Random class sample program in Java - nextGaussian(), nextBoolean(), nextBytes(), nextInt(), nextLong(), nextFloat(), nextDouble()

By: Manoj Kumar Emailed: 1768 times Printed: 2516 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

The Random class is a generator of pseudorandom numbers. These are called pseudorandom numbers because they are simply uniformly distributed sequences. Random defines the following constructors:

Random( )
Random(long seed)

The first version creates a number generator that uses the current time as the starting, or seed, value. The second form allows you to specify a seed value manually.

If you initialize a Random object with a seed, you define the starting point for the random sequence. If you use the same seed to initialize another Random object, you will extract the same random sequence. If you want to generate different sequences, specify different seed values. The easiest way to do this is to use the current time to seed a Random object. This approach reduces the possibility of getting repeated sequences.

There are six types of random numbers that you can extract from a Random object. Random Boolean values are available from nextBoolean(). Random bytes can be obtained by calling nextBytes(). Integers can be extracted via the nextInt() method. Long integers, uniformly distributed over their range, can be obtained with nextLong(). The nextFloat() and nextDouble() methods return a uniformly distributed float and double, respectively, between 0.0 and 1.0. Finally, nextGaussian() returns a double value centered at 0.0 with a standard deviation of 1.0. This is what is known as a bell curve.

Here is an example that demonstrates the sequence produced by nextGaussian(). It obtains 100 random Gaussian values and averages these values. The program also counts the number of values that fall within two standard deviations, plus or minus, using increments of 0.5 for each category. The result is graphically displayed sideways on the screen.

// Demonstrate random Gaussian values.
import java.util.Random;
class RandDemo {
public static void main(String args[]) {
Random r = new Random();
double val;
double sum = 0;
int bell[] = new int[10];
for(int i=0; i<100; i++) {
val = r.nextGaussian();
sum += val;
double t = -2;
for(int x=0; x<10; x++, t += 0.5)
if(val < t) {
bell[x]++;
break;
}
}
System.out.println("Average of values: " +
(sum/100));
// display bell curve, sideways
for(int i=0; i<10; i++) {
for(int x=bell[i]; x>0; x—)
System.out.print("*");
System.out.println();
}
}
}

Here is a sample program run. As you can see, a bell-like distribution of numbers is obtained.

Average of values: 0.0702235271133344
**
*******
******
***************
******************
*****************
*************
**********
********
***


Java Home | All Java Tutorials | Latest Java Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(0)


Be the first one to add a comment

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Manoj Kumar
Importing Keystore example using keytool in Java
for loop example in Java
Result Sets, Cursors and Transactions in SQL
JSP Tags for SQL to connect to a database
Using the qsort() and bsearch() functions with values - example program in C
Using qsort() and bsearch() with strings - example program in C
scanf and sscanf sample program in C
Use of {0} is required and Accessing resource bundles programmatically in Struts
Character Arrays in C
Pointers to functions in C++
atoi(), itoa() in C++
Ticker sample program in J2ME
DateFormat sample program in Java
Random class sample program in Java - nextGaussian(), nextBoolean(), nextBytes(), nextInt(), nextLong(), nextFloat(), nextDouble()
What Is a Reference in C++?

More Tutorials in Java
Update contents of a file within a jar file
Tomcat and httpd configured in port 8080 and 80
Java File
Java String
Count number of vowels, consonants and digits in a String in Java
Reverse a number in Java
Student marks calculation program in Java
Handling Fractions in Java
Calculate gross salary in Java
Calculate average sale of the week in Java
Vector in Java - Sample Program
MultiLevel Inheritance sample in Java
Multiple Inheritance sample in Java
Java program using Method Overriding
Java program to check if user input is an even number

More Latest News
Most Viewed Articles (in Java )
InetAddress Example program in Java
Read from a COM port using Java program
Stack example in Java - push(), pop(), empty(), search()
How to use ArrayList in Java
The Basic Structure of a Simple Java program
Using StringTokenizer in Java
FileReader and FileWriter example program in Java
Transient vs Volatile modifiers in Java
Vector example in Java
Method Overriding in Java
Method Overloading (function overloading) in Java
instanceof sample program in Java
append() in Java
Student marks calculation program in Java
Reading from a file and writing to a file using Java program
Most Emailed Articles (in Java)
Text to Speech conversion program in Java
inheritance in Java
How to initialize an Array and how to copy the array
Using Charts in JasperReports
What is Unicode?
Operator Precedence in Java
Of Object, equals (), == and hashCode ()
DateFormat sample program in Java
A Simple whois program in Java
PushbackReader sample program in Java
CharArrayReader example program in Java
ByteArrayOutputStream - sample program in Java
Vector example in Java
Arrays example in Java - asList(), binarySearch(), fill(), sort(), equals()
HashSet Sample program in Java