Oracle Interview Questions and Answers

The four pillars of OOP are encapsulation, inheritance, polymorphism, and abstraction. Arrays are fixed-size data structures, while vectors are dynamic arrays. A queue can be implemented using two stacks.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Creating new classes based on existing classes, inheriting their attributes and methods.

• Polymorphism: Objects of different classes can be treated as objects of a common superclas...read more

Abstract class is a class with abstract methods, interface is a contract with only abstract methods. Array is fixed size, ArrayList is dynamic. Method overloading is same method with different parameters, overriding is redefining a method. OOP pillars are inheritance, encapsulation, polymorphism, abstraction. Deadlock is a situation where two or more processes are unable to proceed because each is waiting for the other to release a resource. Normalization is the process of or...read more

Object is an instance of a class with its own state and behavior, while constructor is a special method used to initialize objects.

• Object is created from a class using the 'new' keyword.

• Constructor is a special method with the same name as the class.

• Object has its own state (attributes) and behavior (methods).

• Constructor is used to initialize the state of an object when it is created.

• Example: Class Car { constructor(make, model) { this.make = make; this.model = model; } }

• Exam...read more

Abstraction focuses on hiding the implementation details while encapsulation focuses on bundling the data and methods that operate on the data into a single unit.

• Abstraction is the concept of hiding the complex implementation details and showing only the necessary features of an object.

• Encapsulation is the bundling of data and methods that operate on the data into a single unit.

• Abstraction allows for creating simple interfaces for complex systems, while encapsulation helps in...read more

DBMS stands for Database Management System. It is a software system that allows users to define, create, maintain and control access to databases.

• DBMS is a software system that manages databases.

• It allows users to define, create, maintain, and control access to databases.

• DBMS provides tools for data manipulation, retrieval, and security.

• Examples of DBMS include MySQL, Oracle, SQL Server, and PostgreSQL.

String builder is faster but not thread-safe, while string buffer is slower but thread-safe.

• String builder is recommended for single-threaded applications for better performance.

• String buffer is recommended for multi-threaded applications to ensure thread safety.

• Example: StringBuilder sb = new StringBuilder(); StringBuffer sbf = new StringBuffer();

The four pillars of object-oriented programming are encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a new class to inherit properties and behavior from an existing class.

• Polymorphism: The ability for objects of different classes to respond to the same message.

• Abstraction: Hiding the complex implementation details and showing only the necessary features of an ob...read more

The final keyword in OOP is used to restrict the user from changing the value of a variable, overriding a method, or inheriting from a class.

• Final variable: value cannot be changed once assigned

• Final method: cannot be overridden in child classes

• Final class: cannot be inherited by other classes