Java Version

From EggeWiki

A frequent computer science problem is comparing version numbers. Version numbers are like decimal numbers with multiple decimal points. One can not accurately compare version numbers as a string or a number. Often you want to see if a version is later than another version. Here's a Java class which goes about solving this problem.

public class Version implements Comparable, Serializable {
	private final int version[];
 
	public Version(String version) {
		String[] split = version.split("\\.");
		this.version = new int[split.length];
		for (int i = 0; i < split.length; i++) {
			String string = split[i];
			this.version[i] = Integer.valueOf(string).intValue();
		}
	}
	private static final long serialVersionUID = 5028475470314950450L;
 
	public int compareTo(Object o) {
		if (this == o)
			return 0;
		final int[] other = ((Version) o).version;
		int length = Math.max(version.length, other.length);
		for(int i = 0; i < length; i++) {
			int x = (i < version.length) ? version[i] : 0;
			int y = (i < other.length) ? other[i] : 0;
			if (x < y)
				return -1;
			if (x > y)
				return 1;
		}
		return 0;
	}
 
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + Version.hashCode(version);
		return result;
	}
 
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		final Version other = (Version) obj;
		if (!Arrays.equals(version, other.version))
			return false;
		return true;
	}
 
	private static int hashCode(int[] array) {
		final int prime = 31;
		if (array == null)
			return 0;
		int result = 1;
		for (int index = 0; index < array.length; index++) {
			result = prime * result + array[index];
		}
		return result;
	}
 
	public String toString() {
		String s = "";
		for (int i = 0; i < version.length; i++) {
			if (!"".equals(s))
				s += ".";
			s += Integer.toString(version[i]);
		}
		return s;
	}
 
}