org.apache.derbyTesting.functionTests.util

Class UniqueRandomSequence

java.lang.Object

org.apache.derbyTesting.functionTests.util.UniqueRandomSequence

public class UniqueRandomSequence
extends java.lang.Object

Utility class that generates a sequence of unique numbers in random order. Example of how to use the generator to print all the numbers from 0 to 9 in random order:

 UniqueRandomSequence sequence = new UniqueRandomSequence(10);
 while (sequence.hasMore()) {
     System.out.println(sequence.nextValue());
 }
 

Field Summary

Fields

Modifier and Type	Field and Description
private int[]	numbers Array of the numbers to be used in the sequence.
private int	numbersLeft How many numbers are left in the sequence.
private java.util.Random	random Random number generator.

Constructor Summary

Constructors

Constructor and Description
UniqueRandomSequence(int length) Generate a random sequence with all the numbers from 0 up to length-1.
UniqueRandomSequence(int start, int length, int step) Generate a random sequence in the specified range.

Method Summary

Modifier and Type	Method and Description
boolean	hasMore() Check whether there are more numbers in the sequence.
int	nextValue() Fetch the next number from the sequence.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

numbers

private final int[] numbers

Array of the numbers to be used in the sequence.

random

private final java.util.Random random

Random number generator.

numbersLeft

private int numbersLeft

How many numbers are left in the sequence.

Constructor Detail

UniqueRandomSequence

public UniqueRandomSequence(int length)

Generate a random sequence with all the numbers from 0 up to length-1.

Parameters:

length - the length of the sequence

UniqueRandomSequence

public UniqueRandomSequence(int start,
                            int length,
                            int step)

Generate a random sequence in the specified range.

Parameters:

start - the smallest number in the sequence

length - the size of the sequence

step - the difference between adjacent numbers if the sequence is sorted

Method Detail

hasMore

public boolean hasMore()

Check whether there are more numbers in the sequence.

Returns:

true if there are more numbers in the sequence, false otherwise

nextValue

public int nextValue()

Fetch the next number from the sequence.

Returns:

a unique value in this generator's range