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 Methods Defined by Random
| Method | Description | ||||
| boolean nextBoolean( ) | Returns the next boolean random number. | ||||
| void nextBytes(byte vals[ ]) | Fills vals with randomly generated values. | ||||
| double nextDouble( ) | Returns the next double random number. | ||||
| float nextFloat( ) | Returns the next float random number. | ||||
| double nextGaussian( ) | Returns the next Gaussian random number. | ||||
| int nextInt( ) | Returns the next int random number. | ||||
| int nextInt(int n) | Returns the next int random number within the range zero to n. | ||||
| long nextLong( ) | Returns the next long random number. | ||||
| void setSeed(long newSeed) | Sets the seed value (that is, the starting point for the random | ||||
| number generator) to that specified by newSeed. |
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();
}
}
}
Output
Average of values: 0.0702235271133344
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