What do parameters and return values have to do with methods?

Answer 1

Parameters and return values are a major part of methods. When defining a method, you must include information about the data types of the return value and the parameters. An example of a method definition is this:

public int getSumOfNumbers( int number1, int number2, int number3 )

{ return ( number1 + number2 + number3 ); }

The word "int" right after the word "public" is the return type. It describes what data type will be returned by the method. In this case, it was int, or integer.

The sequence of words in between the parantheses, "int number1, int number2, int number3", is the parameter list. Each of the phrases separated by a comma in the parameter list is a parameter. The first word - in this case "int" - is the data type of the parameter. It describes what type of variable the parameter will be. The second word - "number1", "number2", or "number3" - is the name of the parameter.

Every parameter must have a data type and a name, and every method must have a return type: even a method that returns nothing. For example:

public void evaluateNumber(int number)

{ if ( number > 0 )

{ System.out.println( number + " is positive." ); }

else if ( number < 0 )

{ System.out.println( number + " is negative." ); }

else

{ System.out.println( number + " is zero." ); }

}

When a method does not return data, its return type must be defined as void, as it is above.