Java输入一个字母，输出其前后的字母

import java.util.*;
class Test{
 public static void main(String[] args)
 {
  Scanner x=new Scanner(System.in);
  char a=x.nextchar();
if(a>='a'&&a<'z')
    System.out.print(a-1);
    System.out.print(a);
    System.out.print(a+1);
 else if(a=='z')
    System.out.print(a-1);
    System.out.print(a);
    System.out.print("a");

 if(a>='A'&&a<'Z')
    System.out.print(a-1);
    System.out.print(a);
    System.out.print(a+1);
 else if(a=='Z')
    System.out.print(a-1);
    System.out.print(a);
    System.out.print("A");
 else
     System.out.println("输入不正确");
 }
 }