import java.io.IOException;
import java.io.InputStreamReader;
public class ChangeLetter {
public static void main(String[] args) {
String outputStr = "";
System.out.print("請輸入字母：");
//從鍵盤輸入字母
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
try {
//讀取行，賦值給inputStr
String inputStr = br.readLine();
for(int i=0;i<inputStr.length();i++){
//將轉換後的字符連接成字符串輸出
outputStr = outputStr + changeLetter(inputStr.charAt(i));
}
} catch (IOException e) {
e.printStackTrace();
}
System.out.println(outputStr);
}
public static char changeLetter(char c){
//用於後臺打印，知道Unicode碼
/*Integer num1 = 'A';
Integer num2 = 'Z';
Integer num3 = 'a';
Integer num4 = 'z';
System.out.println(num1);
System.out.println(num2);
System.out.println(num3);
System.out.println(num4);*/
//unicode碼
//A值為65
//Z值為90
//a值為97
//b值為122
int letter = c;
char character = 0;
if(c>=65&&c<=90){
//比如輸入B，則運算步驟如下：
//90-（66-65）=89，89轉換成字符則為Y
//以下小寫的同理
character = (char)(90-(letter-65));
}
if(c>=97&&c<=122){
character = (char)(122-(letter-97));
}
return character;
}
}
運行結果：
請輸入字母：ABCXYZabcxyz
ZYXCBAzyxcba