Lecture 15, CS 302-7 and 8, February 24

1. Reminders
1. Program 1

i. Due tonight

2. Review
1. Arrays

i. Array variables as pointers

2. For each loop
3. Methods
2. Methods
1. Think about our Java programs so far – we’ve put everything in this section called main

i. Public static void main(String[] args)

1. Underlined in this section J

2. Up until now – everything has been in the main method

i. Is this a method? Yes. But it’s kind of a special case. We’ll get to it later

3. What is a method? A method is a block of Java code that performs some task.
4. Why?

i. Modularity

1. Separate code that does different things

ii. Maintainability/readability

1. Think of different methods as black boxes – once they do what they are supposed to, don’t worry about them. Like using pseudocode, kind of

iii. Reduce redundancy

1. Don’t repeate code – advantages:

a. Less typing

b. If something doesn’t work, only need to fix it one place, instead of many

5. Examples that we’ve seen already:

i. Math.pow

ii. scanner.next

iii. random.nextInt

6. Methods have inputs and outputs:

i. Inputs – parameters

1. can be multiple

2. declare in method header

ii. Outputs – return values

1. only one

2. specify with return statement

3. declare in method header

iii. example - Math.pow(2,3) //2^3

4. So, how do you declare a method?

public static [return type] [name]([type1] param1,[type2] [param2] , …)

{

//body
}

1. Zero or one returns
2. We can have as many params as we want, including 0
3. Declare methods at Class level
4. MyRandom.java
4. Notes on Methods
1. Commenting: comment each method

i. Had some questions on this – when only one method, not a big deal

ii. But, when you have multiple methods, it is important

2. Parameters

i. Other names – argument

3. Variable scope – within block it is declared in
4. Watch outs –

i. Missing return values

5. Modifying parameters in body
5. HW
1. Read 5.3-5.5