Alternative, use custom Pair class that implements Comparable.

class Pair implements Comparable<Pair> {
    Integer value;
    Integer index;

    public Pair(Integer value, Integer index) {
        this.value = value;
        this.index = index;
    }

    @Override
    public int compareTo(Pair o) {
        return value - o.value;
    }
}

and then usage

// Add elements
queue.add(new Pair(valueKey, index));
// do it for all your elements

final Pair min = queue.poll();
Integer index = min.index;
Integer value = min.value;

// Do with them what you want.

I used PriorityQueue in leetcode challenge. https://leetcode.com/problems/merge-k-sorted-lists/discuss/630580/Using-PriorityQueue-in-Java

And this is full example https://github.com/yan-khonski-it/leetcode/blob/master/src/main/java/com/yk/training/leetcode/merge_sorted_lists/PriorityQueueSolution.java

In Java you can use a HashMap for that:

import javafx.util.Pair;
import java.util.PriorityQueue;

public class YourClass{

    public static void main (String[] args){

        int n = 3;

PriorityQueue<Pair<Integer,Integer> > pq = new PriorityQueue<Pair<Integer,Integer>>(n, Comparator.comparing(Pair::getKey));

  /*Adding elements to HashMap*/
  pq.add(new Pair <> (10, 200));
  pq.add(new Pair <> (20, 100));
  pq.add(new Pair <> (15, 400));

 System.out.println(l.poll().getValue()); 
    }
}
 

Below is the Dijkstra implementation using priority_queue . Here ignore the InputReader class as it is for fast input . We can maintain priority according to "Value" of pair in key value pair . Then choose the Pair with minimum cost i.e value .

import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.List;
import java.util.PriorityQueue;
/** 
 * By: Rajan Parmar
 * At : HackerRank 
 **/
public class Dijkstra { 
     // node ,pair ( neighbor , cost)
    static HashMap < Integer , HashSet <Pair>> node;
    static PrintWriter w;   
    public static void main(String [] s) throws Exception{
        InputReader in;

        boolean online = false;
        String fileName = "input";

        node = new HashMap<Integer, HashSet<Pair>>();


        //ignore online if false it is for online competition
        if (online) {

            //ignore
            in = new InputReader(new FileInputStream(
                    new File(fileName + ".txt")));
            w = new PrintWriter(new FileWriter(fileName + "Output.txt"));
        } else {

            // for fast input output . You can use any input method
            in = new InputReader(System.in);
            w = new PrintWriter(System.out);
        }

        // Actual code starts here
        int t;
        int n, m;
        t = in.nextInt();

        while(t-- > 0){
            n = in.nextInt();
            m = in.nextInt();
            while(m-- > 0){
                int x,y,cost;
                x = in.nextInt();
                y = in.nextInt();
                cost = in.nextInt();

                if(node.get(x)==null){
                    node.put(x, new HashSet());
                    node.get(x).add(new Pair(y,cost));
                }
                else{
                    node.get(x).add(new Pair(y,cost));
                }
                if(node.get(y)==null){
                    node.put(y, new HashSet());
                    node.get(y).add(new Pair(x,cost));
                }
                else{
                    node.get(y).add(new Pair(x,cost));
                }
            }
            int source = in.nextInt();
            Dijkstra(source,n);
            node.clear();
            System.out.println("");
        }
    }

    static void Dijkstra(int start , int n) {

        int dist[] = new int[3001];
        int visited[] = new int[3001];
        Arrays.fill(dist, Integer.MAX_VALUE);
        Arrays.fill(visited, 0);
        dist[start] = 0 ;
        PriorityQueue < Pair > pq = new PriorityQueue();

        //this will be prioritized according to VALUES (i.e cost in class Pair)
        pq.add(new Pair(start , 0));
        while(!pq.isEmpty()){
            Pair pr = pq.remove();
            visited[pr.neighbor] = 1;
            for(Pair p:node.get(pr.neighbor)){
                if(dist[p.neighbor] > dist[pr.neighbor] + p.cost){
                    dist[p.neighbor] = dist[pr.neighbor] + p.cost;

                    //add updates cost to vertex through start vertex
                    if(visited[p.neighbor]==0)
                        pq.add(new Pair(p.neighbor ,dist[p.neighbor] ));
                }

            }
        }
        for(int i=1;i<=n;i++){
            if(i==start) continue;
            if(visited[i]==0)
                dist[i]=-1;
            System.out.print(dist[i]+" ");
        }
    }

    static class Pair implements Comparable {

        int neighbor;
        int cost;

        public Pair(int y, int cost) {
            // TODO Auto-generated constructor stub
            neighbor = y;
            this.cost = cost;
        }

        @Override
        public int compareTo(Object o) {
            // TODO Auto-generated method stub
            Pair pr = (Pair)o;

            if(cost > pr.cost)
                return 1;
            else
                return -1;

        }

    }

    //Ignore this class , it is for fast input.
    static class InputReader {

        private InputStream stream;
        private byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int snext() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = snext();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nextLong() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = snext();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int[] nextIntArray(int n) {
            int a[] = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        public String readString() {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = snext();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }
}

This will take input in following format .

First line be T (no. of test case).

For each test case next line input will be N and M , where N is no of nodes , M is no of edges.

Next M line contains 3 integers i.e x,y,W. It represents edge between node x and y with weight W.

Next line contain single integer i.e. Source node .

Output :

Print shortest distance to all node from given source node . If node is unreachable print -1.

e.g

Input :

1
6 8
1 2 1
1 5 4
2 5 2
2 3 2
5 6 5
3 6 2
3 4 1
6 4 3
1

Output : (shortest distance of all node from node 1)

1 3 4 3 5

You can also use lambda like this if you don't want Pair class to implement Comparator interface

PriorityQueue<Pair> queue = new PriorityQueue<>(5, (p1, p2) -> Float.compare(p1.getX(), p2.getX()));

For reverse order:

PriorityQueue<Pair> queue = new PriorityQueue<>(5, (p1, p2) -> Float.compare(p2.getX(), p1.getX()));

If you prefer your comparison logic in a static factory method or utility function, you can use something like this:

PriorityQueue<Pair> queue = new PriorityQueue<>(NodeUtil::customCompare);

public static int customCompare(Pair p1, Pair p2) {
  return Float.compare(p1.getX(), p2.getX());
}