String.join() method

Since JDK 1.8

String java.lang.String.join(CharSequence delimiter, CharSequence... elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

For example,

String message = String.join(delimiter, element-1, elements-2, ….);

     // message returned is: "Java-is-cool"

Note that if an element is null, then "null" is added.

Returns a new String that is composed of the elements separated by the delimiter

Throws NullPointerException, If delimiter or elements is null.

String java.lang.String.join(CharSequence delimiter, Iterable<? extends CharSequence> elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

Iterable that will have its elements joined together.

package core.string;

import java.util.ArrayList;

import java.util.List;

public class StringJoinExample {

       public static void main(String[] args) {

              String message = String.join("-", "Java", "is", "cool");

              System.out.println(message);

              String messageNull = String.join("-", "Java", null, "cool");

              System.out.println(messageNull);

              List<String> list = new ArrayList<String>();

              list.add("Java");

              list.add("is");

              list.add("cool");

              String messageIter = String.join(" : ",list );

              System.out.println(messageIter);

       }

}

Output:

Java-is-cool

Java-null-cool

Java : is : cool