CS/120 Final Exam. Name

Transcription

1 CS/120 Final Exam Name 16 pts 1. Trace the following segment of code and to the left of each System.out.println instruction show the precise output that results when this code segment executes. java.awt.container eggnog = new Container(); eggnog.setbounds(1, 2, 3, 4); System.out.println( eggnog.getwidth() * eggnog.getheight() ); eggnog.setlocation( (int)(3 * 1.6), 7 % 3 ); System.out.println( eggnog.getx() ); System.out.println( eggnog.gety() ); int yulelog = 17; yulelog = yulelog / 3; System.out.println( yulelog ); yulelog = 5; yulelog++; yulelog++; System.out.println( yulelog ); System.out.println( (int)(3 + (-1 * Math.random())) ); yulelog = 100; for (int j=0; j!=100; j++) { yulelog = yulelog + 2; System.out.println( yulelog ); JFrame holidaywin = new JFrame("holly"); System.out.println( holidaywin == (new JFrame("holly")) );

2 Use the classes below to complete Exercises 2 through 6. public class Water { private double temperature; private double volume; public Water(double t, double v) { temperature = t; volume = v; private void makeitrun() { protected void pourit() { public class Snowball extends Snow { public Snowball(double d) { private void packit() { protected void colorityellow() { public class Snow extends Water { public Snow() { protected void colorityellow() { private void setmoisturecontent(double d) { public class Driver { private Snow flakey; private Snowball lumpy; 14 pts 2. Draw a complete class diagram showing all classes, the scope of all members, and all inheritance and aggregation relationships between the above classes. public Driver() { Snow blizzard; 4 pts 3. List the name of every method that can be called upon the this object from instructions written within the Snowball class.

3 8 pts 4. Assuming that water is a variable of type Water, snow is a variable of type Snow, snowball is a variable of type Snowball and driver is a variable of type Driver, and all have been assigned proper values; circle each of the following instructions that is valid according to the Java rules for type conformance water = snowball; snow = snowball; snowball = water; snow = driver; driver = snow; 10 pts 5. Draw an object diagram that depicts the state of computation at the time when the following segment of code has just finished execution. Water drip, droplet, stream; drip = new Water(1, 2); droplet = new Water(3, 4); stream = drip; drip = null; droplet = drip; drip = new Water(5, 6); 10 pts 6. Write the code for a gettemperature and settemperature method that could be included within the Water class in order to allow the public assignment and inspection of the temperature variable.

4 8. Assume that an array called money has exactly four cells and is used to store the amount of coins so that the first cell (i.e., the cell with lowest index) stores a number (count) of pennies, the next cell stores a number of nickels, the next a number of dimes, and the last a number of quarters. 14 pts a) Complete the following method so that when called, the method alters money to reflect that addition of one coin passed as a second argument. This parameter represents the value (in cents) of the coin. For example, a coin value of 5 means that one nickel is to be added to the previous array of coins and a coin value of 25 means a quarter is to be added. If the value of coin isn't 1, 5, 10 or 25, then your method should set every array cell to zero. private void addonecoin( int[] money, int coin ) { 8 pts b) Write a private nonvoid method that is passed a single money array, like the one above. The value returned by this method should be the total monetary value (in cents) for the money array.

5 10 pts 9. Write a private non-void method that has a single parameter that is a SimpleList of String cells. Assuming the parameter is a non-empty list, your method must return the String from the last cell of the list. 12 pts 10. Below is the skeleton of a class. Complete all code necessary so that this class animates a red ball to continuously bounce up and down. (You must assume that another object creates the ball, adds it to a JFrame more than 420 pixels in height and that the bounce method is called appropriately by an event timer object.) The ball must bounce straight up and down 100 pixels from the left edge of the JFrame. The initial falling velocity for the ball must be set to 0 pixels per timer event. For each event the ball's downward velocity increases by 2 pixels per timer event. (i.e., after the first event the ball has fallen 0 pixels, after the second event the ball has falls 2 pixels, after the third event the ball falls another 4 pixels, after the fourth event it falls an additional 6 pixels and so forth). When the ball has fallen a total of 420 pixels (this will happen exactly) from its original height of 0 pixels, then the ball reverses direction bouncing up with the same velocity that it struck the 420-pixel bottom, but when moving upward the ball's upward velocity decreases by 2 pixels at each event. When the ball reaches a height of 0 pixels it will again reverse and fall; this pattern of falling and rising continues until the program is halted. import javax.swing.*; public class BouncingBall extends JComponent { public BouncingBall() { super(); setbounds(100, 0, 10, 10); public void paint(graphics g) { g.setcolor(java.awt.color.red); g.filloval(0, 0, getwidth()-1, getheight()-1); public void bounce() {

6 12 pts 11. The Driver below is designed to create exactly one object of type Whoville and one of type Grinch. You must add all necessary declarations and instructions to these three classes so that whenever the sing method is called, it calls the hearsthesinging method upon the Driver's grinch object. Similarly, whenever the stealsgifts method is called, it must in turn call losegifts upon the Driver's whoville object. You may not use static variables, but you may alter the classes in any other way. Two of the 12 points are awarded if you can accomplish this without a callback to the Driver. public class Whoville { public void sing() { public void losegifts() { //code omitted public class Grinch { public void stealsgifts() { public void hearsthesinging() { //code omitted public class Driver { private Whoville whoville; private Grinch grinch; public Driver() { // assume other code from here calls whoville.sing() and grinch.stealgifts()

7 javax.swing.jcomponent + JComponent() + void add( Component, int ) + void remove( Component, int ) + void repaint() + void setbackground( Color ) + void setforeground( Color ) + void setbounds( int, int, int, int ) + void setlocation( int, int ) + void setsize( int, int ) + void paint( Graphics ) + int getx() + int gety() + int getwidth() + int getheight() + Color getbackground() + Color getforeground() + java.awt.container getparent()... + Container() java.awt.container + void add( Component, int ) + void remove( Component, int ) + void repaint() + void setbackground( Color ) + void setforeground( Color ) + void setbounds( int, int, int, int ) + void setlocation( int, int ) + void setsize( int, int ) + int getx() + int gety() + int getwidth() + int getheight() + Color getbackground() + Color getforeground() + java.awt.container getparent()... Rectangle + Rectangle( int, int, int, int ) + void setbackground( java.awt.color ) + void setlocation( int, int ) + void setsize( int, int ) + void repaint() + void add( java.awt.component, int ) + int getx( ) + int gety( ) + int getwidth( ) + int getheight( ) + Color getbackground( )... SimpleList<ItemType> + SimpleList<ItemType>() + void add( ItemType ) + void remove( ) + void reset( ) + boolean hasnext( ) + ItemType next( ) + int size( ) java.lang.math + double random( )