Calling a User-Defined Method

COMP 1010 Home > User-Defined_Methods

Introduction Now that you've written your first method, this section will show you how to use your method. Executing a method is known as calling the method. A method call consists of two methods: the method which performs the call, and the method which is called.

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Method Calling

Two methods are involved in every method call:

• The Called method is the method to execute.
• The Calling method or caller method is the method that requests execution of the called method.

To call a method:

1. Enter the name of the class containing the method if the called method is from a different class than the calling method.
2. Enter the name of the method followed by a left parenthesis (.
3. For each parameter in the called method, enter a variable or value of the same type as the parameter.
4. Close the method call using a right parenthesis ).

NOTE: If the called method has no parameters, you will still need to follow the method name with parentheses.

If the called method has a return value make sure to call the method in a place where the return value is used. Usually you will save the return value in a variable.

Example:

int sum;

// The sum of firstNum and secNum will be saved in the sum variable
sum = calculateSum(firstNum, secNum);
System.out.println(sum);

• If the called method and the calling method are in the same class, use the name of the method along with the parameters in parentheses.

Example:

methodName(firstNum, secNum);

• If the called method is in a different class than the calling method, write the name of the class before the method name, separated by a period, then the parameters following.

Example:

OtherClass.methodName(firstNum, secNum);

Consider the following code which you may be familiar with:

int firstValue = 10;
int secondValue = 14;
int maximum = Math.max(firstValue, secondValue);

In this statement you are telling Java to search the Math class for a method called max.

• To call a method which has no parameters, simply follow the method name with empty parentheses.

Example:

    methodName();

Method Calling Code Example

public class myClass 
{

	public static void main(String[] args)
	{
		int first = 23;
		int second = 68;
		int great;

		great = getGreaterInt(first, second); // Method call here
		System.out.println("Greater value of " + first + " and " + second + ": " + great);
	}
  
  
	public static int getGreaterInt( int value1, int value2 )
	{
		int biggest; //Declare a variable to hold the biggest int

		if ( value1 > value )
		{
			biggest = value1;
		}
		else
		{
			biggest = value2;
		}

		return biggest;
	}
 
}

Note the following line in the example above:

		great = getGreaterInt(first, second); // Method call here

This line contains a method call.

• The calling method, or caller method, is the main method.
• The called method is getGreaterInt.
• The method getGreaterInt accepts two int parameters.
  • In the method call two int values are passed to getGreaterInt. These values are known as arguments. Method arguments are explained in the next section.