java - 使用java递归搜索Hashmap列表中的值

Question

我试图循环遍历 HashMap 列表并形成树状结构。输入( HashMap 列表)和所需的输出( HashMap 列表)如下:

输入:

[{State=Tamil Nadu, Continent=Asia, Country=India, City=Chennai}, {State=Kerala, Continent=Asia, Country=India, City=Cochin}, {State=Tamil Nadu, Continent=Asia, Country=India, City=Madurai}, {State=Something, Continent=Asia, Country=Srilanka, City=Colombo}, {State=anythig, Continent=Africa, Country=South Africa, City=new}]

预期结果:

[{children=[{children=[{State=Tamilnadu, children=[{City=Madurai}, {City=Chennai}]}, {State=Kerala, children=[{City=Cochin}]}], Country=India}, {Country=Srilanka}], Continent=Asia}, {Continent=Africa}]

(请考虑即使是斯里兰卡和非洲也应该具有相同的结构。我没有添加它，因为它是一个示例)

主要目标是形成如下树状结构:

  Asia
    India
      TamilNadu
        Chennai
        Madurai
      Kerala
        Cochin
    Srilanka
      Something
        Colombo
  Africa
    South Africa
      Anything
        new

所有数据都是动态的，唯一给定的输入是组顺序，如 "Continent, Country, State, City"这意味着城市属于州，州属于国家，依此类推。我在下面的代码中尝试的是搜索输入列表，首先获取城市，形成城市 map ，然后找到索引列表，其中 map 包含每个城市的值并获取州，将它们添加到一张 map 并添加该州对应的城市按键children (我想过以递归方式执行此操作，但无法得到一个想法)这很重要，因为 map 的最终列表将转换为树存储的 json 输入。这必须在java代码中完成，我对此感到震惊。任何人都可以提供示例或任何指示...

public void recursiveSearch(List<Map<String, String>> inputList){
    String groupOrder = "Continent, Country, State, City";
    String[] splitList = groupOrder.split(",");
    Map finalMap = new HashMap();
    for(int i= splitList.length-1; i >= 0; i--){
        //int index = 0;
        List searchList = new ArrayList();
        String keyToSearch= splitList[i].trim();
        for (Map<String, String> map : inputList) {

        String searchVal= map.get(keyToSearch);
        //index =  inputList.indexOf(map);
        //System.out.println(index);
        if(!searchList.contains(searchVal)){
            searchList.add(searchVal);
        }
        //System.out.println(searchVal);
    }
    if(searchList.size() > 0){
        Map allSearchMap = new HashMap();
        Map indSearchMap= new HashMap();
        for(int j=0; j < searchList.size(); j++ ){
            int index = 0;
            //System.out.println(splitList[splitList.length-1] +" "+ keyToSearch);
            if(((splitList[splitList.length-1]).trim()).equalsIgnoreCase(keyToSearch)){

              Map indexMap = new HashMap();
              for (Map<String, String> newMap : inputList) {

                    boolean result= newMap.containsValue(searchList.get(j));
                    if(result){
                        index =  inputList.indexOf(newMap);
                        System.out.println(searchList.get(j)+ " "+index);
                    }


                }
              indexMap.putAll(inputList.get(index));
              if(indexMap != null){
                  if(!indSearchMap.containsValue(searchList.get(j))){
                  indSearchMap.put(keyToSearch, searchList.get(j));
                  }
                  allSearchMap.put(keyToSearch+j, indSearchMap);
                  if(i-1 >= 0){
                  String parent = (String) indexMap.get(splitList[i-1].trim());

                  finalMap.put(splitList[i-1].trim(), parent);
                  finalMap.put("children", allSearchMap.get(keyToSearch+j));
                  //System.out.println(index+ " "+searchList.get(j)+" "+indexMap.get(splitList[i-1].trim()));
                  }
              }

            }



    }
}
}
System.out.println("--->"+finalMap.toString());

}

NOTE: The data and the group order are dynamic and can be of anything or any count.

Answer 1

试试这个

public class MyObjectClass implements Comparable<MyObjectClass> {

private String continent;
private String country;
private String state;
private String city;

public MyObjectClass(String continent) {
    this.continent = continent;
}

public String getContinent() {
    return continent;
}

public void setContinent(String continent) {
    this.continent = continent;
}

public String getCountry() {
    return country;
}

public void setCountry(String country) {
    this.country = country;
}

public String getState() {
    return state;
}

public void setState(String state) {
    this.state = state;
}

public String getCity() {
    return city;
}

public void setCity(String city) {
    this.city = city;
}

@Override
public int compareTo(MyObjectClass o) {
    if (this.continent.compareTo(o.continent) > 0)
        return 1;
    else if (this.continent.compareTo(o.continent) < 0)
        return -1;
    else
        return 0;

}
}

然后是我的主课。这将返回您的预期输出。

import java.util.*;

public class MyMain {
public static void main(String[] args) {

    List<MyObjectClass> list=new ArrayList<>();
    MyObjectClass myObj1=new MyObjectClass("Asia");
    myObj1.setCountry("Sri Lanka");
    myObj1.setState("Western");
    myObj1.setCity("Colombo");

    MyObjectClass myObj2=new MyObjectClass("Africa");
    myObj2.setCountry("South Africa");
    myObj2.setState("Anything");
    myObj2.setCity("new");

    MyObjectClass myObj3=new MyObjectClass("Asia");
    myObj3.setCountry("India");
    myObj3.setState("Tamil Nadu");
    myObj3.setCity("Chennai");

    MyObjectClass myObj4=new MyObjectClass("Asia");
    myObj4.setCountry("India");
    myObj4.setState("Kerala");
    myObj4.setCity("Cochin");

    list.add(myObj1);
    list.add(myObj2);
    list.add(myObj3);
    list.add(myObj4);

    Collections.sort(list);
    String tempCont=new String();
    String tempCount=new String();
    String tempState=new String();
    for(MyObjectClass i:list){
        if(tempCont.equals(i.getContinent())){
            if(tempCount.equals(i.getCountry())){
                if (tempState.equals(i.getState())){
                    System.out.println("-------------------------"+i.getCity());
                }
                else {
                    tempState=i.getState();
                    System.out.println("----------------"+tempState);
                    System.out.println("-------------------------"+i.getCity());
                }

            }
            else {
                tempCount=i.getCountry();
                System.out.println("--------"+tempCount);
                System.out.println("----------------"+i.getState());
                System.out.println("-------------------------"+i.getCity());
            }
        }
        else {
            tempCont=i.getContinent();
            System.out.println(tempCont);
            System.out.println("--------"+i.getCountry());
            System.out.println("----------------"+i.getState());
            System.out.println("-------------------------"+i.getCity());
        }

    }
}
 }