Lecture for March 13th

Methods

Methods are small blocks of statements that make it easier to solve a problem. It usually focuses on solving a small part of the overall problem.

Usually in methods you provide some sort of input and get some output out of it.

Advantages

• Code readability
• Modular program development (break up the problem in chunks)
• Incremental development
• No redundant code!

Method definition

Consists of a method name, input and output and the block of statements.

Usually this is succinctly written using JavaDocs which is what you see in the JavaAPI

Method Call

A method call is the execution of the method. The statements defined in the method is what will execute.

Method Stubs

Recall from method definition the parts of the method definition. Now look at the following method

String[] split(String s)

The output here is String[]

The method name is split

The input is String s

Modular Programming

Let us look at the following example:

The program should have a list of grocery prices. It should be able to calculate the total cost of groceries. The store gives a student discount of 5%. The program should calculate this discount and update the total, it should calculate and add the 2.5% tax.

• First you should add it all up
• Then compute the discount
• Then add the tax

Parts of a method definition

public static int timesTwo(int num) {
    int two = num * 2;
    return two;
}

It first starts off by declaring the visibility public

The return type if int

The method name is timesTwo

The input parameter is int num

Between the curly braces is the body of the method

Calling a Method

int a = 5;
int b = 3;

int ans = multiply(a, b)

The method call is multiply(a, b) and the result is stored in the variable ans