If you have entered the intermediate level of your Java Programming Course, you might know about the ArrayList Concept well. However, the Creation and Maintenance of any Declared ArrayList are expensive. In such cases, “Java Deep Copying Of ArrayList” can be a good alternative.
In ArrayList, we can find numerous advantages, which is why many Java developers always use the ArrayList. However, intensive use of the ArrayList in any application can also bring many other problems. As a student of Computer Science, you should be aware of such practices.
This article will focus on the Basics of the Copying Policies of ArrayList in Java and more on Deep Copy Policy. Later in this article, we will discuss some practical implementation processes to deal with Java Deep Copying. So, let us start our discussion.
TL;DR: Deep Copying Of Java ArrayList
Aspect | Summary |
Copy Types |
|
Preferred Methods | Deep Copy is more reliable for real-world applications as it avoids shared references and side effects. |
Implementation Ways |
|
Real-world Applications |
|
Performance Implications |
|
Common Mistakes | Forgetting to clone inner elements, Deep copying immutable objects unnecessarily, mishandling nulls and nested references, etc. |
Challenges | Managing complex object graphs, handling cyclic dependencies, Serialization overhead, etc. |
What Are The Different Methods For Creating A Copy Of The List In Java?
In your Computer Science Course in Java Programming, if you are working with the ArrayList, you should be aware of the process to copy the ArrayList. If you have declared any New ArrayList in your application, to reduce the maintenance cost, you should have to use some copying processes.
Still have no clue about the topic and you want to get a deeper understanding with an expert Java tutor, then you can contact us for the same.
In Java Programming, we have two different kinds of Copying Processes. One is the Shallow Copy and another is the Deep Copy. Let us start with the Shallow Copy first.
1. Java Shallow Copy Technique:
In Shallow Copy, when you are going for the ArrayList Clone, it will create the Object State of every element in the list. Then the Copied List will refer to the Same Original Objects which are declared earlier. That means in this case, there is no separate object state is declared.
Hence, for the Shallow Copy method, we are not going to get the changed Object State for the Copied List. That is the reason, the Shallow Copy is used very less than the Deep Copy. Let us check the following code snippet example which creates the Shallow Copy.
public class Main{
public static void main(String[] args){
Main ShallowCopy = Values;
}
}
2. Java Deep Copy Technique:
Now, after the Shallow Copy, it is time to discuss the Deep Copy Process. The Deep Copy Process is the complete opposite of the Shallow Copy. In the Deep Copy, a New Object will be created for each element in the ArrayList Clone.
That means, there will be two different states of the Objects. One is for the Original List and another is for the ArrayList Clone. This makes it easy to handle objects in the Array List. Let us check the following example where the Deep Copy of Objects will be declared.
public class Main{
public static void main(String[] args){
Main DeepCopy = new Main(Values);
}
}
What Are Different Methods For Creating A Deep Copy Of The List?
Now, after understanding the Deep Copying Process, it is time for the Practical Implementation. The Implementation of Deep ArrayList Clone can be done in various ways like third-party libraries, a serializable interface, JSON String, Apache Commons Lang, etc.
However, among them, very few are highly useable. As the Deep Process of Copying works on creating a New Instance of Cloned List, we can only use the ArrayList Clone Method and Copy Constructors. Let us first start with the Clone() Function.
Method 1: Create A Deep Copy With The Java Deep Clone Method
The Clone() is the built-in function of the Java Programming Language. With the Clone(), one can create a Cloneable Interface of the objects. Here, we are going to use the same Clone() Class to make a cloned List from the Original List.
import java.util.ArrayList;
public class Main implements Cloneable {
ArrayList<String> val; // Declaration Of New ArrayList With Private String Name
// Declaring Constructor For Initializing ArrayList
public Main() {
this.val = new ArrayList<>();
}
// Method To Add Element To The ArrayList Object
public void addName(String n) {
this.val.add(n); // Adding JSON String Values
}
// Overriding Clone() Method For Deep Copy
@Override // Creating Public Object Clone Method
protected Object clone() throws CloneNotSupportedException {
Main copied = (Main) super.clone(); // Creating A Deep Copy Object
copied.val = new ArrayList<>(this.val); // Deep Copy Of The List
return copied;
}
@Override
public String toString() {
return val.toString(); // Returning The Element
}
public static void main(String[] args) throws CloneNotSupportedException {
Main original = new Main(); // Create the Original Object
// Add Multiple Terms
original.addName("CodingZap");
original.addName("ZapOne");
original.addName("Java Code");
Main deep = (Main) original.clone(); // Develop Copy Using Clone()Method
// Printing Old ArrayList First
System.out.println("Original ArrayList: " + original);
// Printing Copied List After Original List
System.out.println("Deep Copied ArrayList Using Clone: " + deep);
}
}
Steps Of The Program:
At first, the ArrayList Package will be imported into the program.
Later, we will declare the ArrayList that will only accept the String Values.
Now, we will declare the Constructor For initializing the ArrayList.
Then, we will create a Class that will catch all the values in the ArrayList.
Now, we will create the Overriding Class for the deep copying of the new list that is created.
The Classes will have the exception like CloneNotSupportedException. So, if there is any exception occurs, it will directly catch in the program.
Now, we will create another class that will convert the ArrayList to the String for printing purposes.
Now, the Main Class will start where the instances for the ArrayList will be declared.
Later. We will insert values one by one and will invoke the Clone() with the declared obs.
At last, we will print both Cloned List and Original List one after another.
Output:
From the above example, we can see that Both Array Lists come with the same declared explicitly set. So, the New List that is declared to store the Cloned Values is working completely fine in the system. So, the above example correctly reflected the use of the Clone() Classes.
If you’re facing any difficulties checking if an array contains a given value using Java, then you can check out our article, we’ve mentioned various methods to tackle these difficulties.
Method 2: Create A Deep Copy With The Copy Constructor Function
Now, another way to create a Deep Array List Copy will be to use the Copy Constructors. Copy Constructors are a special Constructor Class. Here, the Constructor helps to implement other objects with the same objects in the same class.
The Copy Constructors take the Objects as the Parameter or Argument and then the complete process goes on. In this example, we will discuss the entire process. So, have a look at the following.
import java.util.ArrayList;
public class Main {
ArrayList<String> vals; // Declaring ArrayList String Name
// Public Constructor For Initializing The List
public Main() {
this.vals = new ArrayList<>();
}
// Declaring The Method To Add Elements To Object
public void addName(String val) {
this.vals.add(val);
}
// Declaration Of Copy Constructor For Deep Copy
public Main(Main other) {
this.vals = new ArrayList<>(other.vals); // Creating Deep Copy Of List
}
@Override
public String toString() { // Creating Override Class Instance
return vals.toString(); // Returning The Elements
}
public static void main(String[] args) {
Main original = new Main(); // Create the Original Object
// Add Multiple Terms
original.addName("Java");
original.addName("ZapOne");
original.addName("CodingZap");
Main deep = new Main(original); // Develop Deep Copy Using Copy Constructor
// Printing Old First ArrayList
System.out.println("Original ArrayList: " + original);
// Printing Copied List After Original List
System.out.println("Deep Copied ArrayList With Copy Constructor: " + deep);
}
}
Steps Of The Program:
At first, like the previous example, we have to import the Array List Package into the program.
Now, we have to declare the ArrayList that will only accept the String Values.
Later, we will declare the Constructor For initializing the ArrayList as we have done earlier.
Then, we will create a Class that will catch all the values in the ArrayList.
Now, it is time to create the Copy Constructors for the Deep ArrayList Copy. To do so, we have to share the Other instances as the argument.
Now, we will create the class that will convert the ArrayList to the String.
Later, the instances for the ArrayList will be declared in the Main Class.
Now, we will insert values one by one and use the basic syntax of the Deep ArrayList copying.
At last, we will print both Cloned List and Original List one after another.
Output:
The above output reflected that the use of the Copy Constructors is working completely fine. The First ArrayList and the Copied ArrayList are completely the same. Hence, the Program Logic and the implementation is done perfectly in this case.
Comparison Table Between Shallow Copy And Deep Copy:
Now, after understanding the practical implementation of Deep Copying a Java ArrayList, it is time to know the differences between the two methods for creating a copy of a Java ArrayList.
In this section, we will draw a Comparison Table between the Shallow Copy and Deep Copy Techniques. We will create the table using criteria like Copy Type, Memory Usage, Performance, etc.
Criteria | Shallow Copy Technique | Deep Copy Technique |
Copy Type | Reference | Object |
Independence | No | Yes |
Memory Usage | Low | High |
Performance | Fast | Slow |
Risk of Side Effects | High | Low |
Modification Impact | Global | Local |
Complexity | Simple | Complex |
What Are Some Real-World Applications Of Deep Copying Of Java ArrayList?
Now, if you are thinking that the Deep Copying of Java ArrayList is only present for some Educational Purposes, then you are thinking wrong. There are many Real-world applications of such a technique.
To make you aware of the Real-world applications, we have brought this section. In this section, we will let you know different fields where the Deep Copying of Java ArrayList is necessary.
1. Software Applications:
If you are developing software applications, such as text editors or Design Tools, you must use Java ArrayList Deep Copying. To develop the Redo and Undo functionality, this will be needed.
When To Use In Real-World Applications:
- Using this technique, we can store multiple versions of an editable list of different objects.
- Such a technique helps to prevent accidental changes in the application using Redo.
2. Data Management Systems:
Not only in Software Applications, but in Data Management Systems, the use of the Java Deep Copying ArrayList Technique can be found. In simple terms, it helps to implement Clone Functionality in the system.
When To Use In Real-World Applications:
- If you want to duplicate a configuration or setup from an ArrayList, we have to use such methods.
- When a user creates a clone, the Original Data will not be altered by the user.
3. Multi-Threaded Applications:
In Multi-Threaded Applications, Deep Copying plays an important role as Multiple Threads are working on the same data. Deep Copying helps to do Thread-Safe Data Manipulation.
When To Use In Real-World Applications:
- It helps to avoid concurrent modification issues when working with the mutable objects.
- To create a snapshot of a collection for read and write operations.
What Are Some Of The Challenges Of Deep Copying?
Till now, we believe that all the necessary points related to the Deep ArrayList Copy should become clear to you. Now, before wrapping up the discussion, we would like to shed some light on the challenges you might find while performing Deep ArrayList Copy in Java.
If you are thinking that you can work with the ArrayList whenever you want and to reduce the maintenance cost, you are going to perform Deep Copies of the List, then you are thinking wrong. Because there are numerous challenges associated with Deep Java Copy.
Problem With Complex Graphs: If the instances are interconnected, then it will cause problems when you create the Deep Java Copy. In such cases, you have to Recursively Copy all the instances at the same time. Otherwise, the Complex Graph problem can be seen.
Interconnection Instances Problem: In any application, it might be a situation in which any instance is connected with other instances. So, if you are going to copy instances make sure that the interconnection should be intact.
Cyclic Dependencies Issue: Suppose, the instances in any program are referring to each other and present in a Cyclic Manner. So, if you have put a Recursion Process there, it might run infinitely. So, you have to put the End Condition as well.
Overhead Of Serialization: If you have thought to go in a completely new way and choose the Serialization process, then you should perform Serialization to all the instances declared in the program. So, it is better not to go with the Serialization process.
Conclusion:
In the end, we can say it is very important to understand the “Java Deep Copying Of ArrayList”.
However, before jumping for the ArrayList Deep Copying Process, it will be better to have a good foundation on the Basics of Java Programming. If your Java Programming Basics are not clear, then you will find the total concept a difficult one.
Also, if are you curious to know about the difference between Array and ArrayList then you can check out our article.
Takeaways:
The use and decoration of ArrayList might be simple, but its maintenance cost is higher.
To Reduce the maintenance cost, the Deep ArrayList Copying is necessary.
The Shallow Copy will not create separate objects like Deep ArrayList Copying.
For Deep ArrayList Copy, the Clone() and Copy Constructors can be used.
The Deep ArrayList Copy can cause challenges for Complex Graph, Cyclic Dependencies, etc.
