1. Announcements & Review
Last Time: arrays of objects
Items[] apples;
appleTypes = 8;
apples = new Items[appleTypes];
apples[0] = new Items(”Granny Smith", 22);
Announcements
Exam:
2/28 5:30-7:30pm
GEO 2.216
Brief study guide on web (see detailed schedule)
Lecture 16: Visualizing and Using Arrays

2. Initializing Array of Objects
Items[] apples = new Items[3];
apples ->
null 1 2
null
null
Lecture 16: Visualizing and Using Arrays

3. Initializing Array of Objects
Items[] apples = new Items[3];
apples[2] = new Items(“Granny Smith”, 22);
apples -> G r a n y S m i t h 1 2
name
22 (amount)
null
null
Lecture 16: Visualizing and Using Arrays

4. Initializing Array of Objects
Items[] apples = new Items[3];
apples[2] = new Items(“Granny Smith”, 22);
apples[0] = apples[2];
apples -> G r a n y S m i t h 1 2
name
22 (amount)
null
Lecture 16: Visualizing and Using Arrays

5. Visualizing an Array of Objects
...
apple[0].setName("McIntosh”);
apple[1].setAmount(10);
apples -> G r a n y S m i t h 1 2
name
22 (amount)
name
10 (amount)
name
30 (amount) G o l d e n D i c u s M c I n t o s h
Lecture 16: Visualizing and Using Arrays

6. Lecture 16: Visualizing and Using Arrays
Swapping Elements
// let’s swap apple[0] and apple[2]
Items tmp = apple[0]; // Make a temporary copy. Why?
apples -> G r a n y S m i t h 1 2
name
22 (amount)
name
10 (amount)
tmp
name
30 (amount) G o l d e n D i c u s M c I n t o s h
Lecture 16: Visualizing and Using Arrays

7. Lecture 16: Visualizing and Using Arrays
Swapping Elements
// let’s swap apple[0] and apple[2]
Items tmp = apple[0]; // Make a temporary copy. Why?
apple[0] = apple[2];
apples -> G r a n y S m i t h 1 2
name
22 (amount)
name
10 (amount)
tmp
name
30 (amount) G o l d e n D i c u s M c I n t o s h
Lecture 16: Visualizing and Using Arrays

8. Lecture 16: Visualizing and Using Arrays
Swapping Elements
// let’s swap apple[0] and apple[2]
Items tmp = apple[0]; // Make a temporary copy. Why?
apple[0] = apple[2];
apple[2] = tmp
apples -> G r a n y S m i t h 1 2
name
22 (amount)
name
10 (amount)
tmp
name
30 (amount) G o l d e n D i c u s M c I n t o s h
Lecture 16: Visualizing and Using Arrays

9. Lecture 16: Visualizing and Using Arrays
Swapping Integers
// swap a & b
public void swap(int a, int b) {
int t = a;
a = b;
b = t; }
int a = 10;
int b = 20;
swap (a, b); // a = 20; b = 10;
Lecture 16: Visualizing and Using Arrays

10. Lecture 16: Visualizing and Using Arrays
BlueJ Examples
Problems
Extend Inventory class for tracking Items
Lecture 16: Visualizing and Using Arrays

11. Lecture 16: Visualizing and Using Arrays
More Questions?
Lecture 16: Visualizing and Using Arrays