Egge: New page: 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...

2008-03-05T02:35:49Z

New page: 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...

New page

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.

<geshi lang="java">
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;
}

}
</geshi>

[[Category:Java]]

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Egge: New page: 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...