// Copyright (c) 2003-2009, Jodd Team (jodd.org). All Rights Reserved.
/**
* Simple synchronized int ids sequence generator. It takes the positive sequence range (boundaries are included).
* Optionally, it supports cycling, when counter reaches the max value. Otherwise an exception is thrown.
* @see SimpleLongIdGenerator
*/
public class SimpleIdGenerator {
protected volatile int value;
protected int initialValue;
protected int maxValue;
protected boolean cycle;
/**
* Creates a new default cycled id generator. Starts from 1 and counts up to max int value.
*/
public SimpleIdGenerator() {
this(1, Integer.MAX_VALUE, true);
}
/**
* Creates a new cycled id generator with specified initial value.
*/
public SimpleIdGenerator(int initialValue) {
this(initialValue, Integer.MAX_VALUE, true);
}
/**
* Creates a new cycled id generator with specified range.
*/
public SimpleIdGenerator(int initialValue, int maxValue) {
this(initialValue, maxValue, true);
}
/**
* Creates a new id generator with specified range and cycling flag.
*/
public SimpleIdGenerator(int initialValue, int maxValue, boolean cycle) {
if (initialValue < 0) {
throw new IllegalArgumentException("Initial value '" + initialValue + "' must be a positive number.");
}
if (maxValue <= initialValue) {
throw new IllegalArgumentException("Max value '" + maxValue + "' is less or equals to initial value '" + initialValue + "'.");
}
this.initialValue = this.value = initialValue;
this.maxValue = maxValue;
this.cycle = cycle;
}
/**
* Returns the next value from the sequence. Thread-safe.
*/
public synchronized int next() {
int id = value;
value++;
if ((value > maxValue) || (value < 0)) {
if (cycle == false) {
throw new IllegalStateException("Max value already reached.");
}
value = initialValue;
}
return id;
}
}