What is inner class in Java explain with example?

Java inner class or nested class is a class that is declared inside the class or interface. We use inner classes to logically group classes and interfaces in one place to be more readable and maintainable. Additionally, it can access all the members of the outer class, including private data members and methods.

What is an inner class and example in Java?

Unlike a class, an inner class can be private and once you declare an inner class private, it cannot be accessed from an object outside the class. Following is the program to create an inner class and access it. In the given example, we make the inner class private and access the class through a method.

How do you define an inner class?

In object-oriented programming (OOP), an inner class or nested class is a class declared entirely within the body of another class or interface. It is distinguished from a subclass.

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What are the types of inner classes in Java?

There are 4 types of inner classes in Java:

  • Nested Inner class.
  • Method local inner classes.
  • Anonymous inner classes.
  • Static nested classes.

Why do we need inner class in Java?

Inner classes are a security mechanism in Java. We know a class cannot be associated with the access modifier private, but if we have the class as a member of other class, then the inner class can be made private. And this is also used to access the private members of a class.

What is the inner class file name?

The class file name of inner class is “Outer$Inner”. $ symbol is used to represent inner classes.

How do you write an inner class in Java?

To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax: OuterClass outerObject = new OuterClass(); OuterClass. InnerClass innerObject = outerObject.

What is an inner class give examples of various 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. It may have the same access modifiers as variables (public, protected, package, static, final), and is accessed in much the same way as variables of that class.

What is local inner class in Java?

Local Inner Classes are the inner classes that are defined inside a block. Generally, this block is a method body. Sometimes this block can be a for loop or an if clause. Local Inner classes are not a member of any enclosing classes. … Local inner class must be instantiated in the block they are defined in.

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What is the difference between an inner class and a sub class?

inner classes are in the same file, whereas subclasses can be in another file, maybe in another package. You cannot get an instance of an inner class without an instance of the class that contains it. inner classes have the methods they want, whereas subclasses have the methods of their parent class.

How many inner classes can a class have?

Probably you can’t have a . java file 4gb big, so extrapolating from that number you can say that there are probably less than some hundred million classes that can be inner classes of a class. It’s 14 characters. Now, 4gb / 14 characters = 300 million inner classes.

Can inner class have main method?

main method in inner classes

Inside inner class we can’t declare static members. So that it is not possible to declare main() method inside non static inner class.

Which is not a type of inner class?

Static nested classes are not technically inner classes. They are like a static member of outer class. Example: Java.

Why should we use inner class?

Inner classes are used to get functionality which can get an object better than method. They can be used in the case when a set of multiple operations are required and chances of reusability are good inside the class and they will not be accessed but methods outside the outer class.

Can inner class object be synchronized?

There is no special relation between the synchronized methods of an inner class and the enclosing instance. To synchronize on an enclosing instance, use an explicit synchronized statement. It is a common mistake to try to use the loop index directly within the inner class body.

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What is the difference between nested class and inner class in Java?

In Java programming, nested and inner classes often go hand in hand. A class that is defined within another class is called a nested class. An inner class, on the other hand, is a non-static type, a particular specimen of a nested class.

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