Java 5 features Enhanced for Loop | Varargs | Static import | Autoboxing and unboxing | Enum types | Generics | Annotations | By date |
Varargs allows you to avoid writing a method several times for multiple arguments. Before this feature, the solution was overloading methods. If the number of the arguments is unknown, you can use Varargs as shown in the exercise below. For more info click here to read Oracle’s explanation.
Note: By applying this feature to different types of arguments Varargs should be the last argument, see example 2.
Example 1: Varargs code
What is the output of the following code?
public class Varargs { // varargs arguments void write(String...names) { System.out.print("Robin"); for(String str: names) { System.out.print(str); } System.out.println(","); } public static void main(String[] args) { Varargs vg = new Varargs(); // no-argument demo vg.write(); // one-argument demo vg.write(" Emma"); // two-argument demo vg.write(" David", " Vera"); // four-argument demo vg.write(" Einstein", " Newton", " Darwin", " Tesla"); } }
Author: Sar Maroof
Answer explanation
By using Verargs invoking the methods with different arguments is possible.
Therefore, the program writes the following to the standard output.
Robin,
Robin Emma,
Robin David Emily Vera,
Robin Einstein Newton Darwin Tesla,
Example 2: Varargs as last argument
What is the output of the following code?
public class Varargs { // int and varargs arguments void write(int age, String...names) { for(String str: names) { System.out.print("Name: " + str); System.out.println(", Age: " + age); } } public static void main(String[] args) { Varargs vg = new Varargs(); // two-argument demo vg.write(23, "Emma"); // three-argument demo vg.write(31, "David", "Vera"); } }
Author: Sar Maroof
Answer explanation
This code write the following to the standard output.
Name: Emma, Age: 23
Name: David, Age: 31
Name: Vera, Age: 31
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