Finished Practice PR

src/ArrayPractice.java

@@ -1,22 +1,36 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
+    String[] myArray = 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
 
+    myArray[0] = "A";
+    myArray[1] = "B";
+    myArray[2] = "C";
+    myArray[3] = "D";
+
     // Get the value of the array at index 2
+    System.out.println(myArray[2]);
 
     // Get the length of the array
+    System.out.println(myArray.length);
 
     // Iterate over the array using a traditional for loop and print out each item
+    for(int i = 0; i > myArray.length; i++){
+      System.out.println(myArray[i]);
+    }
 
     // Iterate over the array using a for-each loop and print out each item
+    for(String letter : myArray){
+      System.out.println(letter);
+    }
 
     /*
      * Reminder!
      * 
      * Arrays start at index 0
      */
   }
-}
+}

src/ListPractice.java

@@ -1,28 +1,37 @@
+import java.util.*; // needs to be imported to run, don't know the specifics for collections, so importing utils.
+
 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("A");
+    list.add("B");
+    list.add("C");
     // 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,"D");
     // Insert a new element at index 0 (the length of the list will change)
-
+    list.add(0, "E");
     // Check whether the list contains a certain string
-
+    System.out.println("Contains E?: " + list.contains("E"));
     // 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("Index: " + i + ". Value: " + list.get(i));
+    }
     // Sort the list using the Collections library
-
+    Collections.sort(list);
     // Iterate over the list using a for-each loop
     // Print each value on a second line
-
+    for(String listLetter : list){
+
+      System.out.println("Value: " + listLetter);
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,37 @@
-
+import java.util.*;
 
 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> mapsPractice = new HashMap<>();
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
-
+    mapsPractice.put("hello", 0);
+    mapsPractice.put("neutral", 1);
+    mapsPractice.put("goodbye", 2);
     // Get the value associated with a given key in the Map
-
+    mapsPractice.get("hello");
     // Find the size (number of key/value pairs) of the Map
-
+    mapsPractice.size();
     // Replace the value associated with a given key (the size of the Map shoukld not change)
-
+    mapsPractice.replace("hello", 3);
     // Check whether the Map contains a given key
-
+    mapsPractice.containsKey("goodbye");
     // Check whether the Map contains a given value
-
+    mapsPractice.containsValue(5);
     // Iterate over the keys of the Map, printing each key
-
+    for(String entry : mapsPractice.keySet()){ 
+      System.out.println(entry);
+    }
     // Iterate over the values of the map, printing each value
-
+    for(int entry : mapsPractice.values()){ 
+      System.out.println(entry);
+    }
     // Iterate over the entries in the map, printing each key and value
-
+    for(String entry : mapsPractice.keySet()){ 
+      System.out.println("Key: " + entry + ". Value: " + mapsPractice.get(entry));
+    }
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -1,18 +1,26 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
-
+    float i = -0.1f;
     // Create an int with a positive value and assign it to a variable
-
+    int k = 4;
     // Use the modulo % operator to find the remainder when the int is divided by 3
-
+    int l = k%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(k % 2 == 1){
+      System.out.println("Odd");
+    }
+    else{
+      System.out.println("Even");
+    }
 
     // Divide the number by another number using integer division
-
+    int a = 4;
+    int b = 2;
+    int c = a / b;
     /*
      * Reminder!
      * 

src/Person.java

@@ -3,17 +3,25 @@
  * the Person class.
  */
 
+import java.util.*;
+
 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 = -99;
 
   // Create a constructor that takes the name and age of the person
   // and assigns it to the instance variables
-
+    public Person(String x, int y){
+      name = x;
+      age = y;
+    }
 
   // 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.
@@ -28,26 +36,32 @@ public class Person {
    * @return The year the person was born
    */
   // (create the instance method here)
-
+    public int birthYear(int currentYear){
+      return(currentYear - age);
+    }
+  // Created a method to get name easier.
+    public String getName(){
+      return(name);
+    }
 
   public static void main(String[] args) {
     // Create an instance of Person
-
+    Person jim = new Person("Jim", 45);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
-
+    Person tim = new Person("Tim", 25);
     // Print the first person
-
+    System.out.println(jim);
     // Print the second person
-
+    System.out.println(tim);
     // Get the name of the first person and store it in a local variable
-
+    String grabbedName = jim.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 jimBirthYear = jim.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+    System.out.println(jimBirthYear);
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,18 +1,24 @@
+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> hashSetPractice = new HashSet<String>();
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
-
+    hashSetPractice.add("good morning");
+    hashSetPractice.add("good afternoon");
+    hashSetPractice.add("good night");
     // Check whether the Set contains a given String
-
+    hashSetPractice.contains("good morning");
     // Remove an element from the Set
-
+    hashSetPractice.remove("good night");
     // Get the size of the Set
-
+    hashSetPractice.size();
     // Iterate over the elements of the Set, printing each one on a separate line
-
+    for(String saying : hashSetPractice){
+      System.out.println(saying);
+    }
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,26 +1,38 @@
 public class StringPractice {
   public static void main(String[] args) {
     // Create a string with at least 5 characters and assign it to a variable
-
+    String a = "ABCDE";
     // Find the length of the string
-
+    a.length();
     // Concatenate (add) two strings together and reassign the result
-
+    String b = "FGHIJ";
+    String c = a + b;
     // Find the value of the character at index 3
-
+    c.charAt(3);
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
-
+    c.contains("BCD");
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for(int i = 0; i < c.length(); i++){
+      System.out.println(c.charAt(i));
+    }
     // Create an ArrayList of Strings and assign it to a variable
-
+    String[] myArray = new String[4];
     // Add multiple strings to the List (OK to do one-by-one)
-
+    myArray[0] = "A";
+    myArray[1] = "B";
+    myArray[2] = "C";
+    myArray[3] = "D";
     // 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 combined = String.join(", ", myArray);
     // Check whether two strings are equal
-
+    String d = "ABCDE";
+    if(a.equals(d)){
+      System.out.println("strings match up.");
+    }
+    else{
+      System.out.println("strings don't match up.");
+    }
     /*
      * Reminder!
      *