Greenfoot Ch 1-4 (Version 2)

In object-oriented programming a method is

• A design technique for creating classes

• A disciplined way of writing programs

• An approach developed by the great Stanislawski

• A process for instantiating an object

• Code that allows access to an object's attributes or that carries out some other action for the object.

The return type of a method

• Specifies the number of items a method returns

• Specifies what a method call will return

• Specifies the type of data that a method will accept.

• Is always void

To pass additional data to a method we specify a

• Name

• Return type

• Parameter

• Parenthesis

When a method returns nothing this special word is used for the return type:

Changing the flow of control in a program to jump to some pre-written code is known as ___________________ a method.

The code that a programmer writes is called _______________ code.

A compiler

• Maintains a collection of programs

• Tests a program's logic

• Translates source code into executable code

• Translates executable code to machine code

Given an integer variable  drivingAge that has already been declared, write a statement that assigns the value  17 to  drivingAge . So, after your code is executed, the variable drivingAge, will have the value  17.

This kind of comment tag is used for what kind of comments? //

• Group

• Single line

_________: - Translate source code into byte code which the Java Interpreter (JVM- Java Virtual Machine) can understand.

The ".class file" contains this kind of code.

A class name is written in this format

A method is written in this format.

Readable, English like code that is written by a programmer in a particular programming language and is saved in the ".java" file.

_____________ classes have subclasses.  Choose the best answer.

• Crab

• Super

• Actor

• World

How would you call or invoke the following method? public void move()   {       setLocation(getX() + 5, getY();   }

• Public void move();

• Move()

• Move();

Call the turn method from the given method. public void turn (int angle) {        setRotation(getRotation() + angle);  }

• Turn(45);

• Public void turn (45);

• Turn(45)

• Public void turn (45)

An example of this kind of error would be missing ( )  on a method.

This kind of error compiles but the data that comes out is wrong.  For example, you want your balloons to move up but they go to the right.

This kind of comment tag is used for what kind of comments? /* */

• Single line

• Group

How does Step differ from Step into?

• Step steps over methods, Step Into steps into methods

• Step steps into methods, Step Into steps over methods

Reasons for using comment tags

• Describe your code so other programmers can follow it

• Help document your code so you can follow it

• Trouble shoot your code by commenting out sections of code

The general "if statement"  format it is if ( _______________ ) {     statements to execute }

• Boolean statement

• Condition

• Statements

When an object has an "is a" relationship with another object, that relationship is called ____________

You cannot right click on the Animal Class in our Crab world scenario and create an object.  What kind of class is the Animal class?

What is the formal name for the process of creating an object from a class?

Calling this kind of method is like a command.

• Int

• Boolean

• Void

A boolean return data type gives us a true false return.

• True

• False

How many parameters does this method have? compare (int x, int y, int z)

Public void move()  - This part of the method is called the ________________________. { }

It is good naming convention to  name a class in Greenfoot “crab” .

• True

• False

Single line comment tags are written with ____

Which are correct ways to indicate 25%

• GetRandomNumber(100) < 25

• GetRandomNumber(4) < 1

• GetRandomNumber(16) < 4

Strings are indicated with double quotes.

• False

• True

Using a dot between a class name and a method name is called ____ ____.

What class is this method from? static int getRandomNumber(int limit)

Write a method call that will return a random integer between 0 and 10.                                         

• Greenfoot.getRandomNumber(10)< 1;

• Greenfoot.getRandomNumber(100) < 10;

• Greenfoot.getRandomNumber(10);

• Greenfoot.getRandomNumber(10)+1;

  Methods that belong to classes (as opposed to objects) are marked with the keyword static in their signature.

• True

• False

How would I write a random number that would show numbers from 1 to 8?

• Greenfoot.getRandomNumber(8) + 1;

• Greenfoot.getRandomNumber(8);

• Greenfoot.getRandomNumber(1) + 8;

Write an if statement that tells an object to turn  17 degrees,  but only 31 percent of the time.

• If (Greenfoot.getRandomNumber(100) <31); turn(17);

• If (Greenfoot.getRandomNumber(100) <31) turn(17);

• If Greenfoot.getRandomNumber(100) <31 turn(17);

This statement  tells an object to turn a random number of degrees between -20 and 20.        Greenfoot.getRandomNumber(-20, 20);

• True

• False

Given the following constructor, what is the correct way to add an elephant object from this constructor at coordinates, 50,50? public Elephant()     {         imageDown = new GreenfootImage("elephant.png");         imageUp = new GreenfootImage("elephant2.png");         setImage(imageDown);     }

• Elephant();

• New Elephant()

• This is an invalid constructor.

• AddObject(new Elephant(), 50,50)

This is a valid constructor public  void AnimalWorld()     {            // Create a new world with 400x300 cells         // with a cell size of 1x1 pixels.         super(400, 300, 1);     }

• True

• False

Common characteristics of a constructor’s signature

• Same name as the class

• No return type

• Public modifier

This is a valid constructor public Elephant()     {         imageDown = new GreenfootImage("elephant.png");         imageUp = new GreenfootImage("elephant2.png");         setImage(imageDown);     }

• True

• False

A constructor must be called to create an object

• True

• False

An instance variable is sometimes called a ________

You may not be accessed directly by any code outside the class (can’t get to it with the ‘.’)  and is not inherited by subclasses.

• Private

• Protected

• Public