Java Version Compare versionCompare(String str1, String str2)

Description

Compares two version strings.

License

Open Source License

Parameter

Parameter	Description
str1	a string of ordinal numbers separated by decimal points.
str2	a string of ordinal numbers separated by decimal points.

Return

The result is a negative integer if str1 is _numerically_ less than str2. The result is a positive integer if str1 is _numerically_ greater than str2. The result is zero if the strings are _numerically_ equal.

Declaration

public static int versionCompare(String str1, String str2)

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    /**/* ww w .  ja  v  a 2s .  c  o  m*/
     * Compares two version strings.
     * 
     * Use this instead of String.compareTo() for a non-lexicographical
     * comparison that works for version strings. e.g. "1.10".compareTo("1.6").
     * 
     * @note It does not work if "1.10" is supposed to be equal to "1.10.0".
     * 
     * @param str1
     *            a string of ordinal numbers separated by decimal points.
     * @param str2
     *            a string of ordinal numbers separated by decimal points.
     * @return The result is a negative integer if str1 is _numerically_ less
     *         than str2. The result is a positive integer if str1 is
     *         _numerically_ greater than str2. The result is zero if the
     *         strings are _numerically_ equal.
     */
    public static int versionCompare(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) {
            String v = vals1[i];
            int index = v.indexOf('-');
            if (index > -1) {
                // ex : 1-insiders
                v = v.substring(0, index);
            }
            int diff = Integer.valueOf(v).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"
        return Integer.signum(vals1.length - vals2.length);
    }
}