Java Random.doubles() – Syntax & Examples

Java Random.doubles() – Examples

In this tutorial, we will learn about the Java Random.doubles() method, and learn how to use this method to generate a stream of pseudorandom double values, with the help of examples.

doubles()

Random.doubles() returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

Syntax

The syntax of doubles() method is

Random.doubles()

Returns

The method returns DoubleStream object.

Example 1 – doubles()

In this example, we will generate an unlimited sequence of random double-precision floating point numbers using doubles() method and print out four of them to the console.

Java Program

import java.util.Random;
import java.util.function.DoubleConsumer;
import java.util.stream.DoubleStream;  

public class Example {  
	public static void main(String[] args) {  
		Random random = new Random();  
		DoubleStream ds = random.doubles();  

		ds.limit(4).forEach(new DoubleConsumer() {
			@Override
			public void accept(double value) {
				System.out.println(value);
			}
		});
    }  
}

Output

0.14584589858798724
0.01596337682890825
0.4461234706535546
0.5966428933676975

doubles(randomNumberOrigin, randomNumberBound)

Random.doubles() returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Syntax

The syntax of doubles() method with random number origin and random number bound is

Random.doubles(double randomNumberOrigin, double randomNumberBound)

where

Parameter	Description
randomNumberOrigin	The origin (inclusive) of each random value.
randomNumberBound	The bound (exclusive) of each random value.

Returns

The method returns DoubleStream object.

Example 2 – doubles(randomNumberOrigin, randomNumberBound)

In this example, we will generate an unlimited sequence of random double-precision floating point numbers, which are limited by an origin and bound using doubles() method and print out four of these numbers from the stream to the console.

Java Program

import java.util.Random;
import java.util.function.DoubleConsumer;
import java.util.stream.DoubleStream;  

public class Example {  
	public static void main(String[] args) {  
		double randomNumberOrigin = 1;  
		double randomNumberBound = 7;  
		Random random= new Random();  
		DoubleStream ds = random.doubles(randomNumberOrigin, randomNumberBound);  
 
		ds.limit(4).forEach(new DoubleConsumer() {
			@Override
			public void accept(double value) {
				System.out.println(value);
			}
		});
    }  
}  

Output

4.124126976639339
6.277075813743702
2.9896554435576643
1.6867903457923643

doubles(long streamSize)

Random.doubles() returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

Syntax

The syntax of doubles() method with stream size is

Random.doubles(long streamSize)

where

Parameter	Description
streamSize	The number of values to generate in the stream.

Returns

The method returns DoubleStream object.

Example 3 – doubles(streamSize)

In this example, we will generate an specific number of random double-precision floating point numbers, using doubles(streamSize) method and print out these random numbers from the stream to the console.

Java Program

import java.util.Random;
import java.util.function.DoubleConsumer;
import java.util.stream.DoubleStream;  

public class Example {  
	public static void main(String[] args) {  
		long streamSize = 5;  
		Random random = new Random();
		DoubleStream ds = random.doubles(streamSize);
		
		ds.forEach(new DoubleConsumer() {
			@Override
			public void accept(double value) {
				System.out.println(value);
			}
		});
    }  
} 

Output

0.24585762538765643
0.8752279248291293
0.6706517385958398
0.47129774709285743
0.8528845262464368

doubles(streamSize, randomNumberOrigin, randomNumberBound)

Random.doubles() returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Syntax

The syntax of doubles() method with stream size, random number origin and random number bound is

Random.doubles(long streamSize, double randomNumberOrigin, double randomNumberBound)

where

Parameter	Description
streamSize	The number of values to generate in the Stream.
randomNumberOrigin	The origin (inclusive) of each random value in the Stream.
randomNumberBound	The bound (exclusive) of each random value in the Stream.

Returns

The method returns DoubleStream object.

Example 4 – doubles(streamSize, randomNumberOrigin, randomNumberBound)

In this example, we will generate eight random double-precision floating point numbers which are limited by an origin and bound using doubles() method and print out these random numbers from the stream to the console.

Java Program

import java.util.Random;
import java.util.function.DoubleConsumer;
import java.util.stream.DoubleStream;  

public class Example {  
	public static void main(String[] args) {  
		double randomNumberOrigin = 1;  
		double randomNumberBound = 7;  
		long streamSize = 8;  
		Random random = new Random();
		DoubleStream ds =random.doubles(streamSize,randomNumberOrigin,randomNumberBound);  
		
		ds.forEach(new DoubleConsumer() {
			@Override
			public void accept(double value) {
				System.out.println(value);
			}
		});
    }  
}

Output

2.392701685665302
2.9381978153219777
3.69356795462521
6.0812621302928305
5.793783278818572
5.451979737142773
1.8253898408924665
2.54037873488756

Conclusion

In this Java Tutorial, we have learnt the syntax of Java Random.doubles() method, and also learnt how to use this method with the help of Java examples.