"char cannot be dereferenced error"

[Robbie Harjes]

I'm trying to make a simple, 1-to-1 character conversion "Encryption" program. Here is the code:

public class mono {
  public static void main (String args[]) {
char[][] ct= { {'a','b'},
       {'b','c'},
       {'c','d'},
       {'d','e'},
       {'e','f'},
       {'f','g'},
       {'g','h'},
       {'h','i'},
       {'i','j'},
       {'j','k'},
       {'k','l'},
       {'l','m'},
       {'m','n'},
       {'n','o'},
       {'o','p'},
       {'p','q'},
       {'q','r'},
       {'r','s'},
       {'s','t'},
       {'t','u'},
       {'u','v'},
       {'v','w'},
       {'w','x'},
       {'x','y'},
       {'y','z'},
       {'z','a'},
     };
//ct[2][25] not ct[25][2]

System.out.println("Type in a sentence to be encrypted.");
String a= TextIO.getln();
String b=""; 

for (int x= 0; x < a.length(); x++) {
for (int i= 0; i< 26; i++) {
char TEMP=a.charAt(i);
if (TEMP.compareTo((ct[1][i])==0)) {
  TEMP=TEMP.replace((ct[1][i]), (ct[2][i]));
  b= b + TEMP;
               }
}
}

System.out.println(b);

  } //end main
}  //end class mono

(The program is not finished...Just what I have)
I know it has to do with the array referencing... I read somewhere to try putting it in an extra set of parathesee's, but that didn't work.. Sorry if this paintstakingly obvious... I can't figure it out.
[ November 09, 2003: Message edited by: Robbie Harjes ]

[William Barnes]

You didn't mention what your exact problem is. Does it not compile? What is the error?
I think you have an extra comma after last set - mapping z to a.
And this

if (TEMP.compareTo((ct[1][i])==0)) 

I think you are doing the "==" at the wrong level. You want to compare the result of the "compareTo" to zero. At the moment you are comparing the character at [1][i] to zero.

[Robbie Harjes]

The exact problem is this: It won't compile. When I try to compile it, I get the "char cannot be dereferenced" error, and it points to the periods:
if (TEMP.compareTo((ct[1][i])==0)) {
^
*and*
TEMP=TEMP.replace((ct[1][i]), (ct[2][i]));
^
William Barnes... I believe you have it right... But how would I fix that? create a new char (ex. char NEW=ct[1][i] so that I am comparing the character and not the reference to the array?

[Robbie Harjes]

Sorry about the double posting here...
Your right on that it should be: if (TEMP.compareTo((ct[1][i]))==0)
but I still get the errors:
<pre>
C:\java>javac mono.java
mono.java:46: char cannot be dereferenced
if (TEMP.compareTo((ct[1][i]))==0) {
^
mono.java:47: char cannot be dereferenced
TEMP=TEMP.replace((ct[1][i]), (ct[2][i]));
^
2 errors
</pre>

[William Barnes]

Now you have too many parens in the "compareTo". You are saying "compareTo((something))". One layer too many parens.

[William Barnes]

Looking at the API I see that you are using "compareTo" method incorrectly. The signiture is "int compareTo( Character, anotherCharator)". So your "TEMP" should be the first parameter in this call. Make sense?

[William Barnes]

And I don't find "replace". Maybe you are thinking of the String class?

[William Barnes]

Ignore may answers, Jeanne Boyarsky on the other thread has it. "char" is a primative - isn't a class and doesn't have access to all those nice methods.
You can use the "Character" class instead of "char" if you want those methods.