Efficient way to compare version strings in Java [duplicate]

Question

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How do you compare two version Strings in Java?

I've 2 strings which contains version information as shown below:

str1 = "1.2" str2 = "1.1.2" 

Now, can any one tell me the efficient way to compare these versions inside strings in Java & return 0 , if they're equal, -1, if str1 < str2 & 1 if str1>str2.

Answer 1

Requires commons-lang3-3.8.1.jar for string operations.

/**  * 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").  *   * @param v1 a string of alpha numerals separated by decimal points.   * @param v2 a string of alpha numerals separated by decimal points.  * @return The result is 1 if v1 is greater than v2.   *         The result is 2 if v2 is greater than v1.   *         The result is -1 if the version format is unrecognized.   *         The result is zero if the strings are equal.  */  public int VersionCompare(String v1,String v2) {     int v1Len=StringUtils.countMatches(v1,".");     int v2Len=StringUtils.countMatches(v2,".");      if(v1Len!=v2Len)     {         int count=Math.abs(v1Len-v2Len);         if(v1Len>v2Len)             for(int i=1;i<=count;i++)                 v2+=".0";         else             for(int i=1;i<=count;i++)                 v1+=".0";     }      if(v1.equals(v2))         return 0;      String[] v1Str=StringUtils.split(v1, ".");     String[] v2Str=StringUtils.split(v2, ".");     for(int i=0;i<v1Str.length;i++)     {         String str1="",str2="";         for (char c : v1Str[i].toCharArray()) {             if(Character.isLetter(c))             {                 int u=c-'a'+1;                 if(u<10)                     str1+=String.valueOf("0"+u);                 else                     str1+=String.valueOf(u);             }             else                 str1+=String.valueOf(c);         }                     for (char c : v2Str[i].toCharArray()) {             if(Character.isLetter(c))             {                 int u=c-'a'+1;                 if(u<10)                     str2+=String.valueOf("0"+u);                 else                     str2+=String.valueOf(u);             }             else                 str2+=String.valueOf(c);         }         v1Str[i]="1"+str1;         v2Str[i]="1"+str2;              int num1=Integer.parseInt(v1Str[i]);             int num2=Integer.parseInt(v2Str[i]);              if(num1!=num2)             {                 if(num1>num2)                     return 1;                 else                     return 2;             }     }     return -1; }