This document discusses arrays in Java. It defines an array as a fixed-size collection of elements of the same type that can store a collection of data. It describes how arrays allow storing multiple variables of the same type at once. The document covers declaring, constructing, initializing single and multi-dimensional arrays, and gives an example of how arrays can solve the problem of needing to store exam scores for 100 students.

1. PROGRAMMING IN JAVA
Arzath Areeff

2. WHAT IS ARRAY?
Java provides a data structure, the array, which
stores a fixed-size sequential collection of
elements of the same type. An array is used to
store a collection of data, but it is often more
useful to think of an array as a collection of
variables of the same type.

3. ARRAYS
• DECLARATION
• CONSTRUCTION
• INITIALIZATION
• TWO DIMENSIONAL ARRAY
• MULTI DIMENSIONAL ARRAY

4. WHY ARRAY?
Problem?
• Implement an application that will calculate 100
students exam average.
• Variables needed?
int studentA;
int studentB;
int studentC;
int studentD;
...

5. SEVERAL VARIABLES AT ONCE?
Array comes to the rescue!
• Just a list of variables
• Declare the array
int [] array;
• Initialize the array and set it's size
array = new array[3];
• Store values into array
array[0] = 2;
array[1] = 3;
array[2] = 7;

6. DECLARATION
• Declaring Arrays:
Int[] mark;
Byte[] age;
Double[] height;
Int mark[];
Byte age[];
Double height[];
Data type
Array Name
works but not preferred way
preferred way

7. DECLARATION COUNT…
• Array declaration in C++
int hardy[10];
• Array declaration in Java
int [] hardy;
hardy =new int[10];

8. DECLARATION COUNT…
• Storage for the array itself is not allocated
until you use “new”.
• For initializing method the “new” command is
not needed.
int [] hardy={5,3,7,89,2};

9. CONSTRUCTION
Int [] hardy;
hardy=new int[5];
In single line
Int[] hardy=new int[5];
Hardy array

10. INITIALIZATION
• Initialization is loading the array with the valies.
Int[] hardy=new int[5]
hardy[0]=32;
hardy[1]=12;
hardy[2]=66;
hardy[3]=54;
hardy[4]=43;
32 12 66 54 43
0 1 2 3 4
index

11. TWO DIMENSIONAL ARRAY
• Int[][] hardy=new int[2][3];
hardy[0][0]=32;
hardy[0][1]=12;
hardy[0][2]=66;
hardy[1][0]=54;
hardy[1][1]=43;
hardy[1][2]=36;
32 12 66 54 43 36
0 1
0 1 2 0 1 2

12. TWO DIMENSIONAL ARRAY - NON
UNIFORM
• Int[][] hardy=new int[2];
• Mark[0]=new int[3];
• Mark[1]=new int[4];
0 1
0 1 2 0 1 2 3

13. MULTI DIMENSIONAL ARRAY
• Int[][][] hardy=new int[2][3][2];
0 1
0 1 2 0 1 2
0 1 0 1 0 1 0 1 0 1 0 1

14. Peace & Love