Java Collection, HashMap Exercises: Copy all of the mappings from the specified map to another map

Java Collection, HashMap Exercises: Exercise-3 with Solution

Write a Java program to copy all of the mappings from the specified map to another map.

Sample Solution:-

Java Code:

import java.util.*;  
public class Example3 {  
   public static void main(String args[]) {
  // create two hash maps
  HashMap <Integer,String> hash_map1 = new HashMap <Integer,String> ();
  HashMap <Integer,String> hash_map2 = new HashMap <Integer,String> ();
  // populate hash maps
  hash_map1.put(1, "Red");
  hash_map1.put(2, "Green");
  hash_map1.put(3, "Black");
  System.out.println("\nValues in first map: " + hash_map1);
  hash_map2.put(4, "White");
  hash_map2.put(5, "Blue");
  hash_map2.put(6, "Orange");
  System.out.println("\nValues in second map: " + hash_map2);

  // put all values in secondmap
  System.out.println("\nNow values in second map: " + hash_map2);

Sample Output:

Values in first map: {1=Red, 2=Green, 3=Black}                         
Values in second map: {4=White, 5=Blue, 6=Orange}                      
Now values in second map: {1=Red, 2=Green, 3=Black, 4=White, 5=Blue, 6=

Java Code Editor:

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Java: Tips of the Day


Counts the occurrences of a value in an array.

Use Arrays.stream().filter().count() to count total number of values that equals the specified value.

public static long countOccurrences(int[] numbers, int value) {
    return Arrays.stream(numbers)
            .filter(number -> number == value)

Ref: https://bit.ly/3kCAgLb