1. What is an Array?
Why Arrays?
Programming Examples

2. Introduction/Review Array: A variable that can contain a list of data
All the same data type
Elements
Indexes/Subscripts
Array Length or Size
Question: What is the length of an array whose indexes go from 0 to 9?
11/16/2018
Wendi Jollymore, ACES

3. Why Use Arrays? See Psuedocode in the notes: Why Use Arrays? Click!
What does this code segment do?
What makes it inefficient?
How would it have to be modified
To process 6 courses?
To process 36 courses?
11/16/2018
Wendi Jollymore, ACES

4. Creating Arrays Arrays need to be declared double[] grades;
Data type, array name, square brackets
Arrays are objects!
11/16/2018
Wendi Jollymore, ACES

5. PROG 10082 - Object Oriented Programming 1
11/16/2018
Creating Arrays
You need to construct the array object
Then assign to the array variable
double[] grades = new double[4];
Primitive arrays’ elements are initialized.
Well learn about object arrays another time.
11/16/2018
Wendi Jollymore, ACES
Wendi Jollymore, ACES

6. PROG 10082 - Object Oriented Programming 1
11/16/2018
Arrays In Memory
The main array variable references the first element in the array object
11/16/2018
Wendi Jollymore, ACES
Wendi Jollymore, ACES

7. Accessing Arrays Refer to array elements by index/subscript:
// stores values in all the elements grades[0] = 89.2;
grades[1] = 75.0;
grades[2] = 69.8;
grades[3] = 85.5;
// prints the value in the 3rd element:
System.out.println(grades[2]);
11/16/2018
Wendi Jollymore, ACES

8. Exercises Do the written exercises in the notes
Try the programming exercises in the notes
11/16/2018
Wendi Jollymore, ACES

9. For-Each Loop Easy way to iterate through an array (section 6.2.7)
arrayDataType element
Declaration for a local variable that holds each element value during iteration
arrayVariable is the array you’re processing
for (arrayDataType element: arrayVariable) {
// refer to this element as "element" }
11/16/2018
Wendi Jollymore, ACES

10. For-Each Loop Example: This prints each array element on the screen
for (double g: grades) {
System.out.println(g); }
11/16/2018
Wendi Jollymore, ACES

11. Exercises Do the exercises in the notes
Try the programming exercises in the notes
11/16/2018
Wendi Jollymore, ACES