completed all practice exercises

src/ArrayPractice.java

@@ -1,18 +1,40 @@
-public class ArrayPractice {
-  public static void main(String[] args) {
+public class ArrayPractice 
+{
+  public static void main(String[] args) 
+  {
     // Create an array of Strings of size 4
+    String[] newArray = 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
+    newArray[0] = "apple";
+    newArray[1] = "banana";
+    newArray[2] = "strawberry";
+    newArray[3] = "pear";
 
     // Get the value of the array at index 2
 
+    String value = newArray[2];
+    System.out.println(value);
+
     // Get the length of the array
 
+    int length = newArray.length;
+    System.out.println(length);
+
     // Iterate over the array using a traditional for loop and print out each item
 
-    // Iterate over the array using a for-each loop and print out each item
+    for(int i=0; i<newArray.length; i++)
+    {
+      System.out.println(newArray[i]);
+    }
 
+    // Iterate over the array using a for-each loop and print out each item
+    for(String fruit: newArray)
+    {
+      System.out.println(fruit);
+    }
+
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,27 +1,57 @@
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
 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> newList = new ArrayList<>();
 
     // Add 3 elements to the list (OK to do one-by-one)
 
+    newList.add("apple");
+    newList.add("banana");
+    newList.add("orange");
+
     // Print the element at index 1
 
+    System.out.println(newList.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)
 
+    newList.set(1, "pear");
+
     // Insert a new element at index 0 (the length of the list will change)
 
+    newList.set(0, "strawberry");
+
     // Check whether the list contains a certain string
 
+    boolean check = newList.contains("orange");
+    System.out.println(check); 
+
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
 
+    for(int i=0; i<newList.size(); i++)
+    {
+      System.out.println("index: " + i + ", value: " + newList.get(i));
+    }
+
     // Sort the list using the Collections library
 
+    Collections.sort(newList);
+
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for(String fruit: newList)
+    {
+      System.out.println(fruit);
+    }
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,28 +1,65 @@
-
+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> newMap = new HashMap<>();
+
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
 
+    newMap.put("bob", 25);
+    newMap.put("tom", 30);
+    newMap.put("jim", 28);
+
     // Get the value associated with a given key in the Map
 
+    int value = newMap.get("tom");
+    System.out.println(value);
+
     // Find the size (number of key/value pairs) of the Map
 
+    int size = newMap.size();
+    System.out.println(size);
+
     // Replace the value associated with a given key (the size of the Map shoukld not change)
 
+    newMap.put("tom", 22);
+
     // Check whether the Map contains a given key
 
+    boolean checkKey = newMap.containsKey("tom");
+    System.out.println(checkKey);
+
     // Check whether the Map contains a given value
 
+    boolean checkValue = newMap.containsValue(22);
+    System.out.println(checkValue);
+
     // Iterate over the keys of the Map, printing each key
 
+    for(String key: newMap.keySet())
+    {
+      System.out.println(key);
+    }
+
     // Iterate over the values of the map, printing each value
 
+    for(Integer values: newMap.values())
+    {
+      System.out.println(values);
+    }
+
     // Iterate over the entries in the map, printing each key and value
+
+    for (Map.Entry<String,Integer> entry : newMap.entrySet()) 
+    {
+
+      System.out.println("key: " + entry.getKey() + ", value: " + entry.getValue());
+    }
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -2,17 +2,38 @@ public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
 
+    float num1 = -42.3f;
+    System.out.println(num1);
+
     // Create an int with a positive value and assign it to a variable
 
+    int num2 = 7;
+    System.out.println(num2);
+
     // Use the modulo % operator to find the remainder when the int is divided by 3
 
+    int remainder = num2 % 3;
+    System.out.println(remainder);
+
     // 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 (num2 % 2 == 0)
+    {
+      System.out.println("Even");
+    }
+    else{
+      System.out.println("Odd");
+    }
+
     // Divide the number by another number using integer division
 
+    int sum = num2 / 3;
+    System.out.println(sum);
+
+
     /*
      * Reminder!
      * 

src/Person.java

@@ -7,13 +7,28 @@ 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.
@@ -29,24 +44,44 @@ public class Person {
    */
   // (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 person1 = new Person("Bob", 25);
+
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
 
+    Person person2 = new Person("Jim", 20);
+
     // Print the first person
 
+    System.out.println(person1.toString());
+
     // Print the second person
 
+    System.out.println(person2.toString());
+
     // Get the name of the first person and store it in a local variable
 
+    String name = person1.name;
+    System.out.println(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 bYear = person1.birthYear(2025);
+
+
     // In a separate statement, print the local variable holding the birth year.
+    System.out.println("birth year: " + bYear);
 
     /**
      * Terminology!

src/SetPractice.java

@@ -1,18 +1,43 @@
-public class SetPractice {
-  public static void main(String[] args) {
+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> newSet = new HashSet<>();
+
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
 
+    newSet.add("apple");
+    newSet.add("banana");
+    newSet.add("orange");
+
     // Check whether the Set contains a given String
 
+    boolean check = newSet.contains("apple");
+    System.out.println(check);
+
     // Remove an element from the Set
 
+    newSet.remove("orange");
+
+
     // Get the size of the Set
 
+    int size = newSet.size();
+    System.out.println("Size: " + size);
+
     // Iterate over the elements of the Set, printing each one on a separate line
 
+    for(String fruit: newSet)
+    {
+      System.out.println(fruit);
+    }
+
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,26 +1,65 @@
+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 name = "Matthew";
+    System.out.println(name);
+
     // Find the length of the string
 
+    int length = name.length();
+    System.out.println("length: " + length);
+
+
     // Concatenate (add) two strings together and reassign the result
 
+    String word1 = "hello";
+    String word2 = "world";
+    String word3 = word1 + word2;
+    System.out.println(word3);
+
     // Find the value of the character at index 3
 
+    char value = word3.charAt(3);
+    System.out.println("character at index 3: " + value);
+
+
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
 
+    boolean contains = word3.contains("low");
+    System.out.println(contains);
+
     // Iterate over the characters of the string, printing each one on a separate line
 
+    for (int i = 0; i < word3.length(); i++) 
+    {
+      System.out.println(word3.charAt(i));
+    }
+
     // Create an ArrayList of Strings and assign it to a variable
 
+    List<String> newList = new ArrayList<>();
+
     // Add multiple strings to the List (OK to do one-by-one)
+    newList.add("apple");
+    newList.add("banana");
+    newList.add("strawberry");
+    newList.add("orange");
 
     // 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(", ", newList);
+    System.out.println(joined);
+
     // Check whether two strings are equal
 
+    boolean test = word1.equals(word2);
+    System.out.println(test);
+
     /*
      * Reminder!
      *