Chapter 7, Problem 2FTE

Program Plan Intro

Array:

An array is defined as a group that consists of similar data types.

• The array size must be specified by an “int” value and not long or short.
• In Java, all arrays are allocated dynamically.
• An array is always indexed, starting from 0.

Declaration of an array Variable:

• An array variable is declared with [] after the data type.
• The following is the syntax for declaring an array variable.
  • elementType[] arrayRefVar;

    or

  • elementType arrayRefVar[];
• Both the above given statements can be used, but the former one is mostly used.
• The element type can be any data type and the same data type must be used by all the elements.
• The values are given inside the initialization list, the list is given inside the braces.

Example:

int[ ] arr;

char[ ] arr;

Array with initialization list:

int[ ] arr = {1, 2, 3, 4};

Declaring an array reference and creating an array:

• To insert elements to an array, first an array has to be created by using new operator and then the reference variable is assigned.
• The syntax is as follows,

arrayRefVar = new elementType[arraySize]

• From the above statement it is clear that, an array is created using new elementType[arraySize] and then the reference to the newly created array is assigned to the variable arrayRefVar.
• It is possible to declare an array variable, create an array and assign the reference to a variable in a single statement itself.

The syntax will be as follows,

elementType[]arrayRefVar = new elementType[arraySize];

elementType arrayRefVar[]= new elementType[arraySize);

Example:

double myFile = new double[20];

• The statement given above declares an array variable myFile and then creates an array that consists of 20 elements which are of the datatype double and at last assign the reference to myFile.