Simple question

Question

What is the output of this code?

public class Program {
public static void main(String[] args) {
String a = “one”, b = “two”;
String c = String.join(a, b);
System.out.print(c);
}
}

Answer: two - please explain me

Answer 1

The join method takes at first a char sequence delimeter and then another char sequence for the elements

String.join("/", "a","b","c") would be: "a/b/c"

String.join("+", "1","2","3","4") would be "1+2+3+4"

In your case: a is the delimeter and b the element. One element don't need an delimeter, so the output is just "two". You can see what happens if you add another String.
String c = String.join(a,b,"three");

For more details you can read this article: https://www.javapoint.com/java-string-join

Answer 2

In this case you are passing two strings to the join() method, so the following method signature is invoked:
public static String join(CharSequence delimiter, CharSequence... elements)
a is the delimiter
b is the first element
But because there are no more elements to combine, the delimiter is not used. That's why the result is two.

https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#join-java.lang.CharSequence-java.lang.CharSequence...-

Answer 3

For join method, the first argument is delimiter..., next arguments are string to be joined..
For ex:
S=String.join("@", "abc", "cdf"," ef");
Now S=abc@cdf@ef;
Delimiter is added in between string not at end, not at start so,
Since in your example, have only one string, one delimiter, output is two..