java - Transforming int to char with input (edited) -

my program should transform letter letter 2 letter away it. c, b d. , can use first 10 letters in english alphabet. ('i' go 'a' , 'j' go 'b' cuz can use 10 letters.

 import java.util.scanner;     public class part6 {     public static void main(string[] args) {     scanner keyboard=new scanner(system.in);      system.out.println("please enter 4 letter word uses first 10 letter on english alphabet(a,b,c,d,e,f,g,h,i,j):  ");      scanner keyboard=new scanner(system.in);     string s1 = keyboard.next();     string s2 = "z1";     s2=s1.tolowercase();  if (s1.length() !=4) system.out.println("please enter word 4 letters");  char c1= s2.charat(0); char c2= s2.charat(1); char c3= s2.charat(2); char c4= s2.charat(3);  int i1 =(int) c1; int i2= (int) c2; int i3= (int) c3; int i4= (int) c4;  if(i1>96 && i1<107) // = 97 , j = 106 system.out.println(s2); else if (i2>96 && i2<107) system.out.println(s2); else if (i3>96 && i3<107) system.out.println(s2); else if (i4>96 && i4<107) system.out.println(s2); else  system.out.println("wrong character using!"); } } 

so new problem uhm if enter abcy or aaaq , abcy , aaaq. int not work. should ?

    public static char transform(char s){         int base = s - 'a';         int increment = base + 2;         int circularshiftincrement = increment % 10;         int transformtocharvalue = circularshiftincrement + 'a';          return (char)transformtocharvalue;     }      public static void main(string[] args) {         scanner scanner = new scanner(system.in);         while(scanner.hasnext()){             string s = scanner.next();             char c = s.charat(0);             char transformedstring = transform(c);             system.out.println(transformedstring);         }     }