Abstraction and Program Design - AP Computer Science A

The result is 3, due to integer division. Both operands are integers, so result truncates decimal portion.

Java does not support multiple inheritance of classes. Classes can only extend one superclass in Java.

public static void main(String[] args). Entry point for Java applications, must match exact format.

Interfaces cannot have method bodies. Only default and static methods can have implementations.

Use 'int x;' or 'Integer x = new Integer();'. Primitives cannot use constructor syntax, only reference types.

No error; the syntax is correct. Static variables are properly declared at class level.

Duplicate parameter name 'a'. Parameter names must be unique within method signature.

Method overriding is an example of polymorphism. Subclass methods can replace superclass method behavior.

The 'abstract' keyword is used to declare an abstract class. Marks class as incomplete, requiring subclass implementation.

The default access modifier is package-private. Accessible within package but not from outside packages.

Inheritance promotes code reuse. Avoids duplicating code across multiple related classes.

The 'implements' keyword is used to implement an interface. Creates contractual obligation to provide method implementations.

The 'extends' keyword is used to inherit a class. Establishes is-a relationship between parent and child classes.

Encapsulation protects an object's internal state from unintended modification. Private fields prevent direct external manipulation of data.

Abstraction can be achieved using abstract classes and interfaces. Both provide contracts without revealing implementation details.

'protected' allows access within the same package and subclasses. Package access plus inheritance-based access for subclasses.

'private' restricts access to the class itself. Most restrictive access, only within declaring class.

'public' makes a class, method, or field accessible from any other class. Broadest access level, no restrictions on usage.

'final' is used to declare constants, prevent inheritance, and prevent method overriding. Prevents modification, inheritance, or method overriding.

'this' is used to refer to the current object instance. Distinguishes between instance variables and parameters with same names.

A static method belongs to the class rather than any object instance. Called on class itself, not requiring object instantiation.

A concrete class is a class that has no abstract methods. Can be instantiated directly, no abstract methods present.

Abstraction reduces complexity and increases efficiency. Simplifies development by hiding unnecessary implementation details.

A constructor is a special method to initialize objects. Called automatically when creating new object instances.

Polymorphism allows for methods to do different things based on the object it is acting upon. Enables same method name to behave differently across classes.

A subclass is a class that inherits from another class, the superclass. Also called child class, extends functionality of parent class.

A superclass is the class from which a subclass inherits. Also called parent class, provides structure for child classes.

Inheritance allows a class to inherit fields and methods from another class. Enables code reuse by establishing parent-child class relationships.

Encapsulation is bundling data with methods that operate on it. Key principle protecting data integrity through controlled access.