Can we create a class inside a class in Java?

Asked By: Nacimiento Altman | Last Updated: 23rd May, 2020
Category: technology and computing programming languages
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In java, it is possible to define a class within another class, such classes are known as nested classes. They enable you to logically group classes that are only used in one place, thus this increases the use of encapsulation, and create more readable and maintainable code.

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Similarly, you may ask, can you have a class within a class in Java?

The Java programming language allows you to define a class within another class. Such a class is called a nested class and is illustrated here: Non-static nested classes (inner classes) have access to other members of the enclosing class, even if they are declared private.

Beside above, can we have multiple public class within a class? Second, Yes you can have one class inside other class, these classes are called inner classes or nested classes in JAVA. JAVA file and name of the file should be same as the name of class. Once compiled, such file produces multiple . class files for each of the classes present in the .

Likewise, people ask, how do you create a class inside a class in Java?

The object of java inner class are part of the outer class object and to create an instance of the inner class, we first need to create an instance of outer class. Java inner class can be instantiated like this; OuterClass outerObject = new OuterClass(); OuterClass. InnerClass innerObject = outerObject.

What is inner class and outer class in Java?

In Java, just like methods, variables of a class too can have another class as its member. The class written within is called the nested class, and the class that holds the inner class is called the outer class. Syntax. Following is the syntax to write a nested class.

39 Related Question Answers Found

What is destructor in OOP?

Destructors. Whenever an object is destroyed and removed from memory, the object's destructor is called. In object-oriented programming, a destructor gives an object a last chance to clean up any memory it allocated or perform any other tasks that must be completed before the object is destroyed.

Can a class be static?

So, Yes, you can declare a class static in Java, provided the class is inside a top level class. Such classes are also known as nested classes and they can be declared static, but if you are thinking to make a top level class static in Java, then it's not allowed.

Can a class be private?

Answer: We can not declare top level class as private. Java allows only public and default modifier for top level classes in java. Inner classes can be private.

What is a static class?

A C# static class is a class that can't be instantiated. The sole purpose of the class is to provide blueprints of its inherited classes. A static class is created using the "static" keyword in C#. A static class can contain static members only. You can't create an object for the static class.

Can we define constructor in inner class?


5 Answers. You can observe the constructor chain for the inner class when you extend an inner class. so you can see that you are able to call the super constructor of your nested class passing to that constructor the MainClass , and calling . super on mainClass object instance.

Can a class be protected in Java?

Since there's no such concept as 'subpackage' or 'package-inheritance' in Java, declaring class protected or package-private would be the same thing. You can declare nested and inner classes as protected or private, though.

What is Polymorphism in Java?

Polymorphism in Java is a concept by which we can perform a single action in different ways. We can perform polymorphism in java by method overloading and method overriding. If you overload a static method in Java, it is the example of compile time polymorphism. Here, we will focus on runtime polymorphism in java.

What is encapsulation in Java?

Encapsulation is one of the four fundamental OOP concepts. The other three are inheritance, polymorphism, and abstraction. Encapsulation in Java is a mechanism of wrapping the data (variables) and code acting on the data (methods) together as a single unit. Declare the variables of a class as private.

What is super keyword in Java?

super is a keyword. It is used inside a sub-class method definition to call a method defined in the super class. Private methods of the super-class cannot be called. Only public and protected methods can be called by the super keyword. It is also used by class constructors to invoke constructors of its parent class.

What are different types of inner classes?


There are four types of inner classes: member, static member, local, and anonymous.
  • A member class is defined at the top level of the class.
  • A static member class is defined like a member class, but with the keyword static.
  • A local inner class is defined within a method, and the usual scope rules apply to it.

Can inner class final?

There is no semantic difference between making a top-level class final and making an inner class final : it tells the compiler that you cannot inherit from the class. Marking classes final is sometimes done to let the compiler skip a virtual table lookup, but this is often regarded as premature micro-optimization.

What is static in Java?

In Java, a static member is a member of a class that isn't associated with an instance of a class. Instead, the member belongs to the class itself. As a result, you can access the static member without first creating a class instance. The value of a static field is the same across all instances of the class.

What is this in Java?

Keyword THIS is a reference variable in Java that refers to the current object. It can be used to refer instance variable of current class. It can be used to invoke or initiate current class constructor. It can be passed as an argument in the method call.

What is use of inner class in Java?


Java Inner Classes. Java inner class or nested class is a class which is declared inside the class or interface. We use inner classes to logically group classes and interfaces in one place so that it can be more readable and maintainable.

How do you call a class in Java?

The dot ( . ) is used to access the object's attributes and methods. To call a method in Java, write the method name followed by a set of parentheses (), followed by a semicolon ( ; ). A class must have a matching filename ( Car and Car.

What is wrapper class and number class?

All the wrapper classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class Number. The object of the wrapper class contains or wraps its respective primitive data type. Converting primitive data types into object is called boxing, and this is taken care by the compiler.