java - 方法、字符串、字符有问题

Question

我目前正在尝试让我的代码在 hello world 中返回字母“d”，但我不确定代码有什么问题:

 public class StringTest{
    public static void main(String [] args){
        String test= "Hello World";
        world(test);
    }

    public static String world(String original){
        int x= original.charAt(original.length()-1);
        return x;
    }
}

Answer 1

在Java中，String.charAt(int index)返回一个字符，int不能隐式转换为char

您可以做的是将返回的字符转换为 String 中的 charAt:

public class StringTest{
    public static void main(String [] args){
        String test= "Hello World";
        world(test);
    }

    public static String world(String original)
    {
       return Character.toString(original.charAt(original.length()-1));
    }

Also, an even easier way:

Create empty String and conacatenate with your char. Automatically this converts char into String since we are adding an element to a String that in itself supports strings of these elements that are char:

    public static String world(String original)
    {
       return "" + original.charAt(original.length()-1); 
    }

}