Home Interview Questions and Answers Java Interview Questions and Answers For Graduates Part-4

java31.What is an Exception?
An exception is a problem that arises during the execution of a program. Exceptions are caught by handlers positioned along the thread’s method invocation stack.

32.What do you mean by Checked Exceptions?
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.

33.Explain Runtime Exceptions?
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.

34.Which are the two subclasses under Exception class?
The Exception class has two main subclasses : IOException class and RuntimeException Class.

35.When throws keyword is used?
If a method does not handle a checked exception, the method must declare it using the throwskeyword. The throws keyword appears at the end of a method’s signature.

36.When throw keyword is used?
An exception can be thrown, either a newly instantiated one or an exception that you just caught, by using throw keyword.

37.How finally used under Exception Handling?
The finally keyword is used to create a block of code that follows a try block. A finally block of code always executes, whether or not an exception has occurred.

38.What things should be kept in mind while creating your own exceptions in Java?
While creating your own exception −

All exceptions must be a child of Throwable.

If you want to write a checked exception that is automatically enforced by the Handle or Declare Rule, you need to extend the Exception class.

You want to write a runtime exception, you need to extend the RuntimeException class.

39.Define Inheritance?
It is the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.

40.When super keyword is used?
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.

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