Lesson 20 Excercise

Lesson 20 Exercise

Matthew Walker

Balcar 3A 1/30/13

1. At any time after several TvShow objects have been instantiated, how would you find out

how many shows were instantiated? (Don’t use an object to do this.)

2. Would the code inside the numberOfShows method still be correct if numberOfShows

were non-static? If not, why?

3. Suppose the code inside the numberOfShows method is replaced with the following line:

return y;

Is this legal? If not, why?

4. Write code that will print the data member actor2. Do this without instantiating any

objects.

5. Is the following code legal? If not, why?

TvShow.setActor1(“Jimmy Stewart”);

6. Create an instance of TvShow called chrs (pass in the String “Cheers”) and use it to

access and print the class variable numShows.

7. Give the output of the following:

System.out.println(TvShow.x);

TvShow chrs = new TvShow(“Cheers”);

System.out.println(TvShow.x);

System.out.println(chrs.x);

TvShow hc = new TvShow(“History Channel”);

hc.x = 160;

System.out.println(TvShow.x);

System.out.println(hc.x);

8. Is the following a legal declaration of a class variable? If not, why?

static public char ch = ‘K’;

9. Write code that will cause the variable zxb to be a static state variable. The variable zxb is

a double.

10. Write code that will cause sn to be a constant static class member. The constant sn should

be initialized as an empty String.

11. What is the significance of the word Math when we use Math.pow(3.2, 4.001)?

Math is the class variable

12. Class variables are also called Static State variables.

13. Assuming that the appropriate static import has been done, rewrite the following code

without using the class name of the static methods.

double xop = Math.pow(Math.sqrt(x - zv), 3.1);

14. What are the two primary reasons for using the key-word, static?

            1. you can call a method without creating an object

2. they are shared by all objects