- Java Basic Programs
- Java Programming Examples
- Java Print Hello World
- Java Get Input from User
- Java Print Integer
- Java Add two Numbers
- Java Check Even or Odd
- Java Check Prime or Not
- Java Check Alphabet or Not
- Java Check Vowel or Not
- Check Reverse equal Original
- Java Fahrenheit to Celsius
- Java Celsius to Fahrenheit
- Java Perfect Number Program
- Java Find Quotient Remainder
- Java Days to Seconds
- Java Count Digits in Number
- Java Binary Number Addition
- Java Discount Program
- Java Compute Courier Charge
- Java Find Telephone Bill
- Java Print ASCII Values
- Java Check Palindrome or Not
- Java Check Armstrong or Not
- Generate Armstrong Numbers
- Add two Numbers using Pointers
- Java Mathematical Programs
- Add Subtract Multiply & Divide
- Java Make Calculator
- Java Add Digits of Number
- Java Check Leap Year or Not
- Java Check Divisibility
- Java Find Simple Interest
- Java Find Compound Interest
- Java Print Fibonacci Series
- Java Find nCr nPr
- Calculate Average & Percentage
- Java Calculate Arithmetic Mean
- Java Calculate Student Grade
- Java Print Table of Number
- Java Print Prime Numbers
- Java Add n Numbers
- Java Interchange two Numbers
- Java Reverse Numbers
- Java Swap two Numbers
- Count Positive Negative & Zero
- Find Largest of two Numbers
- Find Largest of three Numbers
- Java Find Factorial of Number
- Java Find HCF & LCM
- Area & Perimeter of Square
- Area & Perimeter of Rectangle
- Area & Circumference of Circle
- Java Conversion Programs
- Java Decimal to Binary
- Java Decimal to Octal
- Java Decimal to Hexadecimal
- Java Binary to Decimal
- Java Binary to Octal
- Java Binary to Hexadecimal
- Java Octal to Decimal
- Java Octal to Binary
- Java Octal to Hexadecimal
- Java Hexadecimal to Decimal
- Java Hexadecimal to Binary
- Java Hexadecimal to Octal
- Java Pattern Programs
- Java Pattern of Stars
- Java Pattern of Alphabets
- Java Pattern of Numbers
- Java Pyramid of Stars
- Java Pyramid of Alphabets
- Java Pyramid of Numbers
- Java Print Diamond Pattern
- Java Print Floyd Triangle
- Java Print Pascal Triangle
- Java Array Programs
- One Dimensional Array Program
- Java Linear Search
- Java Binary Search
- Find Largest Element in Array
- Find Smallest Element in Array
- Java Reverse Array
- Insert Element in Array
- Delete Element from Array
- Java Merge two Array
- Java Bubble Sort
- Java Selection Sort
- Java Insertion Sort
- Java Find Common Elements
- Java Count Even/Odd Number
- Two Dimensional Array Program
- Java Add two Matrices
- Java Subtract two Matrices
- Java Transpose Matrix
- Multiply two Matrices
- Three Dimension Array Program
- Java String Programs
- Java Print String
- Find Length of String
- Java Compare two String
- Java Copy String
- Java Concatenate String
- Java Reverse String
- Delete Vowels from String
- Delete Words from Sentence
- Find Occurrence of a Character
- Java Find Occurrence of a Word
- Occurrence of Each Character
- Java Occurrence of Each Word
- Java Count Repeated Characters
- Java Count Repeated Words
- Java Capitalize Each Word
- Java Count Vowels/Consonants
- Java Extract Numbers
- Java Count Word in String
- Remove Spaces from String
- Java Sort a String
- Java Uppercase to Lowercase
- Java Lowercase to Uppercase
- Java Swap two Strings
- Java Check Anagram or Not
- Java Check Balance Parentheses
- Java Check Password Strength
- Java File Programs
- Java Read File
- Java Write to File
- Read & Display File Content
- Java Copy File
- Java Append Text to File
- Java Merge two File
- List files in Directory
- Java Delete File
- Java Miscellaneous Programs
- Generate Random Numbers
- Java Print Time & Date
- Java Get IP Address
- Java Shutdown Computer
- Java Programming Tutorial
- Java Tutorial
Java Program to Generate Random Numbers
This article is created to cover multiple programs in Java that generate and prints random number(s). Here are the list of programs covered in this article:
- Generate and print a random number in Java using Math.random()
- Generate and print n random numbers in Java
- Generate and print n random numbers between 1 to 100 in Java
- Generate and print n random numbers between given range in Java
- Generate and print random numbers in Java using Random class
Generate and Print a Random Number in Java
The question is, write a Java program to generate a random number. The program given below is its answer:
import java.lang.Math; public class fresherearth { public static void main(String[] args) { double num = Math.random(); System.out.println("Random Number = " +num); } }
The snapshot given below shows the sample output produced by above Java program:
Every time you execute the above program, there would be a different random number generated.
Note - Since the random number returned by Math.random() is of double type, therefore I've stored the returned random number in a variable of double type. You can use other like float, but you need to typecast, to avoid loosy conversion from double to float.
Generate and Print n Random Numbers in Java
Since previous program generate and prints only one random number at a time. Therefore, let's allow user to define the amount of random numbers to generate, then print, using the program given below:
import java.util.Scanner; import java.lang.Math; public class fresherearth { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.print("How many random numbers to generate ? "); int n = scan.nextInt(); System.out.println("\nList of " +n+ " Random Numbers:"); for(int i=0; i<n; i++) System.out.println(Math.random()); } }
The sample run with user input 7 is shown in the snapshot given below:
Generate Random Numbers between 1 to 100 in Java
If you've not noticed, then let me tell you, that the Math.random() are generating random numbers between 0 to 1. Therefore to generate random numbers between 1 to 100, we need to use the program given below.
import java.util.Scanner; import java.lang.Math; public class fresherearth { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.print("How many random numbers to generate ? "); int n = scan.nextInt(); System.out.println("\n" +n+ " Random Numbers between 1 to 100 are:"); for(int i=0; i<n; i++) { double num = Math.random()*(100); System.out.println(num); } } }
The sample run of above program with user input 15 is shown in the snapshot given below:
Generate Random Numbers between 1 to 10 - Whole Number
Since previous program generates random numbers that are of double type. Therefore to generate random numbers of int type, a whole number, then use following program:
import java.util.Scanner; import java.lang.Math; public class fresherearth { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.print("Enter the Value of n: "); int n = scan.nextInt(); System.out.println("\n---" +n+ " Random Numbers between 1 to 10---"); for(int i=0; i<n; i++) { double num = Math.random()*(10); int wholeNum = (int)num; System.out.print(wholeNum+ " "); } } }
Here is its sample run with same user input as of previous program:
Generate Random Numbers between Given Range in Java
This program generates n random numbers between given range. The value of n and the range are all received by user at run-time of the program:
import java.util.Scanner; import java.lang.Math; public class fresherearth { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.print("Enter the Value of n: "); int n = scan.nextInt(); System.out.print("Enter the Range: "); int start = scan.nextInt(); int end = scan.nextInt(); System.out.println("\n--"+n+" Random Numbers between "+start+" and "+end+"--"); for(int i=0; i<n; i++) { double num = Math.random()*(end-start+1)+start; int wholeNum = (int)num; System.out.print(wholeNum+ " "); } } }
The snapshot given below shows the sample run of above program, with user input 15 as size, 50 as starting number and 60 as ending number, to generate 15 random numbers between 50 to 60:
Generate Random Numbers in Java using Random Class
This is the last program of this article, created using Random class to generate random numbers, instead of Math.random()
import java.util.Random; public class fresherearth { public static void main(String[] args) { Random r = new Random(); System.out.println("10 Random Numbers from 0 to 4"); for(int i=0; i<10; i++) System.out.println(r.nextInt(5)); } }
The output produced by above Java program is:
10 Random Numbers from 0 to 4 3 3 1 2 3 4 4 1 0 1
Same Program in Other Languages
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