Derusted!

src/ArrayPractice.java

@@ -1,18 +1,25 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
-
+    String[] array = 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
-
+    array[0] = "Jameson";
+    array[1] = "Auberon";
+    array[2] = "Tina";
+    array[3] = "Josh"; 
     // Get the value of the array at index 2
-
+    String index2 = array[2];
     // Get the length of the array
-
+    int arrayLength = array.length;
     // Iterate over the array using a traditional for loop and print out each item
-
+    for (int i = 0; i < array.length; i++) {
+      System.out.println(array[i]);
+    }
     // Iterate over the array using a for-each loop and print out each item
-
+    for (String string : array) {
+      System.out.println(string);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,42 @@
+import java.util.ArrayList;
+import java.util.Collections;
+
 public class ListPractice {
 
 
   public static void main(String[] args) {
     // Create an empty ArrayList of Strings and assign it to a variable of type List
-
+    ArrayList<String> list = new ArrayList<String>();
     // Add 3 elements to the list (OK to do one-by-one)
-
+    list.add("Jameson");
+    list.add("Josh");
+    list.add("Auberon");
     // Print the element at index 1
-
+    System.out.println(list.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)
-
+    list.set(1,"Tina");
     // Insert a new element at index 0 (the length of the list will change)
-
+    list.add(0, "Susan");
     // Check whether the list contains a certain string
-
+    String check = "Jameson";
+    if(list.contains(check)){
+      System.out.println("List contains " + check);
+    }else{
+      System.out.println("List does not contain " + check);
+    }
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
-
+    for (int i = 0; i < list.size(); i++) {
+      System.out.println("Index " + i + " is " + list.get(i));
+    }
     // Sort the list using the Collections library
-
+    Collections.sort(list);
     // Iterate over the list using a for-each loop
     // Print each value on a second line
-
+    for (String i : list) {
+      System.out.println(i + "\n");
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,48 @@
-
+import java.util.HashMap;
+import java.util.Map;
 
 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> map = new HashMap<String, Integer>();
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
-
+    map.put("Jameson", 18);
+    map.put("Jace", 16);
+    map.put("Lexie", 17);
     // Get the value associated with a given key in the Map
-
+    int value = map.get("Jameson");
     // Find the size (number of key/value pairs) of the Map
-
+    int size = map.size();
     // Replace the value associated with a given key (the size of the Map shoukld not change)
-
+    map.put("Jameson", 19);
     // Check whether the Map contains a given key
-
+    String testKey = "Jameson";
+    if(map.containsKey(testKey)){
+      System.out.println("Map contains " + testKey);
+    }else{
+      System.out.println("Map does not contain " + testKey);
+    }
     // Check whether the Map contains a given value
-
+    int testValue = 19;
+    if(map.containsValue(testValue)){
+      System.out.println("Map contains " + testValue);
+    }else{
+      System.out.println("Map does not contain " + testValue);
+    }
     // Iterate over the keys of the Map, printing each key
-
+    for (String i : map.keySet()) {
+      System.out.println(i);
+    }
     // Iterate over the values of the map, printing each value
-
+    for (int i : map.values()) {
+      System.out.println(i);
+    }
     // Iterate over the entries in the map, printing each key and value
-
+    for (String i : map.keySet()) {
+      System.out.println("key: " + i + ", value: " + map.get(i));
+    }
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -1,18 +1,22 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
-
+    float negativeNum = -0.5f;
     // Create an int with a positive value and assign it to a variable
-
+    int positiveNum = 10;
     // Use the modulo % operator to find the remainder when the int is divided by 3
-
+    System.out.println(positiveNum % 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.
-
+    if(positiveNum % 2 == 0){
+      System.out.println(positiveNum + " is Even");
+    }else{
+      System.out.println(positiveNum + " is Odd");
+    }
     // Divide the number by another number using integer division
-
+    System.out.println(positiveNum / 5);
     /*
      * Reminder!
      * 

src/Person.java

@@ -6,14 +6,21 @@
 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.
@@ -28,39 +35,44 @@ 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("Jameson", 18);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
-
+    Person person2 = new Person("Lexie", 17);
     // Print the first person
-
+    person.toString();
     // Print the second person
-
+    person2.toString();
     // Get the name of the first person and store it in a local variable
-
+    String name = 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 birthyear = person.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+    System.out.println(birthyear);
     /**
      * Terminology!
      * 
      * A class is the overall definition, like a blueprint.
      * An instance is a specific object made according to that definition.
      * We use "instance" and "object" to mean the same thing.
      * 
-     * For example, if there is a Person class, we can make an instance of a specific person: Auberon.
+     * For example, if there is a Person class, we can make an instance of a
+     * specific person: Auberon.
      * 
-     * There can be many instances for the same class. For example: Auberon, Xinting, Baya are all
+     * There can be many instances for the same class. For example: Auberon,
+     * Xinting, Baya are all
      * different instances of the Person class.
      * 
-     * Each instance has its own instance variables: Auberon's age can be different from Baya's age.
+     * Each instance has its own instance variables: Auberon's age can be different
+     * from Baya's age.
      */
   }
 }

src/SetPractice.java

@@ -1,18 +1,30 @@
+import java.util.HashSet;
+import java.util.Set;
+
 public class SetPractice {
   public static void main(String[] args) {
     // Create a HashSet of Strings and assign it to a variable of type Set
-
+    Set<String> set = new HashSet<>();
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
-
+    set.add("Jameson");
+    set.add("Jace");
+    set.add("Lexie");
     // Check whether the Set contains a given String
-
+    String test = "Jameson";
+    if(set.contains(test)){
+      System.out.println("Set contains " + test);
+    }else{
+      System.out.println("Set does not contain " + test);
+    }
     // Remove an element from the Set
-
+    set.remove("Jace");
     // Get the size of the Set
-
+    System.out.println(set.size());
     // Iterate over the elements of the Set, printing each one on a separate line
-
+    for (String i : set) {
+      System.out.println(i);
+    }
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,26 +1,45 @@
+import java.util.ArrayList;
+import java.util.List;
+
 public class StringPractice {
   public static void main(String[] args) {
     // Create a string with at least 5 characters and assign it to a variable
-
+    String word = "Jameson";
     // Find the length of the string
-
+    System.out.println(word.length());
     // Concatenate (add) two strings together and reassign the result
-
+    word = word + " Farmer";
     // Find the value of the character at index 3
-
+    System.out.println(word.charAt(3));
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
-
+    String test = "James";
+    if(word.contains(test)){
+      System.out.println(word + " contains " + test);
+    }else{
+      System.out.println(word + " does not contain " + test);
+    }
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for (int i = 0; i < word.length(); i++) {
+      System.out.println(word.charAt(i));
+    }
     // Create an ArrayList of Strings and assign it to a variable
-
+    List<String> list = new ArrayList<>();
     // Add multiple strings to the List (OK to do one-by-one)
-
+    list.add("Tina");
+    list.add("Josh");
+    list.add("Auberon");
     // 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 combined = String.join(", ", list);
+    System.out.println(combined);
     // Check whether two strings are equal
-
+    String test1 = "Jameson";
+    String test2 = "James"; 
+    if(test1.equals(test2)){
+      System.out.println(test1 + " equals " + test2);
+    }else{
+      System.out.println(test1 + " does not equal " + test2);
+    }
     /*
      * Reminder!
      *