I am trying to get the first name of a linkedhashmap but its only spitting out the last one.

This is my hashmap, Im only getting the last name printed out. How do I get the first one? Is there a way to get it linked to the key. For example "gumt" prints out Gumtäkts uni.bibliotek?

LinkedHashMap<String,Node> nodes = new LinkedHashMap<>();

nodes.put("gumt", new Node("Gumtäkts uni.bibliotek   ", 60.2039, 24.9638));
nodes.put("lill", new Node("Lillhoplax bibliotek     ", 60.2008, 24.8954));
nodes.put("bush", new Node("Busholmens bibliotek     ", 60.1593, 24.9207));

for (String key : nodes.keySet()) {

           
           nodes.get(key).setKey(key);

           System.out.println("["   key   "]"   " "   nodes.get(key).getName());
}
return nodes;

Output:

[gumt] Busholmens bibliotek     
[lill] Busholmens bibliotek 
[bush] Busholmens bibliotek

I also have a Node class that comes into effect. Node class:

import java.util.ArrayList;

public class Node{

    private static String name;
    private static String key;
    private double latitude;
    private double longitude;
    private static ArrayList<Node> neighbours;

    public Node(String name, double latitude, double longitude) {


        this.name = name;
        this.key = key;
        this.latitude = latitude;
        this.longitude = longitude;
        this.neighbours = neighbours;
    }

    public static String getName() {

        return name;
        }

    public static String getKey(){

        return key;
    }

    public void setName(String name){

        this.name = name;
    }

    public void setKey(String name){

        this.key = key;
    }

    public void addNeighbour(Node neighbour){

        this.neighbours = neighbours;
    }

    public static ArrayList<Node> getNeighbours(){

        return neighbours;
    }

    }

CodePudding user response：

Try using entrySet() instead of keySet():

for (Map.Entry<String, Node> entry : nodes.entrySet()) {
    String key = entry.getKey();
    Node node = entry.getValue();
    System.out.println("["   key   "] "   node.getName());
}

CodePudding user response：

A second association map can be created to keep track the order of elements inserted.

public class TestFirst {

    public static void main(String[] args)
    {
        Main m = new TestFirst().new Main();
        System.out.println(m.nodes.get(m.map.get(1)));
        System.out.println(m.nodes.get(m.map.get(3)));
    }
    
    class Main
    {
        int counter=0;
        LinkedHashMap<String,Node> nodes = new LinkedHashMap<>();
        Map <Integer, String> map = new HashMap<>();
        Main()
        {
            nodes.put("gumt", new Node("Gumtäkts uni.bibliotek   ", 60.2039, 24.9638));
            map.put(incCounter(), "gumt");
            nodes.put("lill", new Node("Lillhoplax bibliotek     ", 60.2008, 24.8954));
            map.put(incCounter(), "lill");
            nodes.put("bush", new Node("Busholmens bibliotek     ", 60.1593, 24.9207));
            map.put(incCounter(),"bush");
        }
        public int incCounter()
        {
            return   counter;
        }
        class Node
        {
            private String name;
            private String key;
            private double latitude;
            private double longitude;
            private ArrayList<Node> neighbours;

            public Node(String name, double latitude, double longitude) {


                this.name = name;
                this.key = key;
                this.latitude = latitude;
                this.longitude = longitude;
                this.neighbours = neighbours;
            }

            public String toString()
            {
                return name "(" latitude "," longitude ")";
            }
            public String getName() {
                return name;
                }
            
            public String getKey(){
                return key;
            }

            public void setName(String name){
                this.name = name;
            }

            public void setKey(String name){
                this.key = key;
            }

            public void addNeighbour(Node neighbour){
                this.neighbours = neighbours;
            }

            public ArrayList<Node> getNeighbours(){
                return neighbours;
            }

          }

    }
}

Output:

Gumtäkts uni.bibliotek   (60.2039,24.9638)
Busholmens bibliotek     (60.1593,24.9207)

Note: Check also the modifiers: static.

CodePudding user response：

System.out.println("["   key   "]"   " "   nodes.get(key).getName())

In this line you are trying to print the values, which are linked to the keys i suppose. But, the getName() function in the class node, only returns the name attribute of nodes, which in your case is always the same, because the field name is defined as static in your class Node