Java Derusting Assignment Finished.

src/ArrayPractice.java

@@ -1,18 +1,26 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
-
+    String[] myArr = 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
+    myArr[0] = "Hello";
+    myArr[1] = "Bonjour";
+    myArr[2] = "Hola";
+    myArr[3] = "Salam";
 
     // Get the value of the array at index 2
-
+    System.out.println("Value at index 2: " + myArr[2]);
     // Get the length of the array
-
+    System.out.println("Length of the array: " + myArr.length);
     // Iterate over the array using a traditional for loop and print out each item
-
+    for (int i = 0; i < myArr.length; i++) {
+      System.out.println(myArr[i]);
+    }
     // Iterate over the array using a for-each loop and print out each item
-
+    for (String item : myArr) {
+      System.out.println(item);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,41 @@
+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> myList = new ArrayList<>();
     // Add 3 elements to the list (OK to do one-by-one)
-
+    myList.add("Apple");
+    myList.add("Cherry");
+    myList.add("Banana");
     // Print the element at index 1
-
+    System.out.println("Element at index 1: " + myList.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)
-
+    myList.set(1, "Strawberry");
+    System.out.println("Size of the List after the first insertion: " + myList.size());
     // Insert a new element at index 0 (the length of the list will change)
-
+    myList.set(0, "Kiwi");
+    System.out.println("Size of the List after the second insertion: " + myList.size());
     // Check whether the list contains a certain string
-
+    System.out.println(myList.contains("Apple"));
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
-
+    for (int i = 0; i < myList.size(); i++) {
+      System.out.println("Index " + i + ": " + myList.get(i));
+    }
     // Sort the list using the Collections library
-
+    Collections.sort(myList);
+    System.out.println("Sorted List: " + myList);
     // Iterate over the list using a for-each loop
     // Print each value on a second line
-
+    for (String fruit : myList) {
+      System.out.println(fruit);
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,39 @@
-
+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> myMap = new HashMap<>();
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
-
+    myMap.put("Alice", 75);
+    myMap.put("Brandon", 88);
+    myMap.put("Emily", 96);
     // Get the value associated with a given key in the Map
-
+    System.out.println("Valued assosiated with a given key of 'Alice': " + myMap.get("Alice"));
     // Find the size (number of key/value pairs) of the Map
-
-    // Replace the value associated with a given key (the size of the Map shoukld not change)
-
+    System.out.println("Size of the Map: " + myMap.size());
+    // Replace the value associated with a given key (the size of the Map should not change)
+    myMap.put("Alice", 76);
+    System.out.println("Updated value for 'Alice' key: " + myMap.get("Alice"));
     // Check whether the Map contains a given key
-
+    System.out.println("Does the Map contains the key 'Edward'? " + myMap.containsKey("Edward"));
     // Check whether the Map contains a given value
-
+    System.out.println("Does the Map contains the value 88? " + myMap.containsValue(88));
     // Iterate over the keys of the Map, printing each key
-
+    for (String key : myMap.keySet()) {
+      System.out.println(key);
+    }
     // Iterate over the values of the map, printing each value
-
+    for (Integer value : myMap.values()) {
+      System.out.println(value);
+    }
     // Iterate over the entries in the map, printing each key and value
-
+    for (Map.Entry<String, Integer> entry : myMap.entrySet()) {
+      System.out.println("Key: " + entry.getKey() + " | Value: " + entry.getValue());
+    }
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -1,18 +1,24 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
+    float floatNum = -7.7f;
 
     // 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.
-
+    if (intNum % 2 == 0) {
+      System.out.println("Even");
+    } else {
+      System.out.println("Odd");
+    }
     // Divide the number by another number using integer division
-
+    int divResult = 6 / 2;
+    System.out.println("Result of the division by 2: " + divResult);
     /*
      * Reminder!
      * 

src/Person.java

@@ -6,48 +6,56 @@
 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
-
-
+  @Override
+  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.
   /**
    * birthYear returns the year the person was born.
    * 
-   * The birth year is calculated by subtracting the person's age from currentYear
+   * The birth year is calculated by subtracting the person's age from current Year
    * that's passed in as an int. It assumes that the person's birthday has already
    * passed this year.
    * 
    * @param currentYear an int for the current year
    * @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 firstPerson = new Person("Ali", 22);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
-
+    Person secondPerson = new Person("Mark", 18);
     // Print the first person
-
+    System.out.println(firstPerson);
     // Print the second person
-
+    System.out.println(secondPerson);
     // Get the name of the first person and store it in a local variable
-
+    String firstPersonName = firstPerson.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 firstPersonBirthYear = firstPerson.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+    System.out.println(firstPersonName + "'s Birth year: " + firstPersonBirthYear);
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,18 +1,25 @@
+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> mySet = new HashSet<>();
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
-
+    mySet.add("Math");
+    mySet.add("English");
+    mySet.add("Music");
     // Check whether the Set contains a given String
-
+    System.out.println("Does the Set contains Math? " + mySet.contains("Math"));
     // Remove an element from the Set
-
+    mySet.remove("Math");
     // Get the size of the Set
-
+    System.out.println("Size of the Set: " + mySet.size());
     // Iterate over the elements of the Set, printing each one on a separate line
-
+    for (String subject : mySet) {
+      System.out.println(subject);
+    }
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,26 +1,35 @@
+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 myWord = "Welcome";
     // Find the length of the string
-
+    System.out.println("Length of the Word: " + myWord.length());
     // Concatenate (add) two strings together and reassign the result
-
+    myWord = myWord + " Friend";
+    System.out.println("Concatenated String: " + myWord);
     // Find the value of the character at index 3
-
+    System.out.println("Value of the character at index 3 is " + myWord.charAt(3));
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
-
+    System.out.println("Does the String have 'abc' in it? " + myWord.contains("abc"));
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for (int i = 0; i < myWord.length(); i++) {
+      System.out.println(myWord.charAt(i));
+    }
     // Create an ArrayList of Strings and assign it to a variable
-
+    List<String> stringList = new ArrayList<>();
     // Add multiple strings to the List (OK to do one-by-one)
-
+    stringList.add("Cucumber");
+    stringList.add("Carrot");
+    stringList.add("Pepper");
     // 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
-
+    System.out.println("Joined String: " + String.join(", ", stringList));
     // Check whether two strings are equal
-
+    String anotherWord = "Welcome Friend";
+    System.out.println("Are the Strings equal to each other? " + myWord.equals(anotherWord));
     /*
      * Reminder!
      * 

toRefresh.md

@@ -2,4 +2,5 @@
 
 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.
 
-- 
+- Float Variables
+- Java Classes and instance fields