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Message:

Thanks for all your help, guys.

Posted by Steve on May 10, 2000 at 7:37 AM

> > > While trying to learn Java, I'm making flashcards until I get
> > > the basics down. I'd be grateful if you could review the Q/A's
> > > below and send any corrections to: yaeger2@gateway.net
> > > I'd also appreciate any new Q/A's for my flashcards or
> > > elaborations on Q/A's below. Thanks, Steve

> > >
> > > Q1 Explain the appearance of a constructor, when compared to a
> > > method.

> > > A1 A constructor looks like a method, but it lacks a return
> > > type.

> > In addition to that Constructor should have the same name as the class name.

> ***
> A constructor must have the same name as the class name without return type. If return type is specified, it will be a method ( like others methods).
> ***

> >
> > >
> > > Q2 Identify constructors and initializers in class CoffeeCup:
> > > class CoffeeCup {
> > > private int innerCoffee;
> > > //..
> > > }
> > > A2 There are none.

> > You are absolutely correct. JVM will create one default constructor for you. JVM will also initialize the variables which are not inside methods.

> ***
> JVM will create a constructor with no arguments.
> ***

> >
> > >
> > > Q3 Declare an uninitialized array of Point named myPoints.

> > > A3 Point myPoints[];

> > >
> > > Q4 In the code below, allocate an array of ten references to
> > > Point, called myPoints, that are initialized to the null
> > > reference:
> > > Point myPoints[];
> > >
> > > A4 myPoints = new Point[10]; (note: invalid??)

> ****
> Your answer is invalid, if it is in class scope. It is valid if that statement is in a method.

> You can't declare and initialize in two seperate statements in the class's scope.

> class MyClass {
> Point myPoints[] = new Point[10]; //This is valid
>
> myMethod {
> }
> }

> class MyClass {
> Point myPoints[];
> myPoints[] = new Point[10]; //This is invalid

> myMethod {
> }

> }

> class MyClass {
> Point myPoints[];
>
> myMethod {
> myPoints[] = new Point[10]; //This is valid
> }
> }

> ***

> > >
> > > Q5 Which string object is for read-only objects ?

> > > A5 The String class is for read-only objects.

> > >
> > > Q6 Which string object is for modifiable objects ?

> > > A6 The StringBuffer class is for objects that can be modified.

> > >
> > > Q7 String objects provide ? to obtain the number of characters
> > > in a string.

> > > A7 String objects provide the length() accessor method to obtain the number of characters in a string.

> > >
> > > Q8 A class definition has some or all of which six items ?

> > > A8 class variables, instance variables, class methods,
> > > instance methods, constructors, and static initializers

> > >
> > > Q9 What is a class ?

> > > A9 A class is a master copy of an object that determines what
> > > behavior and attributes the object should have.

> > >
> > > Q10 What's the format of a class called Dog ?

> > > A10 [keywords] class Dog [extends Superclass] [implements Interface] {
> > > // class body
> > > }

> > >
> > > Q11 What's a class variable ?

> > > A11 A class variable is associated with a class of objects,
> > > not just a single object.

> > >
> > > Q12 What is AWT ?

> > > A12 AWT stands for Abstract Windowing Toolkit; a set of Java
> > > classes that has been extended by the Swing windowing classes. They can be used to display and control a GUI.

> > >
> > > Q13 What is an argument ?

> > > A13 An argument is extra info that is either sent to a program
> > > at runtime (via the command prompt), or sent to a method during a program.

> > >
> > > Q14 What is an array ?

> > > A14 An array is a group of variables that share the same name
> > > and store the same kind of info.

> > >
> > > Q15 public Virus(String name, int size) {
> > > author = name;
> > > maxFileSize = size;
> > > }
> > > Write an example of code that could be used to call the above
> > > constructor.

> > > A15 Virus mumps = new Virus("Hall", 30000);
> > > or the format....
> > > Virus [reference] = new Virus("[string]", integer);

> > >
> > > Q15 public Virus(String name, int size) {
> > > author = name;
> > > maxFileSize = size;
> > > }
> > > The above constructor could be called only if ?

> > > A15 In the example code, the constructor could be called only
> > > if a string and an integer were sent as arguments, along
> > > with the new statement.

> ***
> String or integer 'compatible' arguments.
> ***

> > >
> > > Q16 In OOP, what's an attribute do ?

> > > A16 An attribute describes an object and distinguishes it from
> > > others.

> > >
> > > Q17 Where are attributes kept ?

> > > A17 Attributes are stored in variables.
>
>
> > Your answers are correct

> ***
> END
> ***

Thanks guys. I was doubtful about a few of them; it turns
out that I was just mixed up on a couple of things.

Steve