CS 1331 Exam 2 Terms

A class is a "____"

What are the two main attributes of a class?

Values that are within the class but not within the methods; generally placed at the top of the class

Each object that gets instantiated for the class gets its own ____ of the instance variables

functions/procedures (behaviors) within the class

public double meth1(int var1, int var2) {
  double total;
  total = var1 * var2;
  return total;
}

//What is the content of the method referred to as?

control immediately goes back to call

What is the return statement for a void method?

Variables declared inside a method, and are only accessible in that method. In other words, the scope of these variables is the method in which they were created.

Variables passed into a method

Names of the parameters in the header declaration

Values passed in when running

(T/F) Arrays can be parameters

Methods that are not called in the context of an object.

Methods that are always called in the context of an object

A Java reserved word that is used inside methods. It refers to the object upon which the method was invoked.

A group of specified certain methods for outsiders to use

Modifiers that control access

Modifier that allows anyone to access instance data and methods

Modifier that only allows the class itself to access instance data and methods (i.e. objects of that class)

Modifier that allows a subclass to access instance data and methods from its super class, vice versa, and classes within the same package

A special method that is automatically called when objects are instantiated.

A constructor's primary use is to _______ instance variables.

The region of a program where variables are accessible.

The use of the same name with different paramater lists (types) to create multiple versions of a method

The part of a method declaration that includes the name, along with the paramater type and order.

Example:

meth1(int var1, int var2)

(T/F) A method signature includes the return type of that method

(T/F) Constructors can be overloaded

What is the proper syntax for a chained constructor call? (use 3 variables, denoting them as v1, v2, v3)

(T/F) A constructor must always have parameters as input

If a constructor for a class is not written, Java provides one for you when you create an object of that class. However, if you provide one with pamaraters, and you create an object with no paramaters, what happens?

A. The object is created with default values, and the code compiles.
B. The compiler will throw an exception.

int a; 

What is this an example of?

A. Declaration

B. Initialization

C. Instantiation

String s;  

What is this an example of?

A. Declaration

B. Initialization

C. Instantiation

int a;

 a = 0; //What does this line represent?

A. Declaration

B. Initialization

C. Instantiation

String s;

s = new String(“Hello”); //What does this line represent?

A. Declaration

B. Initialization

C. Instantiation

If we want to check whether two objects contain the same values, what method or operator do we use (hint: primarily used for objects)?

If we want to check whether two objects reference the same data, what method or operator do we use (hint: primarily used for primitive types)?

The method invoked when an attempt to print an object of that type occurs

A modifier that creates one copy of a variable or method that is shared by all instances of the class

Where is the memory space for static variables located?

(T/F) Static methods can reference instance variables

A reserved word for objects that have no reference; can occur after declaration but no instantiation

A special type of constructor that takes in an object of that class and "copies" its contents. When called, an object with the same values as the paramater object will be created.

A class that corresponds to a primitive type. Allows the usage of primitive types as objects. i.e. Integer, Double, etc.

(T/F) Java will automatically convert between primitive and Wrapper when needed

Converting a wrapper to a primitive type

Converting a primitive type to a Wrapper

Documenting your code

The process of deriving a new class from an existing one. Automatically contains some or all of the methods of the original. Can add new ones to it.

A keyword that denotes that a class is a subclass of a super class; placed in class header

What type of hierarchy represents the super-sub class relationship?

keyword for denoting access to parent's members

What is the proper syntax for calling the constructor of the parent class from the child class? Use "v1" as the variable.

(T/F) When using the super() call in the constructor of the child class, this line of code can appear anyhwere within the body of the constructor.

(T/F) If the first line of a sub-class constructor is not an explicit call to a super class constructor, Java inserts super() automatically.

When a child class defines a method with the same name (and signature) as the parent, child's version overrides the parent's version

What is the correct syntax for notifying the compiler of a method override for a child class?

(T/F) Static methods can be inherited and overridden

Java has _____ inheritance; it can extend at most one class

The class that all classes are ultimately derived from. Contains methods such as equals(), toString(), clone().

keyword that checks if an object is an instance of another class

Method that returns the class an object is an instance of

chained constructor call (use xxxx as param, variable, or method name)

Instance data of object that is being called upon.
(use xxxx as param, variable, or method name)

Calling a method within the class, do not necessarily need "this"
(use xxxx as param, variable, or method name)

calling super class constructor
(use xxxx as param, variable, or method name)

Accessing instance variable from super class. (use xxxx as param, variable, or method name)

a “placeholder;” useful for super and sub classes in which the super class contains a abstract method that must be included in the subclasses.

(T/F) Abstract classes cannot contain non-abstract methods

(T/F) In order for an abstract method to exist, the subclasses must either override the method or be absract themselves.

Abstract methods (can/can’t) have concrete constructors.

(T/F) You can instantiate an abstract class with new()

A keyword that is used to denote that a class cannot be extended, the value of a variable cannot be changed, or that a method cannot be overridden.

A variable’s type at compile time; what class the object is declared as

Suppose a Person class with a constructor and methods is created. Also suppose that a subclass named Student is created and extends Person. Now, suppose we create a Person object p and write the following lines of code.

Person p;

p = new Student(“Mary”, 1);

//What is the static type of p?

the type of object a variable references at run-time; the class an object is instantiated as.

Suppose a Person class with a constructor and methods is created. Also suppose that a subclass named Dentist is created and extends Person. Now, suppose we create a person object p and write the following lines of code (assume “xxxx” are paramaters).

Person p;

p = new Dentist(xxxx);

//What is the dynamic type of p?

(T/F): If you do not write a toString() method for a class and attempt to print an object that is an instance of that class, you will get a compiler error.

Write the method declaration of an abstract void method that takes no parameters, is public, and is named “method1”.