Finished all Practice Problems.

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[] animals = 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
+    animals[0] = "dog";
+    animals[1] = "cat";
+    animals[2] = "fish";
+    animals[3] = "bird";
 
     // Get the value of the array at index 2
+    System.out.println(animals[2]);
 
     // Get the length of the array
+    System.out.println(animals.length);
 
     // Iterate over the array using a traditional for loop and print out each item
+    for (int i = 0; i < animals.length; i++) {
+      System.out.println(animals[i]);
+    };
 
     // Iterate over the array using a for-each loop and print out each item
+    for (String animal : animals) {
+      System.out.println(animal);
+    };
 
     /*
      * Reminder!

src/ListPractice.java

@@ -1,27 +1,44 @@
+import java.util.ArrayList;
+
 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("Milk");
+    List.add("Eggs");
+    List.add("Bread");
 
     // 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, "Bananas");
 
     // Insert a new element at index 0 (the length of the list will change)
+    List.add(0, "Apples");
 
     // Check whether the list contains a certain string
+    boolean containsMilk = List.contains("Milk");
+    System.out.println("Contains Milk: " + containsMilk);
 
     // 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(i + " " + List.get(i));
+    };
     // Sort the list using the Collections library
+    java.util.Collections.sort(List);
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for (String s : List) {
+      System.out.println(s);
+    };
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,28 +1,46 @@
-
+import java.util.HashMap;
 
 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
-
+    HashMap<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("a", 1);
+    map.put("b", 2);
+    map.put("c", 3);
 
     // Get the value associated with a given key in the Map
+    System.out.println(map.get("a"));
 
     // Find the size (number of key/value pairs) of the Map
+    System.out.println(map.size());
 
-    // Replace the value associated with a given key (the size of the Map shoukld not change)
+    // Replace the value associated with a given key (the size of the Map should not change)
+    map.replace("a", 4);
 
     // Check whether the Map contains a given key
+    System.out.println(map.containsKey("a"));
 
     // Check whether the Map contains a given value
+    System.out.println(map.containsValue(4));
 
     // Iterate over the keys of the Map, printing each key
+    for (String key : map.keySet()) {
+      System.out.println(key);
+    };
 
     // Iterate over the values of the map, printing each value
+    for (Integer value : map.values()) {
+      System.out.println(value);
+    };
 
     // Iterate over the entries in the map, printing each key and value
+    for (HashMap.Entry<String, Integer> entry : map.entrySet()) {
+      System.out.println(entry.getKey() + " " + entry.getValue());
+    };
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -1,17 +1,27 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
+    float negFloat = -5.5f;
 
     // Create an int with a positive value and assign it to a variable
+    int posInt = 34;
 
     // Use the modulo % operator to find the remainder when the int is divided by 3
+    int remainder = posInt % 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 (remainder == 0) {
+      System.out.println("Even");
+    } else {
+      System.out.println("Odd");
+    };
 
     // Divide the number by another number using integer division
+    int division = posInt / 3;
+    System.out.println(division);
 
     /*
      * Reminder!

src/Person.java

@@ -6,13 +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 + " is " + age + " years old.";
+  }
 
 
   // Implement the below public instance method "birthYear"
@@ -28,25 +36,35 @@ 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 tyler = new Person("Tyler", 29);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person brittany = new Person("Brittany", 30);
 
     // Print the first person
+    System.out.println(tyler);
 
     // Print the second person
+    System.out.println(brittany);
 
     // Get the name of the first person and store it in a local variable
+    String personOneName = tyler.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 = tyler.birthYear(2025);
 
     // In a separate statement, print the local variable holding the birth year.
+    System.out.println(birthYear);
 
     /**
      * Terminology!

src/SetPractice.java

@@ -1,17 +1,32 @@
+import java.util.Set;
+import java.util.HashSet;
 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<String>();
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    set.add("Tyler");
+    set.add("Bonnie");
+    set.add("Brodie");
 
     // Check whether the Set contains a given String
+    boolean containsTyler = set.contains("Tyler");
+    System.out.println("Does 'set' contain Tyler? " + containsTyler);
 
     // Remove an element from the Set
+    set.remove("Tyler");
+    System.out.println(set);
 
     // Get the size of the Set
+    int size = set.size();
+    System.out.println(size);
 
     // Iterate over the elements of the Set, printing each one on a separate line
+    for (String name : set) {
+      System.out.println(name);
+    };
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,25 +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 hello = "Hello, World!";
 
     // Find the length of the string
+    hello.length();
 
     // Concatenate (add) two strings together and reassign the result
+    String goodbye = hello + " Goodbye!";
 
     // Find the value of the character at index 3
+    char charAtIndex3 = goodbye.charAt(3);
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    boolean containsWorld = goodbye.contains("World");
+    System.out.println("Does the string contain 'World'? " + containsWorld);
 
     // Iterate over the characters of the string, printing each one on a separate line
+    for (int i = 0; i < goodbye.length(); i++) {
+      System.out.println(goodbye.charAt(i));
+    };
 
     // Create an ArrayList of Strings and assign it to a variable
+    ArrayList<String> list = new ArrayList<String>();
 
     // Add multiple strings to the List (OK to do one-by-one)
+    list.add("Welcome");
+    list.add("to");
+    list.add("Green River");
 
     // 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 joined = String.join(", ", list);
+    System.out.println(joined);
 
     // Check whether two strings are equal
+    boolean isEqual = "Hello".equals("Hello");
+    System.out.println(isEqual);
 
     /*
      * Reminder!