Programming Week 10 Flashcards

Array Access

• Use System.out.println(ar[ar.length - 1]); to print the last element of the array ar.
• Accessing ar[ar.length] is out of bounds and will result in an error.

Method Behavior

• Method signature void m(int[] ar) can change values in the array ar directly since arrays are reference types.

Array Properties

• vals.length for the 2D array vals is 4, indicating the number of arrays it contains.

Data Types

• The data type of num in int[] num = new int; is int, indicating an integer array.

Constructors

• Constructors share the same name as the class they belong to.
• A class can have any number of constructors, allowing for different ways to instantiate objects.

Accessor Methods

• Accessor instance methods typically begin with "get" for returning values or "is" depending on the return type.

Class Instantiation

• To instantiate a Rectangle object, the correct syntax is Rectangle myRectangle = new Rectangle(10, 12);.

Default Constructor

• A valid default constructor for Clock is public Clock() { setTime(0, 0, 0); }.

Public Methods

• The method setTime(int, int, int) is public and does not return anything.

Valid Method Calls

• The valid set of statements to call methods on a Rectangle object is:
  • bigRect.area();
  • bigRect.perimeter();
  • bigRect.print();

Class Relationships

• The "is-A" relationship occurs when a subclass is a type of its superclass, indicating a hierarchy.

Inheritance

• Inheritance allows for the expression of relationships between classes, promoting code reuse.

Method Overloading

• When overloading a method in a subclass, you must change the number, type, or order of parameters.

Constructor Requirement

• When defining a subclass without a constructor, its superclass must either have no constructors defined or have a default (no-arg) constructor.

UML Diagrams

• The method toString() serves to provide a string representation of the object.

Superclass Constructors

• A subclass constructor with Student(String name, long id) will compile if the superclass Person has a default or no-arg constructor.

Object Reference Output

• The method used to print an object in the format pete is Person@addbf1 is toString().

ArrayList Requirement

• To use ArrayList, import the class from the java.util package.