Mastering Java Concepts

What are the four types of inheritance in Java?

• Static Inheritance

• Single Inheritance, Multilevel Inheritance, Hierarchical Inheritance, Multiple Inheritance (via interfaces)

• Dynamic Inheritance

• Circular Inheritance

Explain the difference between an interface and an abstract class.

• An abstract class is a contract with no implementation, while an interface can have some implemented methods.

• An interface can have implemented methods, while an abstract class cannot.

• An interface is a contract with no implementation, while an abstract class can have some implemented methods and state.

• An interface can contain state, while an abstract class cannot.

Which method is used to compare two strings for equality in Java?

• isEqual()

• stringCompare()

• compareTo()

• equals()

What is the purpose of the 'throws' keyword in Java?

• To declare that a method can throw exceptions.

• To indicate a method's return type.

• To specify the method's access level.

• To define a method's parameters.

How do you create a custom exception in Java?

• public class MyCustomException extends Exception { public MyCustomException(String message) { super(message); } public MyCustomException(String message, Throwable cause) { super(message, cause); }}

• public class MyCustomException extends Exception { public MyCustomException(String message) { } }

• public class MyCustomException { public MyCustomException() { } }

• public class MyCustomException extends RuntimeException { }

What is single inheritance in Java?

• Single inheritance in Java allows a class to inherit from multiple superclasses.

• Single inheritance allows multiple classes to inherit from one superclass.

• Single inheritance in Java allows a class to inherit from one superclass only.

• Single inheritance means a class cannot inherit any properties from a superclass.

Can a class implement multiple interfaces? If yes, how?

• No, interfaces cannot be implemented by classes.

• Yes, a class can implement multiple interfaces.

• Yes, but only if the interfaces are related.

• No, a class can only implement one interface.

What method would you use to convert a string to an integer in Java?

• Integer.valueOfString()

• convertStringToInt()

• Integer.parseInt()

• String.toInteger()

What is the significance of the 'finally' block in exception handling?

• The 'finally' block can only be used with a try block that has no catch.

• The 'finally' block ensures that code runs after try/catch, regardless of exceptions.

• The 'finally' block is optional and does not affect program execution.

• The 'finally' block is used to catch exceptions before they propagate.

How do you handle multiple exceptions in a single catch block?

• Ignore exceptions and let them propagate.

• Use multiple catch blocks for each exception type.

• Use a single catch block with multiple exception types separated by a pipe (|).

• Only catch the most specific exception type.