Pair {
private String childId ;
private String parentId;
public Pair(String childId, String parentId) {
this.childId = childId;
this.parentId = parentId;
}
public String getChildId() {
return childId;
}
public void setChildId(String childId) {
this.childId = childId;
}
public String getParentId() {
return parentId;
}
public void setParentId(String parentId) {
this.parentId = parentId;
}
}
import java.util.ArrayList;
import java.util.List;
public class MegaMenuDTO {
private String Id;
private String name;
private String parentId;
private List<MegaMenuDTO> childrenItems;
public MegaMenuDTO() {
this.Id = "";
this.name = "";
this.parentId = "";
this.childrenItems = new ArrayList<MegaMenuDTO>();
}
public String getId() {
return Id;
}
public void setId(String id) {
Id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getParentId() {
return parentId;
}
public void setParentId(String parentId) {
this.parentId = parentId;
}
public List<MegaMenuDTO> getChildrenItems() {
return childrenItems;
}
public void setChildrenItems(List<MegaMenuDTO> childrenItems) {
this.childrenItems = childrenItems;
}
public void addChildrenItem(MegaMenuDTO childrenItem){
if(!this.childrenItems.contains(childrenItem))
this.childrenItems.add(childrenItem);
}
@Override
public String toString() {
return "MegaMenuDTO [Id=" + Id + ", name=" + name + ", parentId="
+ parentId + ", childrenItems=" + childrenItems + "]";
}
}
答案 2 :(得分:2)
尝试一下
只需根据您的ID对其进行哈希处理即可建立关系。
完成后找到树的根。
private MegaMenuDTO getRoot(Map<String, MegaMenuDTO> tree) {
return tree.values().stream().filter(node -> Objects.isNull(node.getParentId())).findFirst().orElse(null);
}
public MegaMenuDTO createTree(List<MegaMenuDTO> list) {
Map<String, MegaMenuDTO> tree = new HashMap<>();
list.forEach(current -> tree.put(current.getId(), current));
list.forEach(current -> {
String parentId = current.getParentId();
if (tree.containsKey(parentId)) {
MegaMenuDTO parent = tree.get(parentId);
current.setParentId(parentId);
parent.addChildrenItem(current);
tree.put(parentId, parent);
tree.put(current.getId(), current);
}
});
return getRoot(tree);
}
答案 3 :(得分:0)
取决于@Diego Martinoia解决方案和@OSryx解决方案,我问题的最终解决方案
private List<MegaMenuDTO> dooo(List<MegaMenuDTO> input) {
Map<String, MegaMenuDTO> hm = new HashMap<String, MegaMenuDTO>();
MegaMenuDTO child = null;
MegaMenuDTO mmdParent = null;
for (MegaMenuDTO item : input) {
// ------ Process child ----
if (!hm.containsKey(item.getId())) {
hm.put(item.getId(), item);
}
child = hm.get(item.getId());
// ------ Process Parent ----
if (item.getParentId() != null && !item.getParentId().equals("")
&& !item.getParentId().equals("0")) {
if (hm.containsKey(item.getParentId())) {
mmdParent = hm.get(item.getParentId());
mmdParent.getChildrenItems().add(child);
}
}
}
List<MegaMenuDTO> DX = new ArrayList<MegaMenuDTO>();
for (MegaMenuDTO mmd : hm.values()) {
if (mmd.getParentId() == null || mmd.getParentId().equals("")
|| mmd.getParentId().equals("0"))
DX.add(mmd);
}
return DX;
}
答案 4 :(得分:0)
这是我的解决方法:
将MegaMenuDTO列表转换为地图:
this.$('.add-resource').click(function () {
var testId = $(this).attr('id');
//alert(testId);
$("#layoutCanvas").find(`[data-id='${testId}']`).addClass('hidden')
});
然后将地图转换为树:
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
<a class="btn btn-primary add-resource" id="567">Button</a>
<div id="layoutCanvas">
<div data-id="567">
Test 1
</div>
<div data-id="235">
Test 2
</div>
</div>
<style>
.hidden{
//attribute you want to add
}
</style>