Question-111. What do you mean by Checked Exceptions ?
Answer- It is an exception that is typically a user error or a problem that cannot be foreseen by the programmer. For example, if a file is to be opened, but the file cannot be found, an exception occurs. These exceptions cannot simply be ignored at the time of compilation.
Question-112. Explain Runtime Exceptions ?
Answer- It is an exception that occurs that probably could have been avoided by the programmer. As opposed to checked exceptions, runtime exceptions are ignored at the time of compliation.
Question-113. When super keyword is used ?
Answer- If the method overrides one of its superclass’s methods, overridden method can be invoked through the use of the keyword super. It can be also used to refer to a hidden field.
Question-114. What is Polymorphism ?
Answer- Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.
Question-115. What is abstraction ?
Answer- It refers to the ability to make a class abstract in OOP. It helps to reduce the complexity and also improves the maintainability of the system.
Question-116. What is encapsulation? ?
Answer- It is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. Therefore encapsulation is also referred to as data hiding.
Question-117. What is Abstract class ?
Answer- These classes cannot be instantiated and are either partially implemented or not at all implemented. This class contains one or more abstract methods which are simply method declarations without a body.
Question-118. When Abstract methods are used ?
Answer- If you want a class to contain a particular method but you want the actual implementation of that method to be determined by child classes, you can declare the method in the parent class as abstract.
Question-119. What is an Interface ?
Answer- An interface is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface.
Question-120. What do you mean by Multithreaded Program ?
Answer- A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution.