• Aggregate Data Type
• Deal with items of same type
• Lists
  • numbers
  • words
  • (any other type)
• Analogies
  • mailboxes in PO
  • CD rack with slots
• Simplifies Naming
• Allows use of Loops
• Required for:
  • required for statistical problems
  • required for dealing with lists

• Subscripts are usually integers in brackets

x[5] = 21;

---.setText("Result is " + x[5]);

int k = 0; sum = 0;

while ( k < 10 )

{

k = k + 1;

sum = sum + name[k];

}

 
    int num[] = new int[6];
    +--+--+--+--+--+--+
num | ?| ?| ?| ?| ?| ?|
    +--+--+--+--+--+--+
      0  1  2  3  4  5 

    num[1] = 21; num[5] = 13;
    +--+--+--+--+--+--+
num | ?|21| ?| ?| ?|13|
    +--+--+--+--+--+--+
      0  1  2  3  4  5 





    int k = 2;
    while(k<6){num[k] = k*k; k = k+1;}
    +--+--+--+--+--+--+
num | ?|21| 4| 9|16|25|
    +--+--+--+--+--+--+
      0  1  2  3  4  5 
	

Declaration:

double weights[];

Definition:

weights = new double[50];

Or Combined:

double weights[] = new double[50];

• In contrast to most languages, Java checks
• Run-time cost of checking