java - 检查第一个字符是否等于最后一个字符

Question

我是 java 的新手，我想知道如果第一个字母和最后一个字母不相同，如何将我的代码返回 false

他的整个指令是定义和测试一个名为 checkString 的方法，该方法将单词作为参数并检查字符串是否以相同的字母开头和结尾。如果两个字母相同，则该方法返回 true，否则返回 false(返回 boolean 值)。该程序将小写字母和大写字母视为等同

这是我所拥有的:

    import java.util.Scanner;
    public class Excercise5 {
        public static void main(String[] arg) {
            Scanner keyboard = new Scanner(System.in);
            System.out.print("Type a string: ");
            String word = keyboard.nextLine(); 
            System.out.printf ("%s begins and ends with the same letter.", checkString(word));
        }
        public static boolean checkString (String word) {   
            int stringLength = word.length();
            String letter1 = (word.substring (0,1)).toUpperCase();
            String lastletter = (word.substring ((stringLength-1),(stringLength))).toUpperCase();

            if (letter1.equals(lastletter)){
                return true;
            } else {
                return false;
            }
        }
    }

Answer 1

根据您的代码；而不是:

if (letter1.equals(lastletter)) {
  return true;
} else {
  return false;
}

只是做:

return letter1.equals(lastletter);

但是您的 checkString() {...} 代码应该是:

public static boolean checkString (String word) {
  int len = word.length();
  word = word.toUpperCase(); //since you are testing them as upper case
  char firstLetter = word.charAt(0);
  char lastLetter = word.charAt(len - 1);
  return firstLetter == lastLetter;
}

也代替:

System.out.printf (word + " begins and ends with the same letter.", checkString(word));

使用print():

System.out.print(word + " begins and ends with the same letter: " + checkString(word));

编辑:

如果你想使用 printf() 试试像这样:

System.out.printf("%s begins and ends with the same letter. %s", word , checkString(word));

%s 就像是 word 的占位符和 checkString(word) 返回的值。