Java Derusting

src/ArrayPractice.java

@@ -1,18 +1,33 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
+    String [] words = 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
+    words[0] = "Diamond";
+    words[1] = "Ruby";
+    words[2] = "Pearl";
+    words[3] = "Emerald";
 
     // Get the value of the array at index 2
+    String valAtTwo = words[2];
 
     // Get the length of the array
+    int wordsLength = words.length;
 
     // Iterate over the array using a traditional for loop and print out each item
+    for(int i = 0; i < words.length; i++)
+    {
+        System.out.println(words[i]);
+    }
+    System.out.println();
 
     // Iterate over the array using a for-each loop and print out each item
-
+    for(String word : words)
+    {
+      System.out.println(word);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,48 @@
+import java.util.ArrayList;
+import java.util.List;
+import java.util.*;
+
 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> wordList= new ArrayList<>();
 
     // Add 3 elements to the list (OK to do one-by-one)
+    wordList.add("Hello");
+    wordList.add("Beautiful");
+    wordList.add("World");
 
     // Print the element at index 1
+    System.out.println(wordList.get(1));
+    System.out.println();
 
     // Replace the element at index 1 with a new value
+    wordList.set(1, "Hi");
+
     // (Do not insert a new value. The length of the list should not change)
 
     // Insert a new element at index 0 (the length of the list will change)
+    wordList.add(0,"Hola");
 
     // Check whether the list contains a certain string
-
+    wordList.contains("World");
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
-
+    for(int i = 0; i < wordList.size(); i++)
+    {
+        System.out.println("Index: " + i + " Value: "+ wordList.get(i));
+    }
+    System.out.println();
     // Sort the list using the Collections library
-
+    Collections.sort(wordList);
     // Iterate over the list using a for-each loop
     // Print each value on a second line
-
+    for(String word : wordList)
+    {
+        System.out.println("Value: " + word + " ");
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,52 @@
-
+import java.util.HashMap;
+import java.util.List;
+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> wordMap = new HashMap <>();
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
+    wordMap.put("Glasgow", 1);
+    wordMap.put("Mexico City", 10);
+    wordMap.put("Madrid", 2);
 
     // Get the value associated with a given key in the Map
+    wordMap.get("Glasgow");
 
     // Find the size (number of key/value pairs) of the Map
+    wordMap.size();
 
     // Replace the value associated with a given key (the size of the Map shoukld not change)
+    wordMap.replace("Mexico City", 20);
 
     // Check whether the Map contains a given key
+    wordMap.containsKey("Madrid");
 
     // Check whether the Map contains a given value
+    wordMap.containsValue(13);
 
     // Iterate over the keys of the Map, printing each key
-
+    for(String key : wordMap.keySet())
+    {
+      System.out.println(key);
+    }
+    System.out.println();
     // Iterate over the values of the map, printing each value
-
+    for(int value : wordMap.values())
+    {
+      System.out.println(value);
+    }
+    System.out.println();
     // Iterate over the entries in the map, printing each key and value
-
+    for(String key : wordMap.keySet())
+    {
+      System.out.println("Key: " + key + " Value: " + wordMap.get(key));
+    }
+
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -21,5 +21,18 @@ public static void main(String args[]) {
      * 7 / 3 = 2 when performing int division
      */
 
+    double negFloat = -1.5;
+    int posInt = 1;
+    int remainder = posInt % 3;
+    if(remainder % 2 == 0)
+    {
+      System.out.println("even");
+    }
+    else
+    {
+      System.out.println("odd");
+    }
+    int intDivision = remainder / 5;
+
   }
 }

src/Person.java

@@ -6,14 +6,33 @@
 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 pName, int pAge)
+  {
+    name = pName;
+    age = pAge;
+  }
 
   // Create a toString method that gives the name and age of the person
+  @Override
+  public String toString()
+  {
+    return "Name: " + name + " Age: " + age;
+  }
 
+  public String getName()
+  {
+    return name;
+  }
+
+  public int getAge()
+  {
+    return age;
+  }
 
   // Implement the below public instance method "birthYear"
   // There should NOT be any print statement in this method.
@@ -28,25 +47,35 @@ 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 person1 = new Person("Ivy", 20);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person person2 = new Person("Kai", 17);
 
     // Print the first person
+    System.out.println(person1);
 
     // Print the second person
+    System.out.println(person2);
 
     // Get the name of the first person and store it in a local variable
+    String pName1 = person1.getName();
 
     // 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 pBirthYear1 = person1.birthYear(2025);
 
     // In a separate statement, print the local variable holding the birth year.
+    System.out.println(pBirthYear1);
 
     /**
      * Terminology!

src/SetPractice.java

@@ -1,18 +1,30 @@
+import java.util.HashSet;
+import java.util.*;
+
 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> stringSet = new HashSet<>();
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    stringSet.add("Sweet");
+    stringSet.add("Salty");
+    stringSet.add("Sour");
 
     // Check whether the Set contains a given String
+    boolean hasSour = stringSet.contains("Sour");
 
     // Remove an element from the Set
+    stringSet.remove("Sour");
 
     // Get the size of the Set
-
+    stringSet.size();
     // Iterate over the elements of the Set, printing each one on a separate line
-
+    for(String s : stringSet)
+    {
+      System.out.println(s);
+    }
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,25 +1,47 @@
+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 fiveChar = "Sprinkles";
 
     // Find the length of the string
+    fiveChar.length();
 
     // Concatenate (add) two strings together and reassign the result
+    fiveChar = fiveChar + "Frosting";
 
     // Find the value of the character at index 3
+    char charAtThree = fiveChar.charAt(3);
+    //System.out.println(charAtThree);
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    boolean hasRink = fiveChar.contains("rink");
+    //System.out.println(hasRink);
 
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for(int i = 0; i < fiveChar.length(); i++)
+    {
+      System.out.println(fiveChar.charAt(i));
+    }
+    System.out.println();
     // Create an ArrayList of Strings and assign it to a variable
+    List<String> wordList = new ArrayList<>();
 
     // Add multiple strings to the List (OK to do one-by-one)
+    wordList.add("Cake");
+    wordList.add("Berries");
+    wordList.add("Candles");
 
     // 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 combinedList = wordList.get(0) + ", " + wordList.get(1) + ", " + wordList.get(2);
+    //System.out.println(combinedList);
 
     // Check whether two strings are equal
+    boolean isEqual = combinedList.equals(fiveChar);
+    //System.out.println(isEqual);
 
     /*
      * Reminder!