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hablutzel1/JavaVersionComparator.java

Created May 31, 2015 15:39
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Basic Comparator to compare/order Java versions, e.g. 1.7.0_79 vs 1.8.0_45
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JavaVersionComparator.java
package com.company;
import java.util.Comparator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Very basic comparator
* <p><b>Warning: it could be unstable because there are more possible patterns for Java versions
*/
public class JavaVersionComparator implements Comparator<String> {
@Override
public int compare(String firstVersion, String secondVersion) {
// TODO check http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html for improved robustness
Pattern basicJavaVersionRegex = Pattern.compile("(\\d+)\\.(\\d+)\\.(\\d+)_(\\d+)");
Matcher firstMatcher = basicJavaVersionRegex.matcher(firstVersion);
firstMatcher.find();
Integer firstN1 = Integer.valueOf(firstMatcher.group(1));
Integer firstN2 = Integer.valueOf(firstMatcher.group(2));
Integer firstN3 = Integer.valueOf(firstMatcher.group(3));
Integer firstN4 = Integer.valueOf(firstMatcher.group(4));
Matcher matcher2 = basicJavaVersionRegex.matcher(secondVersion);
matcher2.find();
Integer secondN1 = Integer.valueOf(matcher2.group(1));
Integer secondN2 = Integer.valueOf(matcher2.group(2));
Integer secondN3 = Integer.valueOf(matcher2.group(3));
Integer secondN4 = Integer.valueOf(matcher2.group(4));
int result = firstN1.compareTo(secondN1);
if (result != 0) return result;
result = firstN2.compareTo(secondN2);
if (result != 0) return result;
result = firstN3.compareTo(secondN3);
if (result != 0) return result;
return firstN4.compareTo(secondN4);
}
}
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