AP Computer Science A

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Object

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AP Computer Science A

Definition

An object is an instance of a class that represents a specific entity or thing in a program. It contains both data (attributes) and behavior (methods).

"Object" also found in:

Practice Questions (13)

What is the difference between a class and an object in Java?
What happens when a constructor changes the data of an object?
What is the default value of a reference variable that doesn't reference an object?
Consider the following class: ```java public class Rectangle { private int width; private int height; public Rectangle(int w, int h) { width = w; height = h; } // Getters and setters not shown for brevity } ``` What code should be added to the class so that a string representation in the format "Rectangle: width=xxx, height=yyy" can be obtained for an object of the class?
Given the block of code below, answer the following question: ```java class Person { // constructor not shown public void printGreeting() { System.out.println("Hello! How are you?"); } } class Student extends Person { // constructor not shown } ``` Question: Consider the code above. If we create an object of the `Student` class and call the `printGreeting()` method on that object, what will be outputted?
"Given the block of code below, answer the following question: ```java class Shape { // constructor not shown public void draw() { System.out.println("Drawing a shape"); } } class Circle extends Shape { // constructor not shown public void draw() { System.out.println("Drawing a circle"); super.draw(); } } ``` Question: Consider the code above. If we create an object of the Circle class and call the `draw()` method on that object, what will be the output?
Consider the code below. If we create an object of the B class and call the `printMessage()` method on that object, what will be the output? ```java class B { void printMessage() { super.printMessage(); System.out.println("Hello from B"); } } class A extends B { void printMessage() { System.out.println("Hello from A"); } } ```
Consider the code below. If we create an object of the Child class and call the `prinMessaget()` method on that object, what will be the output? ```java class Parent { void printMessage() { System.out.println("Hello from Parent"); } } class Child extends Parent { void printMessage() { super.printMessage(); System.out.println("Hello from Child"); } } ```
Consider the code below. If we create an object of the Child class and call the `printMessage()` method on that object, what will happen? ```java class Parent { void printMessage() { System.out.println("Hello from Parent"); } } class Child extends Parent { void printMessage() { printMessage(); System.out.println("Hello from Child"); } } ```
If you try to assign an object of a subclass to a reference variable of the superclass type, what will happen?
Given the block of code below, answer the following question: ```java class Animal { // constructor not shown } class Dog extends Animal { // constructor not shown public void makeSound() { System.out.println("Woof! Woof!"); } } ``` Question: Consider the code above. If we create an object of the `Dog` class and call the `makeSound()` method on that object, what will be outputted?
How would you create an object applePie based on a class called dessertRecipe?
What happens when an object is passed as a parameter to a method in Java?

Additional resources (3)

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Object

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AP Computer Science A

Definition

"Object" also found in:

Subjects (23)

Practice Questions (13)

Additional resources (3)

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that actually explain what's on your next test

Object

from class:

AP Computer Science A

Definition

Related terms

"Object" also found in:

Subjects (23)

Practice Questions (13)

Additional resources (3)

© 2024 Fiveable Inc. All rights reserved.

AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.

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