Variable Arguments (varargs) in Java

In Java, variable arguments (also called varargs) allow us to pass a variable number of arguments to a method. This feature simplifies method definitions by eliminating the need to define multiple overloaded methods for different argument counts.

Why Use Variable Arguments?#

• Allows a method to accept any number of arguments
• Eliminates the need for method overloading in some cases
• Increases code reusability and reduces redundancy

Syntax of varargs#

We use an ellipsis (...) after the data type to define a varargs method:

returnType methodName(dataType... variableName) { }

Example:

void displayNumbers(int... numbers) {
    // Method body
}

Example: Using Variable Arguments#

class VarargsExample {
  // Method with variable arguments
  static void printNumbers(int... numbers) {
    System.out.println("Number of arguments: " + numbers.length);

    // Loop through numbers and print each
    for (int num : numbers) {
      System.out.print(num + " ");
    }
    System.out.println();
  }

  public static void main(String[] args) {
    // Calling method with different number of arguments
    printNumbers(10, 20, 30);
    printNumbers(5, 15);
    printNumbers(100);
  }
}

Output:#

Number of arguments: 3
10 20 30
Number of arguments: 2
5 15
Number of arguments: 1
100

Explanation:

• The method printNumbers(int... numbers) can accept any number of integers.
• The numbers.length property helps in knowing the number of arguments passed.

Varargs with Other Parameters#

A varargs parameter must always be the last parameter in the method signature.

Example: Valid Varargs Usage#

class Example {
  static void showDetails(String name, int... marks) {
    System.out.println("Student: " + name);
    System.out.print("Marks: ");
    for (int mark : marks) {
      System.out.print(mark + " ");
    }
    System.out.println();
  }

  public static void main(String[] args) {
    showDetails("Alice", 85, 90, 95);
    showDetails("Bob", 80, 88);
  }
}

Output:#

Student: Alice
Marks: 85 90 95
Student: Bob
Marks: 80 88

Explanation:

• The name parameter is required, and varargs marks can take multiple values.
• Order matters: Regular parameters must come before varargs.

Limitations of Varargs#

❌ Cannot have multiple varargs in a method

void example(int... a, double... b) { } // ❌ Compilation error

❌ Must be the last parameter in the method

Conclusion#

In this blog, we learned how to pass Varargs to the method.

• Varargs allows a method to take a variable number of arguments.
• It eliminates overloading, making code more concise.
• It must be the last parameter in the method signature.