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Java Exercises: Generate random integers in a specific range

Java Numbers: Exercise-3 with Solution

Write a Java program to generate random integers in a specific range.

Pictorial Presentation:

Java: Generate random integers in a specific range

Sample Solution:

Java Code:

import java.util.Scanner;
public class Example3  {

      public static void main( String args[] ){ 
	    Scanner sc = new Scanner( System.in ); 
        System.out.print("Input the starting number of the range: "); 
        int rsnum = sc.nextInt(); 
        System.out.print("Input the ending number of the range: "); 
        int renum = sc.nextInt(); 
	    int random_num = rsnum + (int)(Math.random() * ((renum - rsnum) + 1));
	    System.out.println(random_num);
     }  
}

Sample Output:

Input the starting number of the range: 5                                                                     
Input the ending number of the range: 25                                                                      
10 

Flowchart:

Flowchart: Generate random integers in a specific range

Java Code Editor:

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Next: Write a Java program to generate and show all Kaprekar numbers less than 1000.

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH