Question

How to print a HashMap with multiple values under the same key in Java

Answer 1

import java.util.HashMap;
import java.util.List;
 
public class User {
    public static void main(String args[]) {
        HashMap<String, List<String>> map = new HashMap<>();
         
        map.put("key1", List.of("value1", "value2", "value3", "value4"));
        map.put("key2", List.of("value5", "value6", "value7", "value8"));
 
        for (String key : map.keySet()) {
            System.out.println(key + ": ");
            for (String val :  map.get(key)) {
                System.out.println(val);
            }
        }
     }
}
     
     
     
     
/*
run:
     
key1: 
value1
value2
value3
value4
key2: 
value5
value6
value7
value8
   
*/

 

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Answer 2

import java.util.HashMap;
import java.util.List;

public class User {
    public static void main(String args[]) {
        HashMap<String, List<String>> map = new HashMap<>();
        
        map.put("key1", List.of("value1", "value2", "value3", "value4"));
        map.put("key2", List.of("value5", "value6", "value7", "value8"));

        for (String key : map.keySet()) {
            System.out.println(key + ": " + map.get(key));
        }
     }
}
    
    
    
    
/*
run:
    
key1: [value1, value2, value3, value4]
key2: [value5, value6, value7, value8]
  
*/

 

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Answer 3

import java.util.HashMap;

public class User {
    public static void main(String args[]) {
        HashMap<String, String[]> map = new HashMap<>();
        
        map.put("key1", new String[] {"value1", "value2", "value3", "value4"});
        map.put("key2", new String[] {"value5", "value6", "value7", "value8"});

        for (String key : map.keySet()) {
            System.out.println(key + ": " + String.join(", ", map.get(key)));
        }
     }
}
    
    
    
    
/*
run:
    
key1: value1, value2, value3, value4
key2: value5, value6, value7, value8
  
*/

 

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Answer 4

import java.util.HashMap;

public class User {
    public static void main(String args[]) {
        HashMap<String, String[]> map = new HashMap<>();
        
        map.put("key1", new String[] {"value1", "value2", "value3", "value4"});
        map.put("key2", new String[] {"value5", "value6", "value7", "value8"});

        for (String key : map.keySet()) {
            System.out.println(key + ": ");
            for (String val :  map.get(key)) {
                System.out.println(val);
            }
        }
     }
}
    
    
    
    
/*
run:
    
key1: 
value1
value2
value3
value4
key2: 
value5
value6
value7
value8
  
*/

 

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