Java Unit 4 Assignment

This is the class needed for questions 1-11.

import java.awt.geom.Rectangle2D;

public class MyRectangleContainer
{
private Rectangle2D.Double containedRectangle; private String nameOfRectangle;

public MyRectangleContainer() { containedRectangle = null; }

public MyRectangleContainer(Rectangle2D.Double rectanglein, String namein) { containedRectangle = rectanglein; nameOfRectangle = namein; }

public void setName(String namein) { nameOfRectangle = namein; }

public void setRectangle(Rectangle2D.Double rectanglein) { containedRectangle = rectanglein; }

public String getName() { return nameOfRectangle; }

public Rectangle2D.Double getRectangle() { return containedRectangle; }
}
This is the beginning of the program needed for questions 1-11.

import java.awt.geom.Rectangle2D;

public class Assignment4RectangleProg
{
public static void main(String[] args) { MyTerminalIO myterminal = new MyTerminalIO();

int x, y, w, h;

myterminal.print("Enter an x value: "); x = myterminal.getInt(); myterminal.print("Enter a y value: "); y = myterminal.getInt(); myterminal.print("Enter a w value: "); w = myterminal.getInt(); myterminal.print("Enter an h value: "); h = myterminal.getInt();

/* Your code would go here. */ }
}

The first 11 questions refer to the code for the MyRectangleContainer class, which is given on the previous page. Questions 1-8 ask you to write lines of code which would follow in a program, the beginning of which is given above. The 8 questions are shown below as they might appear on a test, but without enough room for a handwritten answer. For the assignment the questions are design specifications for work you will do on the computer. What you need to do is hand in a working program that follows these specifications. Compile and debug the program and then run it. Hand in a copy of your finished code and a printout of the output of a test run of the program.

Remember how to make a program and a class work together. You have two choices: 1. Save the MyRectangleContainer class in a file by itself. Also save your program, Assignment4RectangleProg, in a file by itself. Use the usual naming conventions and make sure they’re together in the same directory. 2. It is also possible to put these two pieces of code together in a single file if you want to. Put your program first and the class second in the file. Save the file under the program name, not the class name. Make sure that you change the line of code that declares the class so that it no longer has the key word public in it.

1. Declare and construct an instance of the Rectangle2D.Double class called myrectangle. Use the parameter values already taken in in the program code provided.

2. Write a prompt that will ask the user to enter a name for a Rectangle2D.Double.

3. Take in the the name of the Rectangle2D.Double and store it in myname.

4. Declare and construct an instance of the MyRectangleContainer class using the values myrectangle and myname. Call this instance mycontainer.

5. Write a line of code that would change the nameOfRectangle value stored in mycontainer to Betty Boop.

6. Write a line of code that would change the containedRectangle value stored in mycontainer to the null reference.

7. Write a line of code that would declare a variable called retrievedName and store in it the current value of nameOfRectangle in mycontainer.

8. Write a line of code that would declare a variable called retrievedRectangle and store in it the current value of containedRectangle in mycontainer.

For questions 9 and 10, suppose a program using the MyRectangleContainer class contained the following line of code. Suppose also that no other lines of code do anything with samplecontainer before the questions below.

MyRectangleContainer samplecontainer = new MyRectangleContainer();

9. You don’t have to write down the exact output, but accurately describe the effect or output of executing the following code if it came after the code shown above. Write your answer in the space provided.

Rectangle samplerect = samplecontainer.getRectangle(); myterminal.println(samplerect); 10. You don’t have to write down the exact output, but accurately describe the effect or output of executing the following code if it came after the code shown above. Write your answer in the space provided.

String samplename = samplecontainer.getName(); myterminal.println(samplename); 11. This question is independent of 9 and 10. You don’t have to write down the exact output, but accurately describe the effect or output of executing the following code.

MyRectangleContainer sampletwo; myterminal.println(sampletwo); Questions 12-20 together would form a complete class definition. Please provide the parts asked for in each question. The 9 questions are shown below as they might appear on a test, but without enough room for a handwritten answer. That is because on the assignment the questions are like design specifications. What you have to hand in for this part of the assignment is a printout of the class that you have entered, compiled, and debugged on the computer.

12. The class should have the name MySquare. (Note that MySquare doesn’t have anything to do with the system supplied Rectangle class.)

13. The class should have 2 instance variables, a double called sidelength and a String called hue. (Note that hue doesn’t have anything to do with the system supplied Color class.)

14. Write a constructor that has no parameters. The easier way to do the implementation is to let the system do default initialization. You may also explicitly initialize the instance variables to suitable default values.

15. Write a constructor that takes 2 parameters, one for sidelength and one for hue.

16. Write a method called setLength() that will set the value of the sidelength instance variable.

17. Write a method called setHue() that will set the value of the hue instance variable.

18. Write a method called getLength() that will get the value of the sidelength instance variable.

19. Write a method called getHue() that will get the value of the hue instance variable.

20. Write a method called getArea() that would return the the area of an instance of MySquare by squaring the value contained in the sidelength instance variable.

Another set of problems is starting here. You will notice that this set of problems has the following characteristics:

a. Ultimately, what you’re asked to do is very similar to what you did in the sets of questions 1-8 and 12-20 above. This is repetitious. The idea is that by going through a similar process twice, you will be reinforcing your knowledge. b. The specifications are given in a way slightly different from the previous problem set. This is not critically important. The point is that test questions can be phrased in different ways. You need to have a handle on what is being asked regardless of exactly how it’s asked.

Here is the new class needed for the following questions:

public class NamedPolygon
{
private String name; private double area;

public NamedPolygon(double initarea) { name = “”; area = initarea; }

public void setName(String aname) { name = aname; }

public String getName() { return name; }

public double getArea() { return area; }
}

21. Either show the output of or explain the error in the following fragment of code which makes use of the NamedPolygon class. Give your answer in the space below.

NamedPolygon mypoly1 = new NamedPolygon(12.0);
NamedPolygon mypoly2 = new NamedPolygon(15.0); mypoly1 = mypoly2; mypoly1.setName(“box”); myterminal.println(mypoly2.getName());

Questions 22-25. Write a program that makes use of the NamedPolygon class defined above. The beginning code is provided. Follow the specifications given. You should complete the program, enter it, compile it, debug it, and run it, and hand in a copy of the source code and the test run output.

22. Print a prompt for the user to enter a name and take in a value for myname using myterminal; print a prompt for the user to enter an area and take in a value for myarea using myterminal. 23. Construct mypoly, making sure that the numerical data variable is initialized with the value obtained from the user. 24. Set the name of mypoly to the name given by the user. 25. Using the appropriate method, retrieve the value of area of mypoly, store it back into the variable myarea, and then print this value out.

public class Assignment4PolygonProg
{
public static void main(String[] args) { MyTerminalIO myterminal = new MyTerminalIO(); NamedPolygon mypoly; String myname; double myarea;