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Array in Java: Types, Operations, Pros & Cons

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19th Oct, 2020
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Array in Java: Types, Operations, Pros & Cons

Java is the second most popular programming language in the world, after Python. When it comes to development, particularly the development of websites and software, no language beats Java for miles.

Java is an object-oriented language, and its popularity is primarily augmented by the fact that it contains several elements that make the task of programming easy and understandable. Java is an easy language to learn for beginners and includes functionalities that can allow veterans to make the most complex of applications is a minimal amount of time.

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Arrays in Java

A Java array is a type of object in Java, known as a container object. It is used to contain objects of a single type as a part of a single set. The data type of all the array elements in Java is the say, be it textual, integral, or decimal. To create a Java array, the programmer must first know what the length of the array is going to be. The length of the array in Java cannot be increased after the array has been created. 

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Advantages of Arrays

Using an array in Java has a number of different advantages, some of which are listed below.

1. An array in Java follows the principle of the dynamic allocation of data. In dynamic allocation, the elements of the Java array are created in such a way that memory utilization is low. It makes an array in Java particularly lightweight when it comes to computational power. 

2. The primary reason for the existence of arrays is the fact that they enable multiple elements and values to be stored under a single name. Different variables do not need to be created for the storage of different values, and they can be stored in different indices of the same object. It makes the task of calling these values extremely convenient. Alongside this, it also allows for tasks such as the arrangement of values in a particular order to be called later.

3. The location of elements in arrays is extremely easy. Imagine having to store different values under different variable names and recall those names whenever you need to use those values. This would make the whole task of coding very tedious. In arrays, all you need to know is the location of the value which you need to call.

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Values are stored in adjacent locations, and you can even write a small code to locate a particular value you’re looking for, as well as know its location.

4. A very important limitation of primitive data types is the fact that values cannot be stored in contiguous memory locations. This problem is solved by using arrays, in which the Java array occupies dynamic memory in which individual elements are stored in contiguous locations, one after the other. 

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5. If you have a large amount of data that you need to store, having different data variables can be not just tedious but impossible to manage. However, arrays can store a large amount of data that needs to be stored or analyzed. The only condition while storing this data is that all the data must be of the same type. 

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Disadvantages of Arrays

As with most other elements of programming in Java, arrays also have their disadvantages. These disadvantages are listed below.

1. The Java array needs to be declared with a given array. It is not possible to declare an array without knowing what the array’s size is going to be. Programmers are often faced with situations in which it is not known what the size of data is or is going to be, or arrays need to be declared as placeholders for data that is coming in continuously. The array object is not useful under such circumstances.

2. The size of the array in Java also cannot be increased or decreased. This means that if programmers receive any amount of data that has to be added to an array once it has been declared, and all the elements of the array already hold some value, it is not possible to add data to the array.

In the best case, the data can be added to another array, and the two arrays can be concatenated, but that process leads to the formation of a third concatenated array, which leads to problems of its own.

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3. As per the definition of arrays, they can only store data of a single type. This leads to issues when different data types of the same kind need to be stored in the same place, for example, integral and float type values. This is not possible with arrays, and other objects need to be declared to satisfy this need of programmers.

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4. If arrays of a larger size than is required are declared, the memory may be wasted. In programming, memory is an all-important consideration. Memory wastage is very frequent when using arrays since once they have been declared, they hold memory locations of a fixed size. This can lead to issues when it comes to the speed and the performance of the code.

5. One of the advantages of using arrays is that elements can be located conveniently. It is important to note that this process is more convenient than if these elements were stored in different memory locations.

However, if the index of a particular element is not known, the code often needs to traverse the whole length of the data up to that element to locate it. This is an extremely inefficient process, especially when large amounts of data are involved. It can considerably increase the processing time of the code and reduce its performance.

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Defining Arrays in Java

The process of defining arrays in Java is an eBay process. However, there are a few prerequisites for defining an array. Before an array is defined, the programmer must know the data type of the elements that will be stored in the array and the name of the array variable. The syntax for the same is as follows.

datatype variablename []


datatype [] variablename

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Declaring Arrays in Java

To use an array, you need to declare the array. To declare an array, you need to know the name of the array that you want to declare, its data type, and the number of elements that are going to be stored in the array. After that, you may declare an array in two ways. The first way is to assign values to each element of the array individually. You can also use loops or other Java elements and functionalities to add data to the array.

int intArray[]; //declaring array

intArray = new int[20]; // allocating memory to array

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Types of Arrays

Three types of arrays can be declared in Java.

  1. One Dimensional Array: One-dimensional array is strings of data stored in a single line. One dimensional array only contains one continuous row of data. The elements of one-dimensional arrays can be added or printed in a single line using loops.
  2. Two Dimensional Arrays: Two-dimensional arrays are the more frequently used type of array in Java. They form a matrix of rows and columns and find applications in a lot of fields outside development, such as simulation, robotics, and machine learning. 
  3. Multi-Dimensional Arrays: Arrays can also have more than two dimensions. While arrays with multiple dimensions are not easy to visualize, their applications are only increasing by the day. They can also hold large amounts of data, which is a useful feature when it comes to data analysis. 

Operations on Arrays

Arrays are not merely data storage objects. You can also carry out mathematical operations among arrays. This is an important feature when two arrays in the same code are interrelated, or for operations such as finding the difference between points on a cartesian plane, which is also an array. The operations of addition, multiplication, division, and subtraction can be carried out using single-line commands in Java.

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This article established the importance of arrays in Java. They are essential storage objects which make the experience of coding in Java very easy for programmers. They can store large amounts of data, which is easy to locate and manipulate. Mathematical operations can also be carried out using arrays. 

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Rohan Vats

Blog Author
Software Engineering Manager @ upGrad. Passionate about building large scale web apps with delightful experiences. In pursuit of transforming engineers into leaders.

Frequently Asked Questions (FAQs)

1What is the difference between an array in C++ and that in Java?

When an array is declared in C++, space or memory is also allocated for it. But when an array is declared in Java, no storage or memory for the array is allocated – only a pointer to an array is created. Memory is allocated for the array when the keyword new is used in the declaration. In Java, an array knows its size, while in C++, it does not. And in case of out of bounds error, Java notifies the programmer automatically, but C++ does not do the same. In C++, you can create an array of objects in a single command, whereas it requires multiple commands in Java.

2How is C different from Java?

The first and most fundamental difference between C and Java is that the former is a procedure-oriented programming language that does not support object-oriented concepts, while Java is object-oriented. C is a compiled programming language that converts codes into low-level machine language that the system understands. On the other hand, Java is an interpreted language that is first converted into bytecode which is executed by the Java Virtual Machine. Java is a high-level coding language, while C is a low-level language. While Java is independent of the underlying platform and follows a bottom-up approach, C follows a top-down approach and is an entirely platform-oriented language.

3What data structures are the most important in Java?

Data structures are the basic building blocks of any programming language, and Java is no exception to this. Data structures, along with algorithms, constitute the whole programming language. The Java API offers in-built support for the most commonly-used data structures that are vital to developing programs. These data structures include arrays, sets, linked lists, maps, hash tables, stacks, and queues, which are core to the Java programming language and can significantly influence the performance of Java programs. There are many other data structures in Java apart from these basic ones.