All Flashcards
What are the differences between primitive types and reference types?
Primitive types store values directly; reference types store memory addresses. Primitive types start with lowercase; reference types start with uppercase.
What is the difference between == and .equals() when comparing objects?
== compares memory addresses (references); .equals() compares the content of the objects (if properly implemented).
Compare the use of the String class with the Math class.
String is used to create and manipulate text; Math provides static methods for mathematical operations. String objects are created with new or string literals; Math cannot be instantiated.
What is the difference between a static method and an instance method?
A static method belongs to the class itself and is called using the class name; an instance method belongs to an object of the class and is called using the object's name.
Compare Abstraction and Encapsulation.
Abstraction focuses on hiding complexity and showing only essential features, while encapsulation focuses on bundling data and methods that operate on that data, protecting it from outside access.
Compare Inheritance and Polymorphism.
Inheritance allows a class to inherit properties and behaviors from another class, promoting code reuse, while polymorphism allows objects of different classes to be treated as objects of a common type, enabling flexibility and extensibility.
How are objects used to represent real-world entities?
Objects can model real-world entities by encapsulating their attributes (data) and behaviors (methods). For example, a 'Car' object can have attributes like color and speed, and methods like accelerate and brake.
How is the Math class applied in real-world scenarios?
The Math class is used in scientific calculations, simulations, game development, and financial modeling.
How is the String class used in real-world applications?
The String class is used for text processing, data validation, user input handling, and storing textual information in applications.
How are objects used in creating user interfaces?
UI elements like buttons, text fields, and windows are often represented as objects with specific properties and behaviors.
How are objects used in game development?
Game characters, items, and environments are typically represented as objects with attributes and methods that define their behavior and interactions.
How is the concept of objects helpful in managing data?
Objects allow you to group related data and functions together, making it easier to organize, access, and manipulate complex data structures.
What is the role of a class in object creation?
A class serves as a blueprint, defining the structure and behavior of objects.
What does the new keyword do?
It's used to create a new object (instance) of a class, calling the constructor.
Explain the difference between a class and an object.
A class is a blueprint, while an object is a specific instance of that blueprint.
What is the significance of objects being reference types?
Objects store memory locations rather than actual values, affecting how they are handled in memory and during assignment.
What is the purpose of a constructor?
To initialize the state of an object when it is created.
What are the key principles of OOP?
Abstraction, Encapsulation, Inheritance, and Polymorphism.
What is the role of methods in a class?
Methods define the behaviors or actions that an object can perform.
Why is understanding objects important in Java?
Because Java is an object-oriented language, and objects are fundamental building blocks.
What does it mean for an object to be an instance of a class?
It means the object is a specific realization or example created from the class's blueprint.
What happens when you assign one object to another?
You are copying the reference (memory address), not creating a new, independent object.