Charlie FRQ Key Learnings - yajatyadav/intellijs GitHub Wiki
Unit 2
public String insertSegment(String segment, int ind){
int IndexOF = oldSeq.indexOf(segment);
String newSeq = oldSeq.substring(0, IndexOF) + oldSeq.substring(IndexOF + segment.length());
System.out.println(newSeq);
return newSeq;
}- In this FRQ, I learned about how to use indexes of previous strings to construct new strings
gradShow.display(); // part b- I also learned how to call objects like with the above code
LightSequence gradShow = new LightSequence("0101 0101 0101");- It also taught me how to construct new objects like this construction of the LightSequence object with the parameter "0101 0101 0101" being passed into it.
Unit 3
public class frq3{
public String option1;
public void attending(boolean rsvp){
if(rsvp){
System.out.println("attending");
}
else {
System.out.println("not attending");
System.exit(0);
}
}
public void meal(int selection){
if(selection == 1){
option1 = "Thanks for attending. You will be served beef.";
}
else if(selection == 2){
option1 = "Thanks for attending. You will be served chicken.";
}
else if(selection == 3){
option1 = "Thanks for attending. You will be served pasta.";
}
else{
option1 = "Thanks for attending. You will be served fish.";
}
System.out.println(option1);
}
}- In these FRQs, I practiced implementing if/else statements and conditionals.
- I also practiced setting the variable option 1 to different strings based on the user's selection
else if(answer.equals("n")){
rsvp = false;
System.out.println("Sorry you can't attend.");
}- I also practiced using .equals as shown above with strings to check if the strings inputted are the same.
public static void drawSquare(int x, int y, int len) {
if(x+len>10)
len = 10-x;
if(y+len>10)
len = 10-y;
System.out.println("side length = " + len + ", area = " + len*len);
drawLine(x, y, x+len, y);
drawLine(x+len,y,x+len,y-len);
drawLine(x+len, y-len, x, y-len);
drawLine(x, y-len, x, y);
}- In the second FRQ, I practiced calling a methods inside a method to accomplish a particular task
- I used concatenation and math operations within the print statement to correctly display side length and area.
- I also practiced with conditionals to check if the square actually fit into the box
Unit 4
public class frq4_1{
public static String longestStreak(String str){
char previousChar = ' ';
String largestStreak = "", currentStreak = "";
for (int i = 0; i < str.length(); i++){
if (str.charAt(i) != previousChar){
currentStreak = "";
}
currentStreak += str.charAt(i);
if (currentStreak.length() > largestStreak.length()){
largestStreak = currentStreak;
}
previousChar = str.charAt(i);
}
return (largestStreak.charAt(0)+" "+largestStreak.length());
}
}- In this FRQ, I learned how to use a for loop with specific conditions to write an algorithm
- I used different if statements and variables to track the longest streak of letters and retain the longest streak while traversing down the String
public class frq4_2 {
private int startingCoins; // starting number of coins
private int maxRounds; // maximum number of rounds played
public frq4_2(int s, int r)
{
startingCoins = s;
maxRounds = r;
}
/** Returns the number of coins (1, 2, or 3) that player 1 will spend.
*/
public int getPlayer1Move(int round){
int result = 1;
if (round % 3 == 0){
result = 3;
}
else if (round % 2 == 0){
result = 2;
}
return result;
}
/** Returns the number of coins (1, 2, or 3) that player 2 will spend, as described in part (a).
*/
public int getPlayer2Move(int round){
int result = 1;
if (round % 3 == 0){
result = 3;
}
else if (round % 2 == 0){
result = 2;
}
return result;
}
/** Plays a simulated game between two players, as described in part (b).
*/
public void playGame() {
int Roundnumber = 1;
int r = 1;
int p1coins = startingCoins;
int p2coins = startingCoins;
while (Roundnumber <= maxRounds && p1coins >= 3 && p2coins >= 3){
p1coins -= getPlayer1Move(r);
p2coins -= getPlayer2Move(r);
if(Math.abs(getPlayer1Move(r) - getPlayer2Move(r)) == 1){
p2coins += 1;
}
else if(Math.abs(getPlayer1Move(r) - getPlayer2Move(r)) == 2){
p1coins += 2;
}
}
if (p1coins > p2coins){
System.out.println("player 1 wins");
}
else if (p1coins < p2coins){
System.out.println("player 2 wins");
}
else{
System.out.println("tie game");
}
}
}- In this FRQ, I learned how to use compound boolean expressions to ensure multiple criteria were met
- While loops were also used to check that if maxrounds are reached or if any player's coins fall below 3
- Conditionals in the loop were also used to update the player's coin values correctly
Unit 5
public class frq5_1 {
private String hostName;
private String address;
public frq5_1(String n, String a)
{
hostName = n;
address = a;
}
public String getHostName(){
return hostName;
} //part 1a
public String updateAddress(String newAddress) { //part 1b
String newaddress = newAddress;
return newaddress;
}
public String whoInvited( String personInvited){
String personInvited1 = personInvited;
String greeting = "Dear " + personInvited1 + ", please attend my event at " + address + ". See you then, " + hostName;
System.out.println(greeting);
return greeting;
}
}- In this FRQ, I learnt about the anatomy of a class, including how to use instance variables and methods
- I created mutator methods to update the address, which would make a new address and return it.
- I also practiced writing accessor methods and using concatenation
import java.util.Random;
public class frq5_2 {
private static Random random = new Random();
private String prefix;
private static int passwordsGenerated =0;
private int length;
public frq5_2(int length,String prefix) {
this.prefix = prefix;
this.length = length;
}
public frq5_2(int length) {
this.prefix = "A";
this.length = length;
}
public String pwGen(){
String pwd= this.prefix+".";
for(int i=1;i<=this.length;i++){
pwd+=random.nextInt(10);
}
passwordsGenerated+=1;
return pwd;
}
public int pwCount(){
return passwordsGenerated;
}
public static void main(String[] args) {
frq5_2 pw1 = new frq5_2(4,"chs");
System.out.println(pw1.pwGen());
System.out.println(pw1.pwCount());
System.out.println(pw1.pwGen());
System.out.println(pw1.pwCount());
frq5_2 pw2 = new frq5_2(6);
System.out.println(pw2.pwCount());
System.out.println(pw2.pwGen());
System.out.println(pw2.pwCount());
System.out.println(pw1.pwCount());
}
}- In this FRQ, I again practiced loops, this time to generate different passwords
- I also learned how to use the Math.random() function with casting and multiplication to get a custom range of random numbers
- Finally, I learnt how to use a static variable to count how many times the class was instantiated, and therefore print the count of the passwords generated in main.
Unit 6
public static void main(String[] args) {
String ing[] = {"ten","fading","post","card","thunder","hinge","trailing","batting"};
for (String i: ing){
if (i.endsWith("ing")){
System.out.println(i);
}
}
}- In this FRQ, I learned how to use an enhanced for loop to go through an array
- I also learned how to use the .endsWith function in a conditional to check for the end of the word
// unit 6, question 2
// part a
public double computeBonusThreshold() {
int total = itemsSold[0];
int min = itemsSold[0];
int max = itemsSold[0];
for(int i = 1; i < itemsSold.length; i++) {
total += itemsSold[i];
if(itemsSold[i] < min) {
min = itemsSold[i];
}
if(itemsSold[i] > max) {
max = itemsSold[i];
}
}
System.out.println((total - min - max) / (double) (itemsSold.length - 2));
return (total - min - max) / (double) (itemsSold.length - 2);
}
// part b
public void computeWages(double fixedWage, double perItemWage) {
double threshold = computeBonusThreshold();
for(int i = 0; i < itemsSold.length; i++) {
double baseWage = fixedWage + perItemWage * itemsSold[i];
if(itemsSold[i] > threshold) {
wages[i] = baseWage * 1.1;
}
else {
wages[i] = baseWage;
}
}
}- I also wrote a method to iterate through an array and print the contents
- I also used math operators to return a value from the method computeBonusThreshhold
- Used a loop to find the average items sold to return that value
- Used a for loop and conditionals to set the values in an array
Unit 7
import java.util.ArrayList;
public class frq7
{
// The list of possible user names, based on a user’s first and last names and initialized by the constructor.
private ArrayList<String> possibleNames;
/** Constructs a UserName object as described in part (a).
* Precondition: firstName and lastName have length greater than 0
* and contain only uppercase and lowercase letters.
*/
public frq7(String firstName, String lastName){
for(int x = firstName.length();x >= 1;x--){
possibleNames.add(lastName + firstName.substring(0,x));
}
}
/** Returns true if arr contains name, and false otherwise. */
public boolean isUsed(String name, String[] arr){
for(String x: arr){
if (name.equals(x)){
return true;
}
}
return false;
}
/** Removes strings from possibleNames that are found in usedNames as described in part (b).
*/
public void setAvailableUserNames(String[] usedNames){
for(int x = 0; x < possibleNames.size(); x++){
if (isUsed(possibleNames.get(x) , usedNames)){
possibleNames.remove(x);
x--;
}
}
}
}- I learned how to use a for loop to traverse an ArrayList
- different ArrayList methods (add, remove) to check and compare specific values
- used an enhanced for loop with String.equals()
- learned how to manage the index to ensure that each item was check in an ArrayList if an item was deleted
Unit 8
public Plot getHighestYield(String c){
Plot plot = null;
int highest = this.farmPlots[0][0].getCropYield();
for(int i=0;i<4;i++){
for(int j=0;j<3;j++){
if(farmPlots[i][j].getCropType().equalsIgnoreCase(c) && farmPlots[i][j].getCropYield()>highest){
highest = farmPlots[i][j].getCropYield();
plot = farmPlots[i][j];
}
}
}
if(plot != null){
return plot;
}
else{
return null;
}
}- In this FRQ, I practiced using two for loops to traverse a 2d array
- I learned how a 2D array is an array of arrays, and how to index row and columns using that knowledge
- Used compound boolean expressions to check multiple conditions
- Checked and modified values in a 2d array by using row and col indeces
public boolean sameCrop(int col){
boolean hello = true;
String crop = farmPlots[0][col].getCropType();
for (int i = 0; i<4; i++){
if(!farmPlots[i][col].getCropType().equalsIgnoreCase(crop)){
hello = false;
break;
}
}
return hello;
}- Here, I wrote a method that could traverse down a specific column of a 2d array and check the values
- practiced Boolean algebra and String methods
Unit 9
import java.util.ArrayList; class frq9pic extends frq9{ private String illustrator; public frq9pic(String t, String a, String i){ super(t, a); illustrator = i; } public void printBookInfo(){ super.printBookInfo(); System.out.println(" and illustrated by " + illustrator); } public static void main(String[] args){ ArrayList myLibrary = new ArrayList(); frq9 book1 = new frq9("Frankenstein", "Mary Shelley"); frq9 book2 = new frq9pic("The Wonderful Wizard of Oz", "L. Frank Baum", "W.W. Denslow"); myLibrary.add(book1); myLibrary.add(book2);
}
}
* In this FRQ, I practiced class inheritance
* used the extends keyword to create a child class
* created a subclass constructor that contains a reference to the super constructor to initialize the variables inherited from the parent class
* used the this keyword in the constructor
* Wrote a print method that overrrid superclass's method implementation, and called the super method inside it as well (using super keyword)
* practiced creating an ArrayList of Objects, and adding both parent and subclass objects to this arraylist, by having the declared type be different from the constructor (late binding)
``` java
// book listing class for unit 9, frq 1, part c
class frq9list{
private frq9 book;
private double price;
public frq9list(frq9 book, double price){
book = book;
price = price;
}
public void printDescription(){
book.printBookInfo();
System.out.println(", " + price);
}
public static void main(String[] args){
frq9 book1 = new frq9("Frankenstein", "Mary Shelley");
frq9pic book2 = new frq9pic("The Wonderful Wizard of Oz", "L. Frank Baum", "W.W. Denslow");
frq9list listing1 = new frq9list(book1, 10.99);
listing1.printDescription();
frq9list listing2 = new frq9list(book2, 12.99);
listing2.printDescription();
}
}
- In this part, I implemented the subclasses' methods in a new class to have different print messages be displayed, based on which printBookInfo method was called upon runtime (parent class method or subclass overridden method)
Unit 9
public class Animal {
private String eats;
private String species;
private String name;
public Animal(String e, String s, String n){
eats = e;
species = s;
name = n;
}
public String toString(){
return(name + " the " + species + " is a " + eats);
}
}- In this part, I revised the anatomy of a class, creating a constructor and writing a method based on the instance variables
public class Herbivore extends Animal{
public Herbivore(String species, String name){
super("herbivore", species, name);
}
}- Here, I practiced Inheritance in Java
- Specifically, I wrote the child class constructor to call the super constructor with specific parameters unique to the child class's implementation
public class Elephant extends Herbivore{
private int tusklength;
public Elephant(String name, int tl){
super("elephant", name);
tusklength = tl;
}
public String toString(){
return super.toString() + " with tusks that are " + tusklength + " meters long";
}
}- Continued to practice inheritance, created a child class of a child class, and created a constructor referring to the parent class's constructor
- also wrote a method that called on the parent class's toString method (using super keyword), which it inherited from its parent class (Animal class)
Unit 10
public class frq10 {
public static int gcf(int a, int b){
if(a%b == 0){
return b;
}
else{
return(gcf(b,a%b));
}
}
public static String reduceFraction(int numerator, int denominator){
if (numerator%denominator == 0){
return (numerator + "/" + denominator + " reduces to " + numerator/denominator);
}
else{
int numerator2 = numerator/gcf(numerator, denominator);
int denominator2 = denominator/gcf(numerator, denominator);
return (numerator + "/" + denominator + " reduces to " + numerator2 + "/" + denominator2);
}
}
}- In this unit, I practiced using recursion to create an algorithm
- using the given math knowledge, I wrote the GCF function to find the greatest common factor between 2 numbers
- In this function, I used if else statements, with the if containing the base case (remainder = 0) and the else containing the recursive call with new parameters
- using the GCF function, I wrote a fraction reducing method
- again, the if had the base case that fraction is already reduced (remainder b/w num and denom is 0) to return the original fraction
- the else contained a call to GCF with the numerator and denominator, which would keep recursing until it found the GCF, and then use this info to reduce the fraction and then print it