How do I convert varargs to an array?

Varargs can be seen as a simplification of array when we need to pass a multiple value as a method parameter. Varargs it self is an array that automatically created, for these reason you will be enable to do things you can do with array to varargs.

In the example below you can see the messages parameter can be assigned to the String array variables, we can call the length method to the messages parameter as we do with the array. So actually you don’t need to convert varargs to array because varargs is array.

package org.kodejava.example.lang;

public class VarargsToArray {
    public static void main(String[] args) {
        printMessage("Hello ", "there", ", ", "how ", "are ", "you", "?");
    }

    public static void printMessage(String... messages) {
        String[] copiedMessage = messages;
        for (int i = 0; i < messages.length; i++) {
            System.out.print(copiedMessage[i]);
        }
    }
}

How do I create a method that accept varargs in Java?

Varargs (variable arguments) is a new feature in Java 1.5 which allows us to pass multiple values in a single variable name when calling a method. Of course it can be done easily using array but the varargs add another power to the language.

The varargs can be created by using three periods (...) after the parameter type. If a method accept others parameter than the varargs, the varargs parameter should be the last parameter to the method. And please be aware that overloading a varargs method can make harder to figure out which method is called in the code.

package org.kodejava.example.lang;

import java.util.Arrays;

public class VarArgsExample {
    public static void main(String[] args) {
        VarArgsExample e = new VarArgsExample();
        e.printParams(1, 2, 3);
        e.printParams(10, 20, 30, 40, 50);
        e.printParams(100, 200, 300, 400, 500);
    }

    public void printParams(int... numbers) {
        System.out.println(Arrays.toString(numbers));
    }
}

Running the code snippet give you the following output:

[1, 2, 3]
[10, 20, 30, 40, 50]
[100, 200, 300, 400, 500]