[Java]努力按字母顺序排列字符串

Question

I am trying to create a void method that uses 3 string parameters and puts the strings in alphabetical order. So far I have used if statements and I believe the if statements are correct however I keep getting a message that says "void cannot be converted into string" I am suppose to use a void method and I am very confused this is my code

public class AlphabeticalOrder {

    public static void inOrder(String s1, String s2, String s3) {
        if (s1.compareTo(s2) < 0 && s1.compareTo(s3) < 0)
            if (s2.compareTo(s3) < 0)
                System.out.println(s1 + s2 + s3);
            else
                System.out.println(s1 + s2 + s3);
        else if (s2.compareTo(s1) < 0 && s2.compareTo(s3) < 0)
            if (s1.compareTo(s3) < 0)
                System.out.println(s2 + s1 + s3);
            else
                System.out.println(s2 + s3 + s1);
        else if (s3.compareTo(s1) < 0 && s3.compareTo(s2) < 0)
            if (s2.compareTo(s1) < 0)
                System.out.println(s3 + s2 + s1);
            else
                System.out.println(s3 + s1 + s2);
    }

    public static void main(String[] args) {
        String ans1 = inOrder("abc", "mno", "xyz");
        System.out.println(ans1);
    }
}

Answer 1

Change your main method to this:

public static void main(String[] args)
{
    inOrder("abc", "mno", "xyz");
}

Your function returns "void", which means "nothing", so you can't assign it to a variable or print it.

The better way to do this is almost certainly to have your method return a String[] , but if your assignment is to return void , then this is the best you've got.

Answer 2

in addition to JoshuaD answer, I propose you use more convenient way to sort this using Stream API .

private static void inOrder(String s1, String s2, String s3) {
    Stream.of(s1, s2, s3).sorted().forEach(System.out::println);
}