CS100J, Spring 2003, Assignment 1. Due on 7 February before midnight.

About Submitting assignments

Purpose

Write several JFrame subclasses (customizations) in order to practice with writing classes, methods, method calls (including the use of arguments and parameters), and expressions. We will have taught all the material required for this assignment by the end of week 2.

Ground rules

You may work with one partner.

This is (very, very roughly) a 10-hour assignment. Plan accordingly.

Plan to spend as much as an hour reading this handout so that you thoroughly understand what we are asking for. Do this with your partner before you start programming!

We strongly, strongly suggest that you and your partner alternate writing the classes. You will both benefit from this, even if you find it feels like it is taking longer.

VITAL RULES

Here are some very specific rules that you must follow. If you break any of these, you will automatically get a zero on part or all this assignment.

1. You must use the capitalization that we specify. You can ensure this by copying identifiers from this handout, rather than typing them yourself.
2. You may not use the word static anywhere in assignment 1.
3. You may not use loops or if statements.
4. Every method and class must be marked public, and every instance variable must be marked private.
5. Do not use System.out.println or System.out.print in any class that you write.

Subclasses of JFrame

You will write several subclasses of JFrame. Here are the sources of help that you can use, in no particular order: the course textbooks, your lecture notes, your programming partner, the course website, the Java APIs, the consultants in Carpenter, the TAs, and the instructor.

You should write a short javadoc comment at the top of each class that describes what the class is for. You should also write a comment for each method. As a reminder, javadoc comments look like these:

    /** this is a javadoc comment for class X */
    public class X {
    
      /** this is a javadoc comment for method m. Put a blank line before me. */
      public void m() {
      }
    }

Here are the five subclasses that you should write:

• DoublingHalvingFrame: a subclass of JFrame that can double and halve its height and width. Has these additional methods:
  • doubleDimensions(): double this window's height and width.
  • halveDimensions(): cut this window's height and width in half.

  Hints:Write and check out one method at a time. In the Interactions pane, initialize a JFrame and figure out a statement that doubles the size of that window. Then write the subclass outline, copy the statement into the method, and change the variable name to "this". Also, check your lecture notes.
  Note: doubling and halving may stop working properly if the windows become too large for your screen. Don't worry about this; your class need work only when the window is of a reasonable size.

• ResizingFrame: a subclass of JFrame that can be resized in several different ways. Has these additional methods:
  • setSizeToLoc(): set this window's width to this window's X coordinate and set this window's height to this window's Y coordinate.
  • enlarge(int dW, int dH): add dW to this window's width, and add dH to this window's height.
  • switchOrientation(): set this window's width to the height and the height to the width.

  Hints: write and test one method at a time. For example, after you write class ResizingFrame and method setSizeToLoc, try this in the Interactions pane:

      ResizingFrame rw= new ResizingFrame();
      rw.show();
      rw.setLocation(400, 400);
      rw.setSizeToLoc();

  You should see the window change shape.
  

• DateFrame: a subclass of JFrame that can get its size and location from a Date object. Has these additional methods:
  • setSizeAndLocToDate(Date d): Set this window's width to 112 + (d's year modulo 400), set this window's height to d's month times 10, set this window's X coordinate to d's hour times 10, set this window's Y coordinate to d's seconds times 5, and set this window's title to d.toString().
  Hint: Look up "modulo arithmetic" in ProgramLive's glossary. Since the numbers you are working with are nonegative, you can compute b modulo c using b % c .
  
  
• DoubleVisionFrame: a subclass of JFrame that can create a partner frame. Has these additional methods:
  • createPartner(): create a JFrame that is the same size as this frame and is 25 pixels to the right and 25 pixels down from this frame.
  • resetPartner(): resize the partner frame so that it is the same size as this fram, and move it so that it is again 25 pixels to the right and 25 pixels down from this frame. This method is called only after createPartner has been called.

  Note: The first method creates a frame; the second one doesn't. It just moves and resizes the four frames. For example, you, the user, can drag and resize the frame; then you can call resetPartner to fix its partner.
  Hint: save the partner frame as an instance variable. Draw a picture to work out the coordinates before you program it.
  You have to show the frame in the two methods; otherwise, it won't become visible.

• StarFrame: a subclass of JFrame that can create a "star" of frames around it. Has these additional methods:
  • createStar(): create 4 JFrames that are all half the size of this fram, and form a star: each of the four (exactly) touches a corner of this frame.
  • resetStar(): move and resize the 4 frames so that they are all half the size of this fram, and form a star: each of the four (exactly) touches a corner of this frame. This method is called only after createStar has been called.

  Hint: save the partner framesas instance variables. Draw pictures to work out the coordinates.

What to submit

• DoublingHalvingFrame.java,
• ResizingFrame.java,
• DateFrame.java,
• DoubleVisionFrame.java,
• StarFrame.java.