Java Language and Object Oriented Programming Concepts Questions and Answers 100% Pass

Java Language and Object Oriented Programming Concepts Questions and Answers 100% Pass What happens when an exception occurs in a constructor? Object creation fails, and the exception must be handled. Can an interface have static methods? Yes, since Java 8, interfaces can have static methods. What is a functional interface? An interface with exactly one abstract method, used for lambda expressions. Why are wrapper classes used in Java? To allow primitive values to be used as objects. Can a method be both `synchronized` and `final`? Yes, a method can be both synchronized and final. 2 Why is Java not 100% object-oriented? Because it supports primitive data types. How do you stop object creation in Java? By making the constructor private. What is constructor chaining? Calling one constructor from another within the same class or between parent and child classes. Can a `static` variable be `final`? Yes, a `static final` variable is a constant. What is the difference between `deep copy` and `shallow copy`? A shallow copy copies references, while a deep copy creates independent copies of objects. Can we call `super()` multiple times in a constructor? No, `super()` must be the first statement and can be called only once. 3 What is a transient variable? A variable that is not serialized. Can you synchronize a constructor? No, but you can use a synchronized block inside it. Why is Java’s `String` class immutable? To improve security, caching, and performance in string handling. What is encapsulation in Java? Encapsulation is the practice of wrapping data and methods into a single unit while restricting direct access to certain details. Can an abstract class have a constructor? Yes, an abstract class can have a constructor, and it is called when a subclass is instantiated. What happens if you do not override `hashCode()` when overriding `equals()`? 4 Objects that are considered equal may have different hash codes, leading to unexpected behavior in hash-based collections. How can you create a deep copy of an object in Java? By implementing `Cloneable` and overriding `clone()`, or by using serialization and deserialization. Can a private method be overridden? No, private methods are not inherited and cannot be overridden in a subclass. What is the difference between method overloading and method overriding? Overloading happens in the same class with different parameters, while overriding happens in a subclass with the same method