Finished Derusting project

src/ArrayPractice.java

@@ -1,18 +1,27 @@
+
+
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
-
+  String[] arr = 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
-
+  arr[0]="Donut";
+  arr[1]="Cake";
+  arr[2]="Cookie";
+  arr[3]="Icecream";
     // Get the value of the array at index 2
-
+  String valueAtIndex = arr[2];
     // Get the length of the array
-
+  int[] length = new int[4];
     // Iterate over the array using a traditional for loop and print out each item
-
+   for (int i = 0; i < arr.length; i++){
+    System.out.println(i + " : " + arr[i]);
+   }
     // Iterate over the array using a for-each loop and print out each item
-
+   for (String item : arr){
+    System.out.println(item);
+   }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,45 @@
+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> list = new ArrayList<>();
     // Add 3 elements to the list (OK to do one-by-one)
-
+  list.add("Beans");
+  list.add("Pineapple");
+  list.add("onion");
     // Print the element at index 1
-
+  list.get(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, "Orange");
     // Insert a new element at index 0 (the length of the list will change)
-
+  list.add(0, "apple");
     // Check whether the list contains a certain string
-
+    if(list.contains("onion")) {
+      System.out.println("Found");
+    } else {
+      System.out.println("Not found");
+    }
     // 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 i : list){
+    System.out.println();
+    System.out.println(i);
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,37 @@
-
+import java.util.HashMap;
 
 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
-
+  HashMap<String, Integer> people = new HashMap<String, Integer>();
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
-
+  people.put("John", 52);
+  people.put("Sarah", 43);
+  people.put("Charles", 23);
     // Get the value associated with a given key in the Map
-
+  people.get("Charles");
     // Find the size (number of key/value pairs) of the Map
-
+  people.size();
     // Replace the value associated with a given key (the size of the Map shoukld not change)
-
+  people.replace("john", 56);
     // Check whether the Map contains a given key
-
+  people.containsKey("sarah");
     // Check whether the Map contains a given value
-
+  people.containsValue("43");
     // Iterate over the keys of the Map, printing each key
-
+  for (String key : people.keySet()){
+    System.out.println(key);
+  }
     // Iterate over the values of the map, printing each value
-
+    for (Integer value: people.values()) {
+      System.out.println(value);
+    }
     // Iterate over the entries in the map, printing each key and value
-
+    for (String i : people.keySet()) {
+      System.out.println("key: " + i + " value: " + people.get(i));
+    }
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -1,18 +1,32 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
+    float f = -1f;
+    System.out.println(f);
 
     // Create an int with a positive value and assign it to a variable
+    int num = 5;
+    System.out.println(num);
 
     // Use the modulo % operator to find the remainder when the int is divided by 3
+    int remainder = num % 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.
-
+    int number = 6;
+    if (number % 2 == 0) {
+      System.out.println(number + " is even");
+      // if the number is odd.
+    } else {
+      System.out.println(number + "is odd");
+    }
+
     // Divide the number by another number using integer division
-
+    int x = 8;
+    int y = 4;
+    System.out.println(x/y);
     /*
      * 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: " + name + ", Age: " + age;
+ }
 
   // Implement the below public instance method "birthYear"
   // There should NOT be any print statement in this method.
@@ -28,26 +34,29 @@ 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 person = new Person("Qin Bao", 32);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
-
+  Person person2 = new Person("Yellow Yao", 24);
     // Print the first person
-
+  System.out.println(person);
     // Print the second person
-
+System.out.println(person2);
     // Get the name of the first person and store it in a local variable
-
+  String firstPersonName = person.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 = person.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+  System.out.println("First Person's Name: " + firstPersonName);
+  System.out.println("First Person's birthyear: " + firstPersonBirthYear);
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,18 +1,25 @@
+import java.util.HashSet;
+
 public class SetPractice {
   public static void main(String[] args) {
     // Create a HashSet of Strings and assign it to a variable of type Set
-
+    HashSet<String> helicopters = new HashSet<String>();
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
-
+    helicopters.add("Huey");
+    helicopters.add("Mi24");
+    helicopters.add("cobra");
     // Check whether the Set contains a given String
-
+    System.out.println("Does the set contain 'Mi24' ?" + helicopters.contains("Mi24"));
     // Remove an element from the Set
-
+    helicopters.remove("Huey");
     // Get the size of the Set
-
+    int size = helicopters.size();
+    System.out.println("The set size is: " + size);
     // Iterate over the elements of the Set, printing each one on a separate line
-
+    for (String helicopter : helicopters){
+      System.out.println(helicopter);
+    }
     /*
      * Warning!
      * 

src/StringPractice.java

@@ -1,26 +1,48 @@
+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 txt = "Hotdogs";
     // Find the length of the string
-
+  System.out.println(txt.length());
     // Concatenate (add) two strings together and reassign the result
-
+  String toppingOne = "Stuffed";
+  String toppingTwo = "Crust";
+  toppingOne = toppingOne + toppingTwo;
+  System.out.println(toppingOne);
     // Find the value of the character at index 3
-
+  String findme = "Please find me here";
+  System.out.println(findme.indexOf("find"));
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
-
+  String substring = "find";
+  if(findme.contains(substring)) {
+    System.out.println(substring);
+  } else {
+    System.out.println("There are no substring in " + substring );
+  }
     // Iterate over the characters of the string, printing each one on a separate line
-
+  for (int i = 0; i < findme.length(); i++){
+    char ch = findme.charAt(i);
+    System.out.println(ch);
+  }
     // Create an ArrayList of Strings and assign it to a variable
-
+    ArrayList<String> bedroom = new ArrayList<String>();
+
     // Add multiple strings to the List (OK to do one-by-one)
-
+    bedroom.add("bed");
+    bedroom.add("table");
+    bedroom.add("lamp");
     // 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 joinedString = String.join(",", bedroom);
+    System.out.println(joinedString);
     // Check whether two strings are equal
-
+   String f1 ="football";
+   String f2 = "soccerball";
+   String f3 ="football";
+   System.out.println(f1.equals(f2));
+   System.out.println(f1.equals(f3));
     /*
      * Reminder!
      * 

toRefresh.md

@@ -2,4 +2,4 @@
 
 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.
 
-- 
+- I need to work on specfically Arrays as I had a hard time with that practice. I seem to do just fine as I find it easier to do ArrayLists.