Announcements

1
Announcements Review

• Last Time Lots of objects
• Array example
• Shapes shapes
• shapes new Shapes2
• shapes0 new Shapes(4,4,)
• shapes1 new Shapes(14,4,lt3)
• Today Simpler array usages
• Boolean choices new Boolean5
• for (i 0 i lt choices.length i)
• choicesi true

• Announcements
• Lab 4 FlightReservation
• Defining classes
• Due
• Thursday 10pm

2
Arrays are like strings Visualizing strings

• String myApples new String("apples")
• String myApples -gt

a p p l e s
0 1 2 3 4 5
3
Visualizing Arrays

• int appleInventory 3, 10, 99
• appleInventory -gt

3 10 99
0 1 2
4
Visualizing Arrays

• String appleNames "McIntosh", "Golden
  Delicious", "Granny Smith"
• appleNames -gt

0 1 2
G r a n n y S m i t h
G o l d e n D e l i c i o u s
M c I n t o s h
5
BlueJ Examples

• Problem We want to track apple inventories. We
  want to track apple names and amounts in
  inventory.
• one array stores apple names
• one stores integer amounts in inventory

6
Limitations of Arrays

• You cannot change the size of an array once you
  create it, i.e.,
• String names new String70
• To make a bigger array, first allocate a larger
  array, and then copy the first array to it
• String moreNames new String100
• for (int i 0 i lt names.length i)
• moreNamesi namesi
• // if needed you can names moreNames

7
Limitations of Arrays

• You cannot compare arrays with
• for (int i 0
• (i lt names.length) (i lt
  moreNames.length) i)
• if (!moreNamesi.equals(namesi))
• return false
• return true
• Similarly, you have to iterate over the array to
  print it
• for (int i 0 i lt names.length i)
• System.out.println(namesi)

8
More Questions?