Java arrays

Java arrays

• 1.
  Arrays  Array isa collection of similar type of elements that have contiguous memory location.  In java, array is an object the contains elements of similar data type.  Array is index based, first element of the array is stored at 0 index.
• 2.
   Types ofArray  Single Dimensional Array  Multidimensional Array Declaration of Arrays – 3 steps  Declare the array  Create storage area in primary memory.  Put values into the array (i.e., Memory location) Declaration of Arrays: 1 step Form 1: Type arrayname[] Form 2: Type [] arrayname;
• 3.
   Creation ofarrays: 2 step arrayname = new type[size]; // create a memory  Initialization of arrays: arrayname [index/subscript] = value; or {list of values};  Example: int [] students = new int[7]; int [] students = {1,2,3,4,5};  Two Dimensional Arrays:  array with two subscript operator – [] [] datatype [] [] array_name=new datatype [row][column]; int [] [] student=new int[2][2]; int tableA[2][3] = {{10, 15, 30}, {14, 30, 33}}; int tableA[][] = {{10, 15, 30}, {14, 30, 33}};
• 4.
  4 Variable Size Arrays Java treats multidimensional arrays as “arrays of arrays”. It is possible to declare a 2D arrays as follows: – int a[][] = new int [3][]; – a[0]= new int [3]; – a[1]= new int [2]; – a[2]= new int [4];
• 5.
  import java.io.*; class B{ publicstatic void main(String args[]){ try{ //int[] a={1,2,3,4,5,6,7,8,9,10}; int a[]={1,2,3,4,5,6,7,8,9,10};//declaration, instantiation and initialization //printing array for(int i=0;i<a.length;i++)//length is the property of array System.out.println(a[i]); int b[]=new int[50]; DataInputStream dis=new DataInputStream(System.in); System.out.println("Enter the no"); int c=Integer.parseInt(dis.readLine()); for(int j=0;j<c;j++)//length is the property of array {b[j]=Integer.parseInt(dis.readLine());} System.out.println("Entered Numbers are:"); for(int j=0;j<c;j++)//length is the property of array {System.out.println(b[j]);}} catch(Exception e) { }}}
• 6.
  import java.io.*; class B1{ publicstatic void main(String args[]){ try{ int arr[][]={{1,2,3},{2,4,5},{4,4,5}}; //declaring and initializing 2D array for(int i=0;i<3;i++){ for(int j=0;j<3;j++){ System.out.print(arr[i][j]+" ");} System.out.println(); } int [][] f=new int[10][10]; DataInputStream dis=new DataInputStream(System.in); System.out.println("Enter the row and column values"); int c=Integer.parseInt(dis.readLine()); int d=Integer.parseInt(dis.readLine()); for(int i=0;i<c;i++){ for(int j=0;j<d;j++){ f[i][j]=Integer.parseInt(dis.readLine());}} System.out.println("2D-array"); for(int i=0;i<c;i++){ for(int j=0;j<d;j++){ System.out.print(f[i][j]+ " " );} System.out.println(); }} catch(Exception e) {}}}