Lecture 16: Visualizing and Using Arrays

Announcements & Review

Announcements

Exam: 2/28 5:30-7:30pmGEO 2.216

Brief study guide on web (see detailed schedule)

Last Time: arrays of objects

Items[] apples;

appleTypes = 8; apples = new Items[appleTypes]; apples[0] = new Items(”Granny

Smith", 22);

Lecture 16: Visualizing and Using Arrays

Initializing Array of Objects

Items[] apples = new Items[3];

apples ->

0 1 2 null

null

null

Lecture 16: Visualizing and Using Arrays

Initializing Array of Objects

Items[] apples = new Items[3];apples[2] = new Items(“Granny Smith”, 22);

apples ->

0 1 2

null

null

G r a n n y S m i t h

name 22 (amount)

Lecture 16: Visualizing and Using Arrays

Initializing Array of Objects

Items[] apples = new Items[3];apples[2] = new Items(“Granny Smith”, 22);apples[0] = apples[2];

apples ->

0 1 2

null

G r a n n y S m i t h

name 22 (amount)

Lecture 16: Visualizing and Using Arrays

Visualizing an Array of Objects

...apple[0].setName("McIntosh”);apple[1].setAmount(10);

apples ->

0 1 2

M c I n t o s h

G o l d e n D e l i c i o u s

G r a n n y S m i t h

name 30 (amount)

name 10 (amount)

name 22 (amount)

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 ->

0 1 2

M c I n t o s h

G o l d e n D e l i c i o u s

G r a n n y S m i t h

name 30 (amount)

name 10 (amount)

name 22 (amount)

tmp

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 ->

0 1 2

M c I n t o s h

G o l d e n D e l i c i o u s

G r a n n y S m i t h

name 30 (amount)

name 10 (amount)

name 22 (amount)

tmp

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 ->

0 1 2

M c I n t o s h

G o l d e n D e l i c i o u s

G r a n n y S m i t h

name 30 (amount)

name 10 (amount)

name 22 (amount)

tmp

Lecture 16: Visualizing and Using Arrays

Swapping Integers

// swap a & bpublic 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

BlueJ Examples

Problems1. Extend Inventory class for tracking

Items

Lecture 16: Visualizing and Using Arrays

More Questions?