Java Concepts Assessment

What is a control statement in Java?

• A control statement in Java is a statement that controls the flow of execution based on conditions.

• A control statement in Java is a method for defining classes.

• A control statement in Java is a type of data structure.

• A control statement in Java is used to declare variables.

Explain the difference between '==' and 'equals()' in Java.

• '==' checks value equality, while 'equals()' checks reference equality.

• '==' is used for primitive types, while 'equals()' is for objects only.

• Both '==' and 'equals()' check reference equality.

• '==' checks reference equality, while 'equals()' checks value equality.

What is inheritance in Java? Provide an example.

• A subclass cannot access any properties of its superclass.

• For example, if we have a superclass 'Animal' and a subclass 'Dog', the 'Dog' class can inherit properties like 'name' and methods like 'eat()' from the 'Animal' class.

• Inheritance allows classes to be created without any parent class.

• Inheritance in Java is only applicable to interfaces.

Define polymorphism and its types in Java.

• There are two types of polymorphism in Java: 1) Compile-time polymorphism (method overloading) and 2) Runtime polymorphism (method overriding).

• Polymorphism refers to the ability to change the data type of a variable at runtime.

• There is only one type of polymorphism in Java: method overriding.

• Polymorphism is the ability to create multiple classes in Java.

What is an abstract class? How is it different from an interface?

• An abstract class is a type of interface that can be instantiated.

• An abstract class cannot be instantiated and can have both abstract and concrete methods, while an interface defines a contract with only abstract methods.

• An interface can have both abstract and concrete methods, while an abstract class cannot.

• An abstract class can be instantiated and has only abstract methods.

How do you implement method overriding in Java?

• Implement the method in a separate utility class.

• Use the @Override annotation in the superclass method.

• To implement method overriding in Java, define a method in the subclass with the same name and parameters as in the superclass, and use the @Override annotation.

• Define a method in the superclass with a different name.

What are the different types of operators in Java?

• Bitwise, Assignment, Modular

• Relational, Conditional, Unary

• Arithmetic, Relational, Logical, Bitwise, Assignment, Unary, Ternary

• Arithmetic, Geometric, Logical

Explain the use of the 'break' statement in loops.

• The 'break' statement pauses the loop for a specified duration.

• The 'break' statement exits a loop when a specified condition is met.

• The 'break' statement is used to skip the current iteration of the loop.

• The 'break' statement continues to the next iteration of the loop.

What is the purpose of the 'super' keyword in inheritance?

• To define a new method in the child class.

• To override a method in the child class.

• To access methods and properties of a parent class.

• To create a new instance of a class.

How can you achieve method overloading in Java?

• Use inheritance to create a new method with a different name.

• Override existing methods to change their behavior.

• Define multiple methods with the same name but different parameter lists.

• Define multiple methods with the same name and same parameter types.