Compare two version numbers version1 and version1.
If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.
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
The
For instance,
.
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 < 1.2.1 < 13.37This is a very simple question. The only problem with me is that I am not familiar with java.util.StringTokenizer.
import java.util.StringTokenizer; public class CompareVersionNumber { public int compareVersion(String version1, String version2) { if (version1 == null || version2 == null) return 0; StringTokenizer st1 = new StringTokenizer(version1, "."); StringTokenizer st2 = new StringTokenizer(version2, "."); while (st1.hasMoreTokens() && st2.hasMoreTokens()) { //must declare a new string, otherwise when comparing for the values, //it will through NoSuchElementException() if there exists only one token String s1 = st1.nextToken(); String s2 = st2.nextToken(); if (Integer.valueOf(s1) < Integer.valueOf(s2)) return -1; else if (Integer.valueOf(s1) > Integer.valueOf(s2)) return 1; } if (st1.hasMoreTokens() && !st1.nextToken().equals("0")) return 1; if (st2.hasMoreTokens() && !st2.nextToken().equals("0")) return -1; return 0; } }
Update: 2015 - 01 - 10
This time I use String.split, since "." is a special character, we need to add "\\." to escape that.
public int compareVersion(String version1, String version2) { if (version1 == null || version2 == null) throw new NullPointerException("Null Array!"); if (version1.equals(version2)) return 0; String[] v1 = version1.split("\\."); String[] v2 = version2.split("\\."); int l = v1.length >= v2.length ? v2.length : v1.length; for (int i = 0; i < l; i++) { if(Integer.parseInt(v1[i]) > Integer.parseInt(v2[i])) return 1; else if (Integer.parseInt(v1[i]) < Integer.parseInt(v2[i])) return -1; } if (l < v2.length) { for (int i = l; i < v2.length; i++) { if (Integer.parseInt(v2[i]) != 0) return -1; } } if (l < v1.length) { for (int i = l; i < v1.length; i++) { if (Integer.parseInt(v1[i]) != 0) return 1; } } return 0; }
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