多分支if else語句

Question

我試圖將單個字符識別爲大寫或小寫字母。我遇到了if else語句的邏輯問題。任何幫助將非常感激。當它運行時，現在將打印它是大寫還是小寫。

String x = ""; 

if (Character.isLetter(x)) { 
     System.out.println(x + " is a letter."); 
    } 
    else if (Character.isUpperCase(x)) { 
     System.out.println(x + " is upper case."); 
    } 
    else if (Character.isLowerCase(x)) { 
     System.out.println(x + " is lower case."); 
    } 

Answer 1

嘗試......

if (Character.isLetter(x)) { 
    System.out.println(x + " is a letter."); 
    if (Character.isUpperCase(x)) { 
     System.out.println(x + " is upper case."); 
    } 
    else if (Character.isLowerCase(x)) { 
     System.out.println(x + " is lower case."); 
    } 
}