Java: How to do increment in letter

Question

I will be reading in a String of two character in Java. And I want to determine what will be the next increment of it. Below is the rules of increment.

AA -> AB -> AC -> ... -> AZ -> BA -> BB -> ... -> ZZ -> AA

So if I read in AC, I will print out AD.

EDIT

I can do increment of one character, like this System.out.println((char) ('C' + 1));. So I was thinking about parsing the string, get the individual character, just increment or decrement the value of char. The wrap around is what get me, like AZ -> BA. Not sure what the best way to achieve that yet. What are your thought

@Oil: I can do increment of one character, like this `System.out.println((char) ('C' + 1));`. So I was thinking about parsing the string, get the individual character, just increment or decrement the value of `char`. The wrap around is what get me, like `AZ` -> `BA`. Not sure what the best way to achieve that yet. What are your thought — Thang Pham, May 19 '11 at 14:56
This question has been already answered here: http://stackoverflow.com/questions/342052/how-to-increment-a-java-string-through-all-the-possibilities — Miquel, May 19 '11 at 14:54

score 5 · Accepted Answer · answered May 19 '11 at 15:31

5

public static String increment(final String p_source) {
    final int first = (p_source.charAt(0) - 'A') * 26;
    final int second = p_source.charAt(1) - 'A';

    final int next = (first + second + 1) % (26*26); 

    return new String(new byte[] {(byte)(next / 26 + 'A'), (byte)(next % 26 + 'A')});
}

answered May 19 '11 at 15:31

Martin Gamulin

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Told you it wasn't that complex :) – Yochai Timmer May 19 '11 at 16:11
1

@Yochai: I know, that why I comment on your post and said that I like this base 26 counting. Thank you :D – Thang Pham May 19 '11 at 16:24

score 1 · Answer 2 · answered May 19 '11 at 14:54

1

if its 2 letter stuff then

public static String getString(String str){
  String str1 = str;
   str = str.ToLower(); 
  char c1 = str.charAt(0);
  char c2 = str.charAt(1);
  if(c2<Z){
     c2 = c2+1;
  }else{
     c2= 'A';
     if(c1 < z){
      c1 = c1+1;
     }else{
       //you put this thing
     }
  }
     //      return a string concating char
}

Note: just a demonstration , to give you basic idea

answered May 19 '11 at 14:54

jmj

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you can compare `char` with a `<` sign like that? And is there a reason that you convert the String to lower case? – Thang Pham May 19 '11 at 15:05
@HarryPham yes, and reason is to ignore conflict between `A`,`a` as they have different ascii – jmj May 19 '11 at 15:46

score 1 · Answer 3 · answered May 19 '11 at 14:55

You could take the second char from each pair and convert it to ascii, then bump the ascii by one and concatenate it back to the first char. This site shows you how to convert a char to ascii in Java: http://www.roseindia.net/java/java-conversion/CharToASCIIi.shtml

Yochai Timmer · Answer 4 · 2011-05-19T15:03:18.470

1

you have 26 letters... so you have a range of 26*26

Parse it to an int, then calculate mod(26*26)

AA = 0*26^0+0*26^1 = 0

BA = 0*26^0+1*26^1 = 26

etc...

Then you can play that number and parse it with those rules

edited May 19 '11 at 15:03

answered May 19 '11 at 14:56

Yochai Timmer

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It's supposed to be 26^1 ... fixed it – Yochai Timmer May 19 '11 at 15:03
So let say I read in `AC`, so after the parse I got `2`. So the next increment is `3`. Then I guess here I have to somehow associate `3` with `AD`, aint I? It is a bit complex in my opinion. Dont you think so? – Thang Pham May 19 '11 at 15:10
No, it's not complex, simpler than a ToHex() function, the target characters are in the same range. – Yochai Timmer May 19 '11 at 15:15
I see. I actually like this base 26 counting technique. Thank you very much. – Thang Pham May 19 '11 at 16:10

Java: How to do increment in letter

4 Answers4