Sunday, 31 March 2013

Arrays in JAVA

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An array is a very common type of data structure where in all elements must be of the same data type.Once defined , the size of an array is fixed and cannot increase to accommodate more elements.

Using and array in your program is a 3 step process -
1) Declaring your Array
2) Constructing your Array
3) Initializing your Array Syntax for Declaring Array Variables is
int intArray[];
 // Defines that intArray is an ARRAY variable which will store integer values
int []intArray;

Constructing an Array
intArray = new int[10]; // Defines that intArray will store 10 integer values
Declaration and Construction combined
int intArray[] = new int[10];
Initializing an Array
intArray[0]=1; // Assigns an integer value 1 to the first element 0 of the array
intArray[1]=2; // Assigns an integer value 2 to the second element 1 of the array

Declaring and Initializing an Array
int intArray[] = {1, 2, 3, 4};
// Initilializes an integer array of length 4 where the first element is 1 , second element is 2 and so on.

Multidimensional Array To declare a multidimensional array variable, specify each additional index using another set of square brackets.
int twoD[ ][ ] = new int[4][5] ;

When you allocate memory for a multidimensional array, you need only specify the memory for the first (leftmost) dimension. You can allocate the remaining dimensions separately. In Java the length of each array in a multidimensional array is under your control.
int twoD[][] = new int[4][];
twoD[0] = new int[5];
twoD[1] = new int[6];
twoD[2] = new int[7];
twoD[3] = new int[8];


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