Calling a User-Defined Method
COMP 1010 Home > User-Defined_Methods
IntroductionNow 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:
- Enter the name of the method followed by a left parenthesis (.
- For each parameter in the called method, enter a variable or value of the same type as the parameter.
- 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.
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.