csa
Tech Talk Notes Tech Talk 0 Tech Talk 1 Tech Talk 2 Tech Talk 3 Test Prep Review 2015 Test 2020 Test2020 MC
Q3
Consider the method getHours, which is intended to calculate the number of hours that a vehicle takes to travel between two mile markers on a highway if the vehicle travels at a constant speed of 60 miles per hour. A mile marker is a sign showing the number of miles along a road between some fixed location (for example, the beginning of a highway) and the current location.
The following table shows two examples of the intended behavior of getHours, based on the int parameters marker1 and marker2.
Consider the following implementation of getHours.
public static double getHours(int marker1, int marker2)
{
/* missing statement */
return hours;
}
Which of the following statements can replace /* missing statement */ so getHours works as intended?
Answer: double hours = Math.abs(marker1 - marker2) / 60.0;
Q6
Which of the following expressions evaluate to 3.5 ?
(double) 2 / 4 + 3
(double) (2 / 4) + 3
(double) (2 / 4 + 3)
Answer: I only
Q8
Consider the following class definition.
public class Points
{
private double num1;
private double num2;
public Points(int n1, int n2) // Line 6
{
num1 = n1; // Line 8
num2 = n2; // Line 9
}
public void incrementPoints(int value) // Line 12
{
n1 += value; // Line 14
n2 += value; // Line 15
}
}
The class does not compile. Which of the following identifies the error in the class definition?
Answer: In lines 14 and 15, the variables n1 and n2 are not defined.
Q11
Which of the following code segments produces the output “987654321” ?
Answer:
int num = 10;
while (num > 1)
{
num--;
System.out.print(num);
}
Q14
The following categories are used by some researchers to categorize zip codes as urban, suburban, or rural based on population density.
An urban zip code is a zip code with more than 3,000 people per square mile.
A suburban zip code is a zip code with between 1,000 and 3,000 people, inclusive, per square mile.
A rural zip code is a zip code with fewer than 1,000 people per square mile.
Consider the following method, which is intended to categorize a zip code as urban, suburban, or rural based on the population density of the area included in the zip code.
public static String getCategory(int density)
{
/* missing code */
}
Which of the following code segments can replace /* missing code */ so the getCategory method works as intended?
String cat; if (density > 3000) { cat = "urban"; } else if (density > 999) { cat = "suburban"; } else { cat = "rural"; } return cat;
String cat; if (density > 3000) { cat = "urban"; } if (density > 999) { cat = "suburban"; } cat = "rural"; return cat;
if (density > 3000) { return "urban"; } if (density > 999) { return "suburban"; } return "rural";
Answer: I and III Only
2020 FRQ
Runtime at week 7: Link to repl
FRQ 1 Code
class Hailstone{
int length;
public Hailstone(int firstNum){
length = hailstoneLength(firstNum);
}
public int getLength(){
return this.length;
}
public static int hailstoneLength(int n){
//int temp;
int temp = n;
int count = 1;
while(temp > 1){
//if (n % 2 ==0)
if(temp % 2 == 0){
temp = temp/2;
count++;
}
else{
temp = 3*temp+1;
count++;
}
}
return count;
}
public static boolean isLongSeq(int n){
if(n < hailstoneLength(n)){
return true;
}
else{
return false;
}
}
public static double propLong(int n){
int counter = 0;
int i = 1;
while(i <= n){
if(isLongSeq(i)){
counter++;
}
i++;
}
return (double)counter/(double)n;
}
public static void main(String[] args){
Hailstone one = new Hailstone(5);
Hailstone two = new Hailstone(8);
System.out.println("Length of hailstone starting with 5: " + one.getLength());
System.out.println("Length of hailstone starting with 8: " + two.getLength());
System.out.println("isLongSeq method 5: " + one.isLongSeq(5));
System.out.println("isLongSeq method 8: " + two.isLongSeq(8));
System.out.println("propLong method 10: " + one.propLong(10));
}
}
FRQ 2 Code
import java.util.*;
class GameSpinner{
private static int runs;
private static int prevspin;
private static int spinval;
private static int sectors;
public GameSpinner(int sect){
sectors = sect;
}
public static int spin(){
prevspin = spinval;
//Math.floor(Math.random()*sectors)
spinval = (int)(Math.random()*sectors + 1);
if(prevspin == spinval){
runs++;
}
else{
runs = 0;
}
return spinval;
}
public static int currentRun(){
return runs;
}
public static void main(String[] args){
System.out.println("Gamespinner created with 4 sectors");
GameSpinner game = new GameSpinner(4);
System.out.println("Spin: " + game.spin());
System.out.println("Current runs: " + game.currentRun());
System.out.println("Spin: " + game.spin());
System.out.println("Current runs: " + game.currentRun());
System.out.println("Spin: " + game.spin());
System.out.println("Current runs: " + game.currentRun());
System.out.println("Spin: " + game.spin());
System.out.println("Current runs: " + game.currentRun());
}
}
FRQ 3 Code
import java.util.*;
class ProductReview
{
private String name;
private String review;
/** Constructs a ProductReview object and initializes the instance variables. */
public ProductReview(String pName, String pReview)
{
name = pName;
review = pReview;
}
/** Returns the name of the product. */
public String getName()
{
return name;
}
/** Returns the review of the product. */
public String getReview()
{
return review;
}
}
class ReviewCollector
{
private ArrayList<ProductReview> reviewList;
private ArrayList<String> productList;
/** Constructs a ReviewCollector object and initializes the instance variables. */
public ReviewCollector()
{
reviewList = new ArrayList<ProductReview>();
productList = new ArrayList<String>();
}
/** Adds a new review to the collection of reviews, as described in Part (a). */
public void addReview(ProductReview prodReview)
{
reviewList.add(prodReview);
productList.add(prodReview.getName());
}
/** Returns the number of good reviews for a given product name, as described in Part (b). */
public int getNumGoodReviews(String prodName)
{
int good = 0;
for(ProductReview review: reviewList){
if(review.getName().contains(prodName)){
if(review.getReview().contains("best")){
good++;
}
}
}
return good;
}
public void printLists(){
System.out.print("\n");
System.out.println("Review list");
for(ProductReview review : reviewList){
System.out.println(review.getName()+": "+ review.getReview());
}
System.out.print("\n");
System.out.println("Product list");
for(String product : productList){
System.out.println(product);
}
}
// There may be instance variables, constructors, and methods not shown.
public static void main(String[] args){
ProductReview apple = new ProductReview("Apple", "best ever TBH");
ProductReview apple2 = new ProductReview("Apple", "i hate apples so bad");
ProductReview apple3 = new ProductReview("Apple", "my best friend likes apples");
ProductReview banana = new ProductReview("Banana", "Also not very good");
ProductReview nectarine = new ProductReview("Nectarine", "Kinda good");
ReviewCollector reviews = new ReviewCollector();
reviews.addReview(apple);
reviews.addReview(apple2);
reviews.addReview(apple3);
reviews.addReview(banana);
reviews.addReview(nectarine);
reviews.printLists();
System.out.print("\n");
System.out.println("Good review search for Apple: " + reviews.getNumGoodReviews("Apple"));
}
}
FRQ 4 Code
class Seat
{
private boolean available;
private int tier;
public Seat(boolean isAvail, int tierNum)
{
available = isAvail;
tier = tierNum;
}
public boolean isAvailable()
{ return available; }
public int getTier()
{ return tier; }
public void setAvailability(boolean isAvail)
{ available = isAvail; }
}
class Theater{
private Seat[][] theaterSeats;
/** Constructs a Theater object, as described in part (a).
* Precondition: seatsPerRow > 0; tier1Rows > 0; tier2Rows >= 0
*/
public Theater(int seatsPerRow, int tier1Rows, int tier2Rows)
{
theaterSeats= new Seat[tier1Rows+tier2Rows][seatsPerRow];
}
/** Returns true if a seat holder was reassigned from the seat at fromRow, fromCol
* to the seat at toRow, toCol; otherwise it returns false, as described in part (b).
* Precondition: fromRow, fromCol, toRow, and toCol represent valid row and
* column positions in the theater.
* The seat at fromRow, fromCol is not available.
*/
public boolean reassignSeat(int fromRow, int fromCol, int toRow, int toCol) {
if(theaterSeats[toRow][toCol].isAvailable()) {
int tierDestination =theaterSeats[toRow][toCol].getTier();
int tierSource =theaterSeats[fromRow][fromCol].getTier();
if(tierDestination<=tierSource) {
if(tierDestination==tierSource) {
if(fromRow<toRow) {
return false;
}else {
theaterSeats[toRow][toCol].setAvailability(false);
theaterSeats[fromRow][fromCol].setAvailability(true);
return true;
}
}
theaterSeats[toRow][toCol].setAvailability(false);
theaterSeats[fromRow][fromCol].setAvailability(true);
return true;
}else {
return false;
}
}else {
return false;
}
}
public static void main(String[] args){
Theater t1 = new Theater(3,1,2);
t1.theaterSeats[0][0] = new Seat(true,1);
t1.theaterSeats[0][1] = new Seat(false,1);
t1.theaterSeats[0][2] = new Seat(true,1);
t1.theaterSeats[1][0] = new Seat(true,2);
t1.theaterSeats[1][1] = new Seat(true,2);
t1.theaterSeats[1][2] = new Seat(true,2);
t1.theaterSeats[2][0] = new Seat(false,2);
t1.theaterSeats[2][1] = new Seat(false,2);
t1.theaterSeats[2][2] = new Seat(true,2);
System.out.println("Theater:");
for(int i=0;i<3;i++) {
for(int j=0;j<3;j++) {
System.out.print("["+i+"]"+"["+j+"] : "+t1.theaterSeats[i][j].isAvailable()+" ");
}
System.out.println();
}
System.out.println("(2,1) want to change seat to (0,0)");
System.out.println("["+2+"]"+"["+1+"]"+" to "+"["+0+"]"+"["+0+"]");
t1.reassignSeat(2, 1, 0, 0);
for(int i=0;i<3;i++) {
for(int j=0;j<3;j++) {
System.out.print("["+i+"]"+"["+j+"] : "+t1.theaterSeats[i][j].isAvailable()+" ");
}
System.out.println();
}
}
}