Day17: Arrays

 Arrays

In Java just like C and C++ arrays are collection of similar types of Data element stored at continuous memory locations. But there are few more properties associated with arrays and they are - 
  1. In Java Arrays are Object
  2. Since Array are object they are always created dynamically using the keyword "new".
  3. Since arrays are object they always live in heap area in memory.
  4. Since arrays are object we require an array reference to access them.

Creating an Array :

1 - Creating array reference 

<data_type>[ ] <array ref>;
OR
<data_type><array_ref>[ ];

2- Creating the Actual Array

<array_ref> = new<datatype>[size];

int [ ] arr; (Read as : arr is a reference to an integer array)
arr = new int[10];
OR
int[] arr = new int[10];



Accessing the Array:

class ArrayDemo
{
public static void main(String [ ] args)
{
int [ ] arr = new int[5];
arr[0] = 15;
System.out.println(arr[0]);
arr[1] = 20;
System.out.println(arr[1]);
arr[5] = 50;
System.out.println(arr[5]);
}
}

Output : 
Shown in the figure:


Exception in thread "main" java.lang.ArrayIndexoutofBoundException index 5 out of bonds for length 5 at ArrayDemo.main(ArrayDemo.java)

//Problem : Write a program to create an integer array of size n where n should be taken by the user. Now except values from the user in that array and finally display all the values along with their sum and average.

import java.util.Scanner;
class ArrayDemo
{
public static void main(String [ ] args)
{
int n;
int [ ] arr;
Scanner kb = new Scanner(System.in);
System.out.println("Enter Size of array ");
n = kb.nextInt();
arr = new int[n];
System.out.println("Enter " + n);
for(int i = 0; i<n; i++)
{
arr[i] = kb.nextInt();
}
int sum = 0;
for(int i = 0; i<n; i++)
{
System.out.println(arr[i]);
sum = sum + arr[i];
}
System.out.println("Sum is "+sum);
System.out.println("Average is "+(float)sum/n);
}
}
Location: India

Comments

New comments are not allowed.

Popular posts from this blog

Day 20 : Double Dimensional Array

Image
 Double Dimensional Array In Java 2D Array are used in those situations where we have to stored multiple groups of data . For Example :      Suppose we want to record marks of three student, where each student has five subject. In this case we have two solution - We can declare Three 1D array each of size 5 But the code will become difficult because we will have to handle 3 Arrays individually.  A better solution would be to take 2D array of three rows and five column. The benefit will be we will have to handle 1 array which can be handle using only 1 Loop. Type of 2D Array In Java we have two types of 2D Array. Rectangular  2D Array Jagged 2D Array Rectangular 2D Array These are those 2D array where every row contains same number of columns i.e., Length of every row contains same number of column. See Fig1. Jagged 2D Array These are those 2D Array where each rows can be of different length. See Fig2. Creating a Rectangular 2D Array 1. Creating the Array R...
Read more

What does System.out.printf( "%-15s%03d\n", s1, x) do?

What does System.out.printf( "%-15s%03d\n", s1, x) do?   First   s1   which is formatted using   %-15s . The   %   means that what follows is an argument that will be formatted. Then follows a   -   resulting in left alignment.   15   fills the string up to a length of 15 characters (adding spaces at the end). Finally the   s   means, that you are formatting a string. Second  x  which is formatted using  %03d . Here the  0  is the fill character, meaning that, if necessary, zeros are added. The  3  is again the width, meaning the fill character  0  is added as many times as necessary to make it 3 digits long (this time at the beginning). Finally  d  means, that a integer is formatted. OR "%-15s" means that within 15 blank space, the String "s1" will be filled in the left. (fill in the blanks from the left) "%03d" means that within 3 0s, the integer"x" will be filled in the ...
Read more

Day22 : Object Initialization

Image
 Object Initialization The word object initialization in Java means assigning initial value to instance variable at the time of creation of the object. In Java we've three ways of doing this Using Explicit initialization Using Constructor Using Initializer block 1 - Using Explicit Initialization          class < class-name>          {               <array> <data_type> <var> = value(This is an explicit initialization);          } Example : File Name : Account.java public class Account { private int accId = 101 ; private String custName = "Amit" ; private double balance = 50000.0 ; public void showAccount () { System . out . println ( "accId " + accId ); System . out . println ( "Customer Name " + custName ); System . out . println ( "Balance " + balance ); } } File Name : UseAccount.java public clas...
Read more