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What does it mean for a class to be immutable?
Immutable class means that once an object is created, we cannot change its content. In Java, all the wrapper classes (like Integer, Boolean, Byte, Short) and String class is immutable. The class must be declared as final (So that child classes can’t be created)
What is an immutable class explain with example?
Example to create Immutable class The instance variable of the class is final i.e. we cannot change the value of it after creating an object. The class is final so we cannot create the subclass. There is no setter methods i.e. we have no option to change the value of the instance variable.
What is the use of immutable class?
Immutable classes make concurrent programming easier. Immutable classes make sure that values are not changed in the middle of an operation without using synchronized blocks. By avoiding synchronization blocks, you avoid deadlocks.
Is immutable class simple?
Simple Immutable Class. Let’s follow the above steps and create our own immutable class (ImmutableStudent. java). The above class is a very simple immutable class which doesn’t hold any mutable object and never expose its fields in any way; these type of classes are normally used for caching purposes.
How can we create immutable class?
To create an immutable class in Java, you have to do the following steps.
- Declare the class as final so it can’t be extended.
- Make all fields private so that direct access is not allowed.
- Don’t provide setter methods for variables.
- Make all mutable fields final so that its value can be assigned only once.
How can we break immutable class?
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.
Does final mean immutable?
final means that you can’t change the object’s reference to point to another reference or another object, but you can still mutate its state (using setter methods e.g). Whereas immutable means that the object’s actual value can’t be changed, but you can change its reference to another one.
What does an immutable class do in Java?
Immutable Class means that once an object is initialized from this Class, we cannot change the state of that object. In other words, An immutable object can’t be modified after it has been created. When a new value is needed, the accepted practice is to make a copy of the object that has the new value.
Can you change the state of an immutable class?
While dealing with immutable objects, we are not allowed to change an object’s state after its creation. Whenever the state of an object is changed, we get a new object. Immutable classes do not provide any methods for changing their content. In Immutable classes, only getter methods are available and not setter methods.
What’s the difference between a mutable and an immutable object?
mutable object – an object that is liable to change. immutable object – an object that is unchanging over time or unable to be changed. We can directly use the original definition when we put it in terms of object oriented programming. The final question is how do I use this in practice?
How is immutable the same as equal side effect free?
Immutable is not the same as equal side effect free. For example, an immutable object could produce side effects such as logging to a file. It is slightly inaccurate to say making an object immutable also makes it side effect free. – Grundlefleck Jul 18 ’10 at 20:14 @Grundleflek, I think this may be splitting hairs.