root@generate-random:~/numbers/java$ _

Generate Random Numbers in Java

Complete code tutorial with examples and best practices

PHP JavaScript Python

Java

C# C++ Ruby Go

[ Code Example - Quick Summary ]

Language: Java

What: Generate random numbers in Java using the <code>Random</code> class, <code>ThreadLocalRandom</code> for better performance, or <code>SecureRandom</code> for cryptographically secure random numbers.

Try it: Use our interactive Numbers generator or integrate this code into your Java application.

Generate random numbers in Java using the Random class, ThreadLocalRandom for better performance, or SecureRandom for cryptographically secure random numbers. Looking for other languages? Check our code examples in PHP , JavaScript , Python , C# , C++ , Ruby and Go or use our interactive web generator.

Java Code Example

import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.security.SecureRandom;
import java.util.stream.IntStream;

public class RandomNumberExample {
    public static void main(String[] args) {
        // Generate a single random number between 1 and 100
        Random random = new Random();
        int randomNumber = random.nextInt(100) + 1;
        System.out.println(randomNumber);  // Example output: 42

        // Generate multiple random numbers (Java 8+)
        int[] numbers = IntStream.generate(() ->
            ThreadLocalRandom.current().nextInt(1, 101)
        ).limit(10).toArray();

        System.out.println(java.util.Arrays.toString(numbers));
        // Example output: [23, 7, 91, 45, 12, 68, 3, 89, 54, 31]

        // Generate cryptographically secure random number
        SecureRandom secureRandom = new SecureRandom();
        int secureNumber = secureRandom.nextInt(100) + 1;
        System.out.println(secureNumber);  // Example: 67

        // Random double between 0 and 100
        double randomDouble = random.nextDouble() * 100;
        System.out.printf("%.2f%n", randomDouble);  // Example: 42.17
    }
}

[EXPLANATION]

Random.nextInt(n) returns a value from 0 (inclusive) to n (exclusive), so add your minimum value. ThreadLocalRandom is preferred for concurrent applications as it reduces contention. SecureRandom provides cryptographically strong random numbers but is slower.

Expected Output

42
[23, 7, 91, 45, 12, 68, 3, 89, 54, 31]
67
42.17

Common Use Cases

Enterprise application random data generation
Android app development (random features)
Cryptographic token and key generation with SecureRandom
Multi-threaded applications using ThreadLocalRandom
Game development and simulation engines
JUnit test data generation

Important Notes

Use ThreadLocalRandom for better performance in concurrent code
SecureRandom is thread-safe but slower
Java 8+ streams provide elegant syntax for multiple randoms
Random can be seeded for reproducible results

Try Our Interactive Generator

Don't want to write code? Use our free web-based Numbers generator with instant results.

TRY NUMBERS GENERATOR →

Other Programming Languages

PHP $ view --lang=php

View Numbers generation code examples in PHP

JAVASCRIPT $ view --lang=javascript

View Numbers generation code examples in JavaScript

PYTHON $ view --lang=python

View Numbers generation code examples in Python

C# $ view --lang=csharp

View Numbers generation code examples in C#

C++ $ view --lang=cpp

View Numbers generation code examples in C++

RUBY $ view --lang=ruby

View Numbers generation code examples in Ruby

GO $ view --lang=go

View Numbers generation code examples in Go