What is the use of inner classes in Java?
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.
How do you create 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. InnerClass innerObject = outerObject.
What are the rules for inner class in Java?
Rules of Local Inner Class:
- The scope of local inner class is restricted to the block they are defined in.
- Local inner class cannot be instantiated from outside the block where it is created in.
- Till JDK 7,Local inner class can access only final local variable of the enclosing block.
Can the modifiers public protected private and static be used for inner classes?
You can use the same modifiers for inner classes that you use for other members of the outer class. For example, you can use the access specifiers private , public , and protected to restrict access to inner classes, just as you use them to restrict access do to other class members.
Can Java inner class be private?
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.
What is the rule for local members in Java?
Rule for Local Variable Local variables cannot use any of the access level since their scope is only inside the method. Final is the Only Non Access Modifier that can be applied to a local variable. Local variables are not assigned a default value, hence they need to be initialized.
How many types of inner classes are there?
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.
Which is not a type of inner class?
Static nested classes are not technically an inner class. They are like a static member of outer class. Anonymous inner classes are declared without any name at all.