Methods

Methods

• A method is like a machine

• Zero or more inputs

• Zero or one output

• Other names:

  • Function

  • Procedure

Applications

• Scientists use mathematical functions to calculate formulas.

• Programmers use functions to build modular programs.

Example

Example

Example

Example

Example

Example

Example

Flow of control

(2)

(3)

flow of control

• What happens when a function is called:

1. Control transfers to the function code.

2. Argument variables are assigned the values given in the call.

3. Function code is executed.

4. Return value is assigned in place of the function

   name in calling code.

5. Control transfers back to the calling code. This is known as "pass by value”.

Scope

• Scope (of a variable):

  • The code that can refer to that variable.

Example

Memory management in stack

• What happens in memory when we call functions?

• What happens in memory when we define variables?

Don't forget static

Can't make static reference to method

returnType methodName(…) in class YourClass.

  static int min(int a, int b) {
    if (a < b)
      return a;
    else if (b < a)
      return b;
    System.out.println("they are equal!!!");
    return a;

  }

Control returns immediately from a method when a return is executed.

DUE SOOn

• Quiz Wednesday
• Lab 3 due Thursday at 10pm
• zybooks Chapter 7 due Friday at noon
• Program 2 (in zybooks - 3 parts) due Friday at 10pm