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92. 'length' array attribute






'length' array attribute will tell us the size of an array (i.e. the number of elements that an array can hold).

Lets implement this on Eclipse IDE:

1. Create 'ArrayLengthDemo' class under any project as shown below:



2. Declare two arrays as shown below:



3. Print the size of the declared array variables a[] and b[] as shown below:



4. Save and Run the 'ArrayLengthDemo' class 
5. Observe that the output is displayed in console as shown below:



Download this project:

Click here to download the project containing the class file used in this post (You can download the project and import into Eclipse IDE on your machine)

The above example is just for your understanding. Lets create some real time example where you can use this length attribute.

Lets implement the following program on Eclipse IDE 

Program: Assign and print the values of array variable with the help of 'length' attribute.

1. Create 'AssingAndPrint' class under any project as shown below:



2. Create an array a[] as shown below:



3. Assign values to all the elements in the array using for loop and length attribute as shown below:



4. Print the values of all the elements in the array a[] using for loop and length attribute as show below:


5.Save and Run the 'AssignAndPrint' class
6. Observe that the output is displayed in the console as shown below:



Download this project:

Click here to download this project containing 'AssignAndPrint' class file used  in this project (You can download this project and import into Eclipse IDE on your machine)




Please comment below to feedback or ask questions.

'Nested Classes' will be explained in the next post.




4 comments:

raghavi said...

Hello arun

here u dint create any class or method with length then how can we take a.length?

Arun Motoori said...

@Raghavi - length variable will be automatically created when an array is created. length is a final type variable which holds the size of the array and the value of the length cant be changed.

For example - if we have created the array of size 15 as shown below -

int a[] = new int[15];

Java automatically create a final type variable 'length' with the size of the array assigned to it.

So you can directly use the length variable as explained in the post.

viki said...

In step 4,
without below mentioned code also we can get the same output:
for(int i=0;i<a.length;i++)
{
a[i]=i;
}

are there any specific reason for that?

Arun Motoori said...

@viki - Without the mentioned code we get the below output -

The value assigned to a[0] is 0
The value assigned to a[1] is 0
The value assigned to a[2] is 0
The value assigned to a[3] is 0
The value assigned to a[4] is 0
The value assigned to a[5] is 0
The value assigned to a[6] is 0
The value assigned to a[7] is 0
The value assigned to a[8] is 0
The value assigned to a[9] is 0

i.e. All the values of the variables printed as 0 as we have not assigned any values to the array elements.

In step4, I have assigned the values to the array elements using the code you have mentioned:

By mentioning this code in the program, I will get the output as:

The value assigned to a[0] is 0
The value assigned to a[1] is 1
The value assigned to a[2] is 2
The value assigned to a[3] is 3
The value assigned to a[4] is 4
The value assigned to a[5] is 5
The value assigned to a[6] is 6
The value assigned to a[7] is 7
The value assigned to a[8] is 8
The value assigned to a[9] is 9

i.e. The value 0 is assigned to first element, value 1 assigned to second elements,....etc are printed in the output.

Hope I clarified your doubt.

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