Array Data Structure in Java (Java-Arrays)

Array Data Structure in Java (Java-Arrays)

Java provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

Instead of declaring individual variables, such as number0, number1, …, and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and …, numbers[99] to represent individual variables.

This tutorial introduces how to declare array variables, create arrays, and process arrays using indexed variables.

See Arrays in C++

Declaring Array Variables

To use an array in a program, you must declare a variable to reference the array, and you must specify the type of array the variable can reference. Here is the syntax for declaring an array variable −

Syntax

Note − The style dataType[] arrayRefVar is preferred. The style dataType arrayRefVar[] comes from the C/C++ language and was adopted in Java to accommodate C/C++ programmers.

Example

The following code snippets are examples of this syntax −

Creating Arrays in Java

You can create an array by using the new operator with the following syntax −

Syntax

The above statement does two things −

  • It creates an array using new dataType[arraySize].
  • It assigns the reference of the newly created array to the variable arrayRefVar.

Declaring an array variable, creating an array, and assigning the reference of the array to the variable can be combined in one statement, as shown below −

Alternatively you can create arrays as follows −

The array elements are accessed through the index. Array indices are 0-based; that is, they start from 0 to arrayRefVar.length-1.

Example

Following statement declares an array variable, myList, creates an array of 10 elements of double type and assigns its reference to myList −

Following picture represents array myList. Here, myList holds ten double values and the indices are from 0 to 9

Arrays In Java

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Raza Bayani
Raza Bayani 42 posts

<p>Raza Bayani studies BCE (Bachelor in Computer Engineering) in Poly-technical University of Kabul. He is the CEO of CODEJOW group, a web designer, coder and recently a blogger. Raza thinks, he can help others and also boost-up his own programming skills being on codejow.com.</p>

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