Groovy - Method Overloading

Method overloading refers to capability of Groovy to define multiple methods with same name but different parameters. Parameters may differ in either number of parameters, or types of parameters or order of parameters.

Example - Method Overloading

Following is an example demonstrating multiple add methods each having different arguments.

Example.groovy

class Calculator {
   void add(int a, int b) {
      println "$a + $b = " + (a + b)
   }

   void add(double a, double b) {
      println "$a + $b = " + (a + b)
   }

   void add(int a, int b, int c) {
      println "$a + $b + $c = " + (a + b + c)
   }
}

def calc = new Calculator()
calc.add(2, 3)
calc.add(2.5, 3.5)
calc.add(1, 2, 3)

Output

When we run the above program, we will get the following result.

2 + 3 = 5
2.5 + 3.5 = 6.0
1 + 2 + 3 = 6

Groovy determines call to corresponding add() method based on type of arguments or number of arguments passed.

Key Aspects of Method Overloading

• Static or Compile Time Polymorphism − Groovy decides call to corresponding overloaded method during compile time. It is also termed as a static polymorphism.

• Dynamic Resolution − Groovy is dynamic by nature. In case there is no exact match , Groovy picks up most specific type at runtime and calls the corresponding method.

• Default Parameters − With the use of default parameters, we can avoid method overloading in cases where number of arguments are varying.

• Ambiguity − In case, overloaded methods have related parameter types, for example, Number and Integer, then a value passed might match both the types, then it can lead to ambiguity at compile time. In such cases, Groovy resolves this by choosing the most specific type.

• Null Values − If multiple parameters can accept null values then passing null values to the overloaded methods can cause ambiguity. It is better to avoid such scenarios.

Example - Method Overloading Using Default Parameters

Following is an example demonstrating a single method greet called with different arguments.

Example.groovy

def greet(String name, String greeting = "Hi") {
   println "$greeting, $name!"
}

// prints Hi Alice!
greet("Alice")   
       
// prints Hello Bob
greet("Bob", "Hello")

Output

When we run the above program, we will get the following result.

Hi, Alice!
Hello, Bob!