Can we break immutable class in Java?

So, even though, the field which is pointing to Date or Collection or array object is final, you can still break the immutability of the class by breaking Encapsulation by returning a reference to the original mutable object.

Can reflection break immutable class in Java?

And that is reflection. Since one can access and modify private fields through reflection, it can break the sanctity of the immutable object.

Can immutable class be extended?

String literal is immutable object.....why because once its object is created it can never be changed or modified! An immutable class supposed to be final so that it can't be extended.

Can we modify immutable class in Java?

Immutable class/object is the one whose value cannot be modified. For example, Strings are immutable in Java i.e. once you create a String value in Java you cannot modify it. Even if you try to modify, an intermediate String is created with the modified value and is assigned to the original literal.

Can we serialize immutable class?

It turns out you can serialize immutable objects because there's no requirement that there be a public no-argument constructor.

Immutable Classes and Objects in Java

Should dto be Serializable?

An Object needs to be serialized before being stored in a database because you do not and cannot wish to replicate the dynamically changing arrangement of system memory.

Can Final fields be serialized?

By implementing Serializable the BusinessCard class can already be serialized. To illustrated the problem with final fields we will implement the serialization and deserialization methods writeObject() and readObject() by hand. Serializing the data of our BusinessCard class is straightforward.

Can immutable class be cloned?

Immutable objects are objects that don't change. You make them, then you can't change them. Instead, if you want to change an immutable object, you must clone it and change the clone while you are creating it. A Java immutable object must have all its fields be internal, private final fields.

How can we prevent immutable class?

Can we create object of immutable class in Java?

In Java, when we create an object of an immutable class, we cannot change its value. For example, String is an immutable class. Hence, we cannot change the content of a string once created. Besides, we can also create our own custom immutable classes.

Is immutable class is final?

He differentiates between strong immutability (class is made final) and weak immutability (methods are individually and explicitly declared final rather than declaring class final).

Can we create immutable class without final keyword?

The problem with an immutable class not being final is that, subclasses may not be immutable. Here is an example from the Java API, java. lang. String is immutable and final, if a string is passed to one of your methods you can be sure that it will remain in a consistent state.

Why all wrapper classes are immutable in Java?

It is because all primitive wrapper classes (Integer, Byte, Long, Float, Double, Character, Boolean, and Short) are immutable in Java, so operations like addition and subtraction create a new object and not modify the old.

Why Sting is immutable in Java?

The String is immutable in Java because of the security, synchronization and concurrency, caching, and class loading. The reason of making string final is to destroy the immutability and to not allow others to extend it. The String objects are cached in the String pool, and it makes the String immutable.

Are all Strings immutable in Java?

The String is immutable, so its value cannot be changed. If the String doesn't remain immutable, any hacker can cause a security issue in the application by changing the reference value. The String is safe for multithreading because of its immutableness.

How can we stop clone of singleton class?

Prevent Singleton Pattern From Cloning

To overcome the above issue, we need to implement/override the clone() method and throw an exception CloneNotSupportedException from the clone method. If anyone tries to create a clone object of Singleton , it will throw an exception, as shown in the below code.

How can we prevent immutable class from reflection?

In my code, how can I prevent an immutable class being changed with reflection? Look into SecurityManager . Unless you are letting unknown people add plugins to something that you're creating, you shouldn't need to worry about this.

What is deep copy in Java?

Whenever you try to create a copy of an object, in the deep copy all fields of the original objects are copied exactly, in addition to this, if it contains any objects as fields then copy of those is also created (using the clone() method).

What is clone in Java?

The Java Object clone() method creates a shallow copy of the object. Here, the shallow copy means it creates a new object and copies all the fields and methods associated with the object. The syntax of the clone() method is: object.clone()

Can we override clone method?

When we override the clone() method inside the Programmer class, we need to explicitly take care of this List, otherwise, both original and cloned objects will point to the same Collection in the Java heap, which means, any change e.g. adding a new Certification in the original object will also reflect in a cloned ...

Why is deep copy important for immutability?

Deep copying offers us true object immutability. We can change any value in an object—no matter how deeply nested it is—and it won't mutate the data we copied it from.

How can I make my POJO class immutable?

Can we serialize static variables?

In Java, serialization is a concept using which we can write the state of an object into a byte stream so that we can transfer it over the network (using technologies like JPA and RMI). But, static variables belong to class therefore, you cannot serialize static variables in Java.

Can we use transient with final?

transient and final : final variables are directly serialized by their values, so there is no use/impact of declaring final variable as transient. There is no compile-time error though.

Why transient is used in Java?

Why is Transient modifier used? Transient in Java is used to indicate that a field should not be part of the serialization process. The modifier Transient can be applied to member variables of a class to turn off serialization on these member variables. Every field that is marked as transient will not be serialized.