VersionComparator.java

package com.ladjzero.uzlee.utils;

import java.util.Comparator;

/**
 * Created by chenzhuo on 16-3-14.
 */
public class VersionComparator implements Comparator<String> {
	@Override
	public int compare(String str1, String str2) {
		String[] vals1 = str1.split("\\.");
		String[] vals2 = str2.split("\\.");
		int i = 0;
		// set index to first non-equal ordinal or length of shortest version string
		while (i < vals1.length && i < vals2.length && vals1[i].equals(vals2[i])) {
			i++;
		}
		// compare first non-equal ordinal number
		if (i < vals1.length && i < vals2.length) {
			int diff = Integer.valueOf(vals1[i]).compareTo(Integer.valueOf(vals2[i]));
			return Integer.signum(diff);
		}
		// the strings are equal or one string is a substring of the other
		// e.g. "1.2.3" = "1.2.3" or "1.2.3" < "1.2.3.4"
		else {
			return Integer.signum(vals1.length - vals2.length);
		}
	}
}