Finished derusting

src/ArrayPractice.java

@@ -1,17 +1,30 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
+    String[] pets = new String[4];
 
     // Set the value of the array at each index to be a different String
     // It's OK to do this one-by-one
+    pets[0] = "cat";
+    pets[1] = "dog";
+    pets[2] = "parrot";
+    pets[3] = "hamster";
 
     // Get the value of the array at index 2
+    System.out.println(pets[2]);
 
     // Get the length of the array
+    System.out.println(pets.length);
 
     // Iterate over the array using a traditional for loop and print out each item
+    for (int i = 0; i < pets.length; i++){
+      System.out.println(pets[i]);
+    }
 
     // Iterate over the array using a for-each loop and print out each item
+    for (String pet : pets){
+      System.out.println(pet);
+    }
 
     /*
      * Reminder!

src/ListPractice.java

@@ -1,27 +1,46 @@
+import java.util.*;
 public class ListPractice {
 
 
   public static void main(String[] args) {
     // Create an empty ArrayList of Strings and assign it to a variable of type List
+    List<String> fruits = new ArrayList<String>();
 
     // Add 3 elements to the list (OK to do one-by-one)
+    fruits.add("Apple");
+    fruits.add("Pear");
+    fruits.add("Grape");
 
     // Print the element at index 1
+    System.out.println(fruits.get(1));
 
     // Replace the element at index 1 with a new value
     // (Do not insert a new value. The length of the list should not change)
+    fruits.set(1, "Banana");
+    System.out.println(fruits.get(1));
 
     // Insert a new element at index 0 (the length of the list will change)
+    fruits.add(0, "Pinapple");
+    System.out.println(fruits);
 
     // Check whether the list contains a certain string
+    System.out.println(fruits.contains("Pear"));
 
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
+    for (int i = 0; i < fruits.size(); i++){
+      System.out.println("Index: " + i + ", Fruit: " + fruits.get(i));
+    }
+
 
     // Sort the list using the Collections library
+    Collections.sort(fruits);
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for (String fruit : fruits){
+      System.out.println(fruit);
+    }
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,28 +1,47 @@
-
+import java.util.*;
 
 public class MapPractice {
   public static void main(String[] args) {
     // Create a HashMap with String keys and Integer values and
     // assign it to a variable of type Map
+    Map<String, Integer> orders = new HashMap<String, Integer>();
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
+    orders.put("Tea", 3);
+    orders.put("Coffee", 1);
+    orders.put("Smoothie", 1);
 
     // Get the value associated with a given key in the Map
+    System.out.println(orders.get("Smoothie"));
 
     // Find the size (number of key/value pairs) of the Map
+    System.out.println(orders.size());
 
     // Replace the value associated with a given key (the size of the Map shoukld not change)
+    orders.put("Tea", 5);
+    System.out.println(orders);
 
     // Check whether the Map contains a given key
+    System.out.println(orders.containsKey("Coffee"));
 
     // Check whether the Map contains a given value
+    System.out.println(orders.containsValue(3));
 
     // Iterate over the keys of the Map, printing each key
+    for (int quantity : orders.values()){
+      System.out.println(quantity);
+    }
 
     // Iterate over the values of the map, printing each value
+    for (String drink : orders.keySet()){
+      System.out.println(drink);
+    }
 
     // Iterate over the entries in the map, printing each key and value
+    for (Map.Entry<String, Integer> order : orders.entrySet()){
+      System.out.println(order.getKey() + ": " + order.getValue());
+    }
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -1,25 +1,35 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
+    float floatNum = -1.12f;
 
     // Create an int with a positive value and assign it to a variable
+    int intNum = 9;
 
     // Use the modulo % operator to find the remainder when the int is divided by 3
-
+    int remainder = intNum % 3;
+
     // Use the modulo % operator to determine whether the number is even
     // (A number is even if it has a remainder of zero when divided by 2)
     // Use an if-else to print "Even" if the number is even and "Odd"
     // if the number is odd.
+    String evenOrOdd = "";
+    if (intNum % 2 == 0){
+      evenOrOdd = "Number is even";
+    } else {
+      evenOrOdd = "Number is odd";
+    }
 
     // Divide the number by another number using integer division
-
     /*
      * Reminder!
      * 
      * When dividing ints, the result is rounded down.
      * Example: 
      * 7 / 3 = 2 when performing int division
      */
+    int divided = intNum / 2;
 
+     System.out.println(floatNum + ", " + intNum + ", " + remainder + ", " + evenOrOdd + ", " + divided );
   }
 }

src/Person.java

@@ -6,14 +6,20 @@
 public class Person {
   // Declare a public String instance variable for the name of the person
   // Declare a private int instance variable for the age of the person
-
+  public String name;
+  private int age;
 
   // Create a constructor that takes the name and age of the person
   // and assigns it to the instance variables
-
+  public Person(String name, int age){
+    this.name = name;
+    this.age = age;
+  }
 
   // Create a toString method that gives the name and age of the person
-
+  public String toString(){
+    return "Name: " + name + ", Age: " + age;
+  }
 
   // Implement the below public instance method "birthYear"
   // There should NOT be any print statement in this method.
@@ -28,25 +34,34 @@ public class Person {
    * @return The year the person was born
    */
   // (create the instance method here)
-
+  public int birthYear(int currentYear){
+    return currentYear - age;
+  }
 
   public static void main(String[] args) {
     // Create an instance of Person
+    Person person = new Person("Bob", 13);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person person2 = new Person("Garry", 31);
 
     // Print the first person
+    System.out.println(person);
 
     // Print the second person
+    System.out.println(person2);
 
     // Get the name of the first person and store it in a local variable
+    String personName = person.name;
 
     // Using the birthYear method, get the birth year of the first person
     // and store it in a local variable. Input the actual current year (e.g. 2025)
     // as the argument.
+    int personBirthYear = person.birthYear(2025);
 
     // In a separate statement, print the local variable holding the birth year.
+    System.out.println("Name: " + personName + ", Birth Year: " + personBirthYear);
 
     /**
      * Terminology!

src/SetPractice.java

@@ -1,17 +1,30 @@
+import java.util.*;
 public class SetPractice {
   public static void main(String[] args) {
     // Create a HashSet of Strings and assign it to a variable of type Set
+    HashSet<String> instruments = new HashSet<String>();
+
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    instruments.add("piano");
+    instruments.add("guitar");
+    instruments.add("violin");
 
     // Check whether the Set contains a given String
+    System.out.println(instruments.contains("violin"));
 
     // Remove an element from the Set
+    instruments.remove("guitar");
+    System.out.println(instruments);
 
     // Get the size of the Set
+    System.out.println(instruments.size());
 
     // Iterate over the elements of the Set, printing each one on a separate line
+    for (String instrument : instruments){
+      System.out.println(instrument);
+    }
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,25 +1,46 @@
+import java.util.*;
 public class StringPractice {
   public static void main(String[] args) {
     // Create a string with at least 5 characters and assign it to a variable
+    String name = "eliza";
 
     // Find the length of the string
+    System.out.println(name.length());
 
     // Concatenate (add) two strings together and reassign the result
+    String name2 = "beth";
+    name = name + name2;
+    System.out.println(name);
 
     // Find the value of the character at index 3
+    System.out.println(name.charAt(3));
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    System.out.println(name.contains("abc"));
 
     // Iterate over the characters of the string, printing each one on a separate line
+    for(char letter : name.toCharArray()){
+      System.out.println(letter);
+    }
 
     // Create an ArrayList of Strings and assign it to a variable
+    ArrayList<String> lastName = new ArrayList<String>();
 
     // Add multiple strings to the List (OK to do one-by-one)
+    lastName.add("Potter");
+    lastName.add("Granger");
+    lastName.add("Weasley");
+    lastName.add("Malfoy");
 
     // Join all of the strings in the list together into a single string separated by commas
     // Use a built-in method to achieve this instead of using a loop
+    //String words = String.join(", ", lastName);  
+    String lastNameString = String.join(", ", lastName);
+    String words = "Potter, Granger, Weasley, Malfoy";
+    System.out.println(lastNameString);
 
     // Check whether two strings are equal
+    System.out.println(lastNameString.equals(words));
 
     /*
      * Reminder!

toRefresh.md

@@ -2,4 +2,7 @@
 
 As you work through this exercise, write down anything that you needed to look up or struggled to remember here. It can be just a word or two (e.g. "joining strings"). You can use this as a guide of what to make extra sure you're refreshed on before exams and interviews.
 
+Looked up how float number is being defined.
+Looked up how to iterate through a string using a for each loop.
+Looked up how to iterate trhoug a HashMap using a for each loop.
 -