难点：

1、判断每个字符是否大小写

2、小写字符位置+1

import java.util.*;

public class Main{ public static void main(String[] args){ Scanner in = new Scanner(System.in); StringBuilder builder = new StringBuilder(in.nextLine()); System.out.println(strHandle(builder)); }

public static StringBuilder strHandle(StringBuilder builder){
    int len = builder.length();
    for(int i = 0; i < len ;i++){
        char c = builder.charAt(i);
        String cstr = builder.charAt(i)+"";
        if(Character.isLowerCase(c)){
            
            if("abc".indexOf(cstr) >= 0){
                builder.setCharAt(i,'2');
            }else if ("def".indexOf(cstr) >= 0){
                builder.setCharAt(i,'3');
            }else if ("ghi".indexOf(cstr) >= 0){
                builder.setCharAt(i,'4');
            }else if ("jkl".indexOf(cstr) >= 0){
                builder.setCharAt(i,'5');
            }else if ("mno".indexOf(cstr) >= 0){
                builder.setCharAt(i,'6');
            }else if ("pqrs".indexOf(cstr) >= 0){
                builder.setCharAt(i,'7');
            }else if ("tuv".indexOf(cstr) >= 0){
                builder.setCharAt(i,'8');
            }else{
                builder.setCharAt(i,'9');
            }
        }else if (Character.isUpperCase(c)){
            
            if(!"Z".equals(cstr)){
                builder.setCharAt(i,(char)(c+'a'-'A'+1));
            }else{
                builder.setCharAt(i,'a');
            }
        }
    }
    return builder;
}

}