Compare Version Numbers

Compare two version numbers version1 and version2.
If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.
The . character does not represent a decimal point and is used to separate number sequences.
For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37

public int compareVersion(String version1, String version2) {        String[] levels1 = version1.split("\\.");        String[] levels2 = version2.split("\\.");            int length = Math.max(levels1.length, levels2.length);        for (int i=0; i<length; i++) {        //三目运算符针对1.0.1&1.4这种情况            Integer v1 = i < levels1.length ? Integer.parseInt(levels1[i]) : 0;            Integer v2 = i < levels2.length ? Integer.parseInt(levels2[i]) : 0;            int compare = v1.compareTo(v2);            if (compare != 0) {                return compare;            }        }        return 0;    }