Syntax error How to track the order of insertion using Java collections?

How to track the order of insertion using Java collections?

To track the order of insertion, you can use Map.Entry() in case of a Map. Let’s say we have the following LinkedHashMap −

Map<String, Integer>map = new LinkedHashMap<>();
map.put("Jack", 0);
map.put("Tim", 1);
map.put("David", 2);
map.put("Tom", 3);
map.put("Kevin", 4);
map.put("Jeff", 5);

Now, loop through Map.Entry and get the order of insertion correctly with Key and Value −

for (Map.Entry<String, Integer>entry: map.entrySet()) {
   System.out.println(entry.getKey() + " => " + entry.getValue());
}

Example

 Live Demo

import java.util.LinkedHashMap;
import java.util.Map;
public class Demo {
   public static void main(String[] args) {
      Map<String, Integer>map = new LinkedHashMap<>();
      map.put("Jack", 0);
      map.put("Tim", 1);
      map.put("David", 2);
      map.put("Tom", 3);
      map.put("Kevin", 4);
      map.put("Jeff", 5);
      map.put("Katies", 6);
      map.put("Steve", 7);
      map.put("Andrew", 8);
      map.put("Angelina", 9);
      for (Map.Entry<String, Integer>entry: map.entrySet()) {
         System.out.println(entry.getKey() + " => " + entry.getValue());
      }
   }
}

Output

Jack => 0
Tim => 1
David => 2
Tom => 3
Kevin => 4
Jeff => 5
Katies => 6
Steve => 7
Andrew => 8
Angelina => 9
Updated on: 2019-07-30T22:30:25+05:30

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