Question

How to sort HashMap keys in ArrayList and keySet in Java

Answer 1

import java.util.Collections;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Set;

public class MyClass {
    public static void main(String args[]) {
        HashMap<String, Integer> hashmap = new HashMap<>();
  
        hashmap.put("java", 1);
        hashmap.put("c++", 2);
        hashmap.put("c", 3);
        hashmap.put("swift", 4);
        hashmap.put("python", 5);
        
        Set<String> set = hashmap.keySet();
        ArrayList<String> list = new ArrayList<String>();
        list.addAll(set);
        Collections.sort(list);

        for (String key : list) {
            System.out.println(key + " : " + hashmap.get(key));
        }
    }
}
  
  
  
  
/*
run:
  
c : 3
c++ : 2
java : 1
python : 5
swift : 4
  
*/

 

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