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Copy Array In Java: Java Explained

Table of Contents

Copying arrays in Java can be a tricky process. This article will guide you through the different ways of copying an array in Java and explain each approach in detail.

Overview of Copying Arrays in Java

Java has various methods to copy an array from one location to another. Typically, this is done to create an exact duplicate of the array. Each copying approach has its own characteristics which must be taken into account when choosing the best technique for a given situation.

The most common methods for copying an array are the System.arraycopy() method, the clone() method, and the Arrays.copyOf() method. The System.arraycopy() method is the most efficient way to copy an array, as it allows for the copying of a range of elements from one array to another. The clone() method creates a shallow copy of the array, meaning that the elements of the array are copied, but any objects contained within the array are not. Finally, the Arrays.copyOf() method creates a deep copy of the array, meaning that all elements and objects contained within the array are copied.

Different Approaches to Copy an Array in Java

When it comes to copying an array in Java, there are several different approaches. We will go over the different approaches to copying an array below.

The most common approach is to use the System.arraycopy() method. This method allows you to copy an array from one location to another. It is a fast and efficient way to copy an array.

Another approach is to use the clone() method. This method creates a shallow copy of the array, meaning that the elements of the array are copied, but the references to the objects in the array are not.

Using the Arrays Class

The Arrays class in Java is a utility class which contains several static methods that can be used to manipulate arrays. These methods can be used to copy an array by calling the System.arraycopy() method. The syntax for this method is as follows:

Arrays.copyOf(array, length);

The array parameter is the source array and the length parameter is the length of the copy to be made. This method copies the source array into a new array of length equal to the length parameter and returns the newly created array.

In addition to the copyOf() method, the Arrays class also provides other methods for manipulating arrays such as sort(), binarySearch(), and fill(). These methods can be used to sort an array, search for an element in an array, and fill an array with a specified value respectively.

Using System.arraycopy() Method

The System.arraycopy() method is a native Java method which can be used to copy an array from one location to another. The syntax for this method is as follows:

System.arraycopy(source, source_pos, dest, dest_pos, length);

The source parameter is the source array and the source_pos parameter is the starting index of the source array. The dest parameter is the destination array and the dest_pos parameter is the starting index of the destination array. The length parameter is the number of elements to be copied. This method copies the source array into the destination array at the specified positions and returns nothing.

The System.arraycopy() method is a useful tool for copying arrays quickly and efficiently. It is important to note that the source and destination arrays must be of the same type, and the length parameter must not exceed the length of the source array. Additionally, the source and destination arrays must not overlap, as this will cause unexpected results.

Using Java 8 Streams API

Java 8 introduced the Streams API which provides a functional way to process and manipulate collections of data. The Streams API can be used to copy an array by calling the Arrays.stream() method with a lambda expression. The syntax for this method is as follows:

Arrays.stream(array).mapToInt(i -> i).toArray(); 

The stream() method creates a stream of the source array elements and the lambda expression converts each element into an integer. This can also be done with other primitive types as well. Finally, the toArray() method returns a newly created array containing all of the elements in the stream. This method copies the source array into a new array and returns it.

The Streams API is a powerful tool for manipulating data in Java 8. It can be used to perform a variety of operations on collections of data, such as filtering, mapping, and sorting. Additionally, the Streams API can be used to perform operations on primitive types, such as integers and doubles. With the Streams API, developers can quickly and easily manipulate data in a functional way.

Implementing the Cloneable Interface

Another way to copy an array in Java is to use the Cloneable interface. The Cloneable interface is an interface which can be implemented by classes that provide deep cloning support. The syntax for this interface is as follows:

 public class MyClass implements Cloneable {    public Object clone() throws CloneNotSupportedException {          return super.clone();     }     } 

The clone() method is implemented which returns a shallow copy of the current object. This method can be used to copy an array by calling the clone() method on each element of the source array and then inserting the newly copied element into a new array.

It is important to note that the clone() method does not perform a deep copy of the array. This means that any changes made to the original array will be reflected in the cloned array. Therefore, it is important to ensure that the cloned array is not modified in any way. Additionally, the clone() method should be used with caution as it can lead to unexpected results if not used correctly.

Conclusion

In this article, we have gone over several approaches to copying an array in Java. Each approach has its own benefits and drawbacks so it is important to choose the best technique for each situation. The most commonly used approach is to use the Arrays class or System.arraycopy() method. If a deep copy of an array is needed, then the Cloneable interface can be used to achieve this.

It is important to note that when using the Arrays class or System.arraycopy() method, the source array and the destination array must be of the same type. If the types are different, then a ClassCastException will be thrown. Additionally, when using the Cloneable interface, the clone() method must be called on the source array in order to create a deep copy.

Sarang Sharma

Sarang Sharma

Sarang Sharma is Software Engineer at Bito with a robust background in distributed systems, chatbots, large language models (LLMs), and SaaS technologies. With over six years of experience, Sarang has demonstrated expertise as a lead software engineer and backend engineer, primarily focusing on software infrastructure and design. Before joining Bito, he significantly contributed to Engati, where he played a pivotal role in enhancing and developing advanced software solutions. His career began with foundational experiences as an intern, including a notable project at the Indian Institute of Technology, Delhi, to develop an assistive website for the visually challenged.

Written by developers for developers

This article was handcrafted with by the Bito team.

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