Java

TOPIC 46 – OBJECT ARRAYS

LESSON WORK

QUESTION #3 – LOTSA CLOWNS (SELF-CHECK)

SOLUTIONS

Copy the code from this Clown class to your project. Examine the Clown class to get an understanding of it. Below are a few questions to help you examine the Clown class.

PART A – OOP REVIEW

A) How many instance variables does the class have?

It has three instance variables: height, behavior and shoes.

B) Are the instance variables accessible from other classes?

No they are not because they are all private.

C) Once a Clown instance is created, is it possible to change any of the instance variables?

It is not possible change the height and shoes instance variables. However, one can change the behaviour instance variable by using the makeAngry() method.

D) What line of code is required to create an instance of Clown named bozo?

Clown bozo = new Clown();

E) What line of code is needed to output a String representation of the Clown object to screen? Try it.

System.out.println(bozo);

PART B – ARRAYS

F) Write the statement(s) that create(s) a Clown array that contains 8 clowns. Make sure the Clown objects are created as well.

Option #1:

Clown[] circus = new Clown[8];

circus[0] = new Clown();

circus[1] = new Clown();

circus[2] = new Clown();

circus[3] = new Clown();

circus[4] = new Clown();

circus[5] = new Clown();

circus[6] = new Clown();

circus[7] = new Clown();

Option #2:

Clown[] circus = new Clown[8];

for(int i=0; i<circus.length; i++)

{

circus[i] = new Clown();

}

Option #3: (Should all be on one line of code)

Clown[] circus = {new Clown(), new Clown(), new Clown(), new Clown(), new Clown(), new Clown(), new Clown(), new Clown()};

G) Use a for loop to output the String representation of each Clown instance in the array one at a time.

for (int i=0; i<circus.length; i++)

{

System.out.println(circus[i]);

}

The above code will output something like this:

A tall silly clown with big blue shoes.

A short cranky clown with big blue shoes.

A short silly clown with sparkly purple shoes.

A short silly clown with floppy red shoes.

A short giggly clown with big blue shoes.

A tall happy clown with sparkly purple shoes.

A tall cranky clown with sparkly purple shoes.

A tall silly clown with floppy red shoes.

H) Use another for loop to make all Clown instances angry. Then, in yet another for loop, output String representations of each Clown once again to make sure they truly are angry clowns.

for (int i=0; i<circus.length; i++)

{

circus[i].makeAngry();

}

for (int i=0; i<circus.length; i++)

{

System.out.println(circus[i]);

}