derusting complete

src/ArrayPractice.java

@@ -1,17 +1,39 @@
+import java.util.Arrays; 
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
+    String[] strArray = {"red", "orange", "yellow", "green"};
+    System.out.println(Arrays.toString(strArray));
 
     // Set the value of the array at each index to be a different String
     // It's OK to do this one-by-one
+    strArray[0] = "blue";
+    strArray[1] = "purple";
+    strArray[2] = "red";
+    strArray[3] = "orange";
+    System.out.println(Arrays.toString(strArray));
 
     // Get the value of the array at index 2
+    System.out.println("The value at index 2 is " + strArray[2]); // expect "The value at index 2 is red"
 
     // Get the length of the array
+    System.out.print("The array length is ");
+    System.out.print(strArray.length);
+    // expects "The array length is 4"
+    System.out.println();
+
 
     // Iterate over the array using a traditional for loop and print out each item
+    System.out.println();
+    for (int i = 0; i < strArray.length; i++) {
+      System.out.println(strArray[i]);
+    }
 
     // Iterate over the array using a for-each loop and print out each item
+    System.out.println();
+    for (String color: strArray) {
+      System.out.println(color);
+    }
 
     /*
      * Reminder!

src/ListPractice.java

@@ -1,27 +1,60 @@
+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> stringList = new ArrayList<String>();
+    System.out.println(stringList);
 
     // Add 3 elements to the list (OK to do one-by-one)
+    stringList.add("banana");
+    stringList.add("mango");
+    stringList.add("lemon");
+    System.out.println(stringList);
 
     // Print the element at index 1
+    System.out.println(stringList.get(1)); // should print "mango"
 
     // Replace the element at index 1 with a new value
     // (Do not insert a new value. The length of the list should not change)
+    stringList.set(1, "kiwi");
+    System.out.println(stringList); // should print "[banana, kiwi, lemon]"
 
     // Insert a new element at index 0 (the length of the list will change)
+    stringList.add(0, "strawberry");
+    System.out.println(stringList); // should print "[strawberry, banana, kiwi, lemon]"
 
     // Check whether the list contains a certain string
+    if (stringList.contains("banana")) {
+        System.out.println("That's bananas!"); // expected output
+    } else {
+      System.out.println("No bananas here.");
+    }
 
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
+    System.out.println();
+    for (int i = 0; i < stringList.size(); i++) {
+      String fruit = stringList.get(i);
+      System.out.print(i);
+      System.out.print(" " + fruit);
+      System.out.println();
+    }
 
     // Sort the list using the Collections library
+    Collections.sort(stringList);
+    System.out.println(stringList); // should print "[banana, kiwi, lemon, strawberry]"
+    System.out.println();
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for (String fruit : stringList) {
+      System.out.println(fruit);
+    };
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,28 +1,62 @@
-
+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> simpsons = new HashMap<String, Integer>();
+    System.out.println(simpsons);
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
+    simpsons.put("Homer", 38);
+    simpsons.put("Marge", 36);
+    simpsons.put("Bart", 10);
+    simpsons.put("Lisa", 8);
+    simpsons.put("Maggie", 1);
+    System.out.println(simpsons);
 
     // Get the value associated with a given key in the Map
+    System.out.println(simpsons.get("Maggie")); // expect 1
 
     // Find the size (number of key/value pairs) of the Map
+    System.out.print("The map size is ");
+    System.out.println(simpsons.size());
 
     // Replace the value associated with a given key (the size of the Map shoukld not change)
+    System.out.print("It's Lisa's birthday! Now she is: ");
+    simpsons.put("Lisa", simpsons.get("Lisa") + 1);
+    System.out.println(simpsons.get("Lisa"));
 
     // Check whether the Map contains a given key
+    if (simpsons.containsKey("Homer")) {
+      System.out.println("Homer is a Simpson.");
+    } else {
+      System.out.println("Where did Homer go??");
+    }
 
     // Check whether the Map contains a given value
+    if (simpsons.containsValue(42)) {
+      System.out.println("42 is a cool age!");
+    } else {
+      System.out.println("None of the Simpsons are 42.");
+    }
 
     // Iterate over the keys of the Map, printing each key
+    for (String name : simpsons.keySet()) {
+      System.out.println(name);
+    }
 
     // Iterate over the values of the map, printing each value
+    for (Integer age : simpsons.values()) {
+      System.out.println(age);
+    }
 
     // Iterate over the entries in the map, printing each key and value
+    for (Map.Entry<String,Integer> person : simpsons.entrySet()) {
+      System.out.println(person.getKey() + " is " + person.getValue() + " years old.");
+    }
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -1,17 +1,30 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
+    float negativeFloat = -0.12345f;
+    System.out.println(negativeFloat);
 
     // Create an int with a positive value and assign it to a variable
+    int positiveInteger = 42;
+    System.out.println(positiveInteger);
 
     // Use the modulo % operator to find the remainder when the int is divided by 3
+    int remainder = positiveInteger % 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 (remainder % 2 == 0) {
+      System.out.println("Even");
+    } else if (remainder % 2 != 0) {
+      System.out.println("Odd");
+    };
 
     // Divide the number by another number using integer division
+    int dividend = remainder / 2;
+    System.out.println(dividend);
 
     /*
      * Reminder!

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 + " " + age;
+  }
 
   // Implement the below public instance method "birthYear"
   // There should NOT be any print statement in this method.
@@ -28,25 +34,35 @@ 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 rebecca = new Person("Rebecca", 31);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person ari = new Person("Ari", 1);
 
     // Print the first person
+    System.out.println(rebecca.toString());
 
     // Print the second person
+    System.out.println(ari.toString());
 
     // Get the name of the first person and store it in a local variable
+    String myFirstName = rebecca.name;
+    System.out.println("My first name is " + myFirstName);
 
     // 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 = rebecca.birthYear(2025);
+
     // In a separate statement, print the local variable holding the birth year.
+    System.out.println("If my birthday had already happened this year, my birth year would be " + birthYear);
 
     /**
      * Terminology!

src/SetPractice.java

@@ -1,17 +1,39 @@
+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> movies = new HashSet<>();
+    System.out.println(movies);
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    movies.add("Anna and the Apocalypse");
+    movies.add("Wicked");
+    movies.add("Lilo and Stitch");
+    movies.add("Memento");
+    System.out.println(movies);
 
     // Check whether the Set contains a given String
+    if (movies.contains("The Matrix")){
+      System.out.println("INSERT QUOTE FROM THE MATRIX HERE");
+    } else {
+      System.out.println("You should add 'The Matrix' to this movie collection!");
+    }
 
     // Remove an element from the Set
+    movies.remove("Wicked");
+    System.out.println(movies);
 
     // Get the size of the Set
+    System.out.print("The size of this set is ");
+    System.out.println(movies.size());
 
     // Iterate over the elements of the Set, printing each one on a separate line
+    for (String movie : movies) {
+      System.out.println(movie);
+    }
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,25 +1,66 @@
+import java.util.ArrayList;
+
 public class StringPractice {
   public static void main(String[] args) {
     // Create a string with at least 5 characters and assign it to a variable
+    String greeting = "Hello";
+    System.out.println(greeting);
 
     // Find the length of the string
+    int length = greeting.length();
+    System.out.println(length);
 
     // Concatenate (add) two strings together and reassign the result
+    String name = "Rebecca";
+    String nameGreeting = greeting + ", " + name + "!";
+    System.out.println(nameGreeting);
 
     // Find the value of the character at index 3
+    System.out.println(nameGreeting.charAt(3)); // expect 'l'
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    boolean hasABitOfCalifornia = nameGreeting.contains("ca");
+
+    if (hasABitOfCalifornia) {
+      System.out.println("There's a little bit of California in that! ('ca')"); // expected output
+    } else {
+      System.out.println("No California here!");
+    }
 
     // Iterate over the characters of the string, printing each one on a separate line
+    System.out.println();
+    for (int i = 0; i < nameGreeting.length(); i++) {
+      System.out.println(nameGreeting.charAt(i));
+    }
 
     // Create an ArrayList of Strings and assign it to a variable
+    ArrayList<String> zoo = new ArrayList<>();
+    System.out.println(zoo);
 
     // Add multiple strings to the List (OK to do one-by-one)
+    zoo.add("zebra");
+    zoo.add("giraffe");
+    zoo.add("penguin");
+    zoo.add("tiger");
+    System.out.println(zoo);
 
     // 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 listOfAnimals = zoo.toString();
+    listOfAnimals = listOfAnimals.substring(1, listOfAnimals.length() - 1);
+    System.out.println(listOfAnimals);
+
 
     // Check whether two strings are equal
+    String string1 = "apples";
+    String string2 = "apples";
+    String string3 = "oranges";
+
+    System.out.println(compareTwo(string1, string2));
+    System.out.println(compareTwo(string1, string3));
+
+
+
 
     /*
      * Reminder!
@@ -29,4 +70,16 @@ public static void main(String[] args) {
      * We use == when comparing primitives (e.g. int or char).
      */
   }
+
+  public static String compareTwo (String a, String b) {
+    String compared = "";
+    if (a.contentEquals(b)) {
+        compared = "Comparing apples to apples!";
+      } else {
+        compared = "Not comparing apples to apples!";
+      }
+      return compared;
+  }
 }
+
+