Completed assignment Java Derusting

src/ArrayPractice.java

@@ -1,18 +1,30 @@
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
-
+    String[] shoppingList = 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
 
+    shoppingList[0] = "Bread";
+    shoppingList[1] = "Milk";
+    shoppingList[2] = "Cheese";
+    shoppingList[3] = "Banana";
+
     // Get the value of the array at index 2
+    System.out.println(shoppingList[2]);
 
     // Get the length of the array
 
-    // Iterate over the array using a traditional for loop and print out each item
+    System.out.println("Length of array: " + shoppingList.length);
 
+    // Iterate over the array using a traditional for loop and print out each item
+    for(int i = 0; i < shoppingList.length; i++){
+      System.out.println("shoppingList[" + i + "] = " + shoppingList[i]);
+    }
     // Iterate over the array using a for-each loop and print out each item
-
+    for(String str: shoppingList){
+      System.out.println(str);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,46 @@
+import java.util.ArrayList;
+import java.util.Collections;
 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> myList = new ArrayList<>(); 
 
     // Add 3 elements to the list (OK to do one-by-one)
-
+      myList.add("Apple");
+      myList.add("Banana");
+      myList.add("Grapes");
     // Print the element at index 1
+      System.out.println(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,"Blueberry");
 
     // Insert a new element at index 0 (the length of the list will change)
+      myList.add(0,"Raspberry");
 
     // Check whether the list contains a certain string
-
+      System.out.println("Does myList contain Pear? " + myList.contains("Pear"));
     // 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("myList index " + i + ": " + myList.get(i));
+    }
+
     // Sort the list using the Collections library
+    Collections.sort(myList);
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
 
+    for (String str : myList) {
+      System.out.println(str);
+    }
+
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,28 +1,44 @@
-
+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> myHashMap = new HashMap<>();
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
+    myHashMap.put("Six", 3);
+    myHashMap.put("Three", 5);
+    myHashMap.put("Four", 4);
 
     // Get the value associated with a given key in the Map
-
+    myHashMap.get("Six");
     // Find the size (number of key/value pairs) of the Map
-
+    System.out.println("Size of hashmap: " + myHashMap.size());
     // Replace the value associated with a given key (the size of the Map shoukld not change)
 
+       myHashMap.put("Six", 6);
     // Check whether the Map contains a given key
+      System.out.println("Does myHashmap containsKey Four? " + myHashMap.containsKey("Four"));
 
     // Check whether the Map contains a given value
+        System.out.println("Does myHashmap containsValue 9 " + myHashMap.containsValue(9));
 
-    // Iterate over the keys of the Map, printing each key
 
+    // Iterate over the keys of the Map, printing each key
+    for(String s: myHashMap.keySet()){
+      System.out.println("Key: " + s);
+    }
     // Iterate over the values of the map, printing each value
+    for(int i: myHashMap.values()){
+      System.out.println("Value: " + i);
+    }
 
     // Iterate over the entries in the map, printing each key and value
+    for(String s: myHashMap.keySet()){
+      System.out.println("Key: " + s + ", Value: " + myHashMap.get(s));
+    }
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -1,16 +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 myFloat = -1.2f;
+    System.out.println("my float: " + myFloat);
     // Create an int with a positive value and assign it to a variable
-
+    int number = 20;
+    System.out.println("number: " + number);
     // Use the modulo % operator to find the remainder when the int is divided by 3
+    int remainder = number % 3;
+    System.out.println("20 % 3 = " +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(number % 2 == 0){
+      System.out.println(number + " is even!");
+    }else{
+      System.out.println(number + " is odd!");
+    }
+
     // Divide the number by another number using integer division
 
     /*
@@ -21,5 +31,8 @@ public static void main(String args[]) {
      * 7 / 3 = 2 when performing int division
      */
 
+     int solution = number / 4;
+     System.out.println(number + " / 4 = " + solution);
+
   }
 }

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
-
+  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.
@@ -29,25 +35,42 @@ public class Person {
    */
   // (create the instance method here)
 
+  public int birthYear(int currentYear){
+    return currentYear - age;
+  }
+
+  public String getName(){
+      return name;
+  }
+
 
   public static void main(String[] args) {
     // Create an instance of Person
+    Person person1 = new Person("Leo", 20);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person person2 = new Person("Joshua", 40);
 
     // Print the first person
 
-    // Print the second 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 person2Name = person2.getName();
+    System.out.println(person2Name);
     // 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 person1Age = person1.birthYear(2025);
+
     // In a separate statement, print the local variable holding the birth year.
 
+    System.out.println(person1Age);
+
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,17 +1,27 @@
+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> fruits = new HashSet<>();
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
-
+    fruits.add("Kiwi");
+    fruits.add("Blackberry");
+    fruits.add("Tomato");
     // Check whether the Set contains a given String
 
+    System.out.println("Does fruit set contain Banana?" + fruits.contains("Banana"));
     // Remove an element from the Set
 
+    fruits.remove("kiwi");
     // Get the size of the Set
-
+    int sizeOfSet = fruits.size();
+    System.out.println(sizeOfSet);
     // Iterate over the elements of the Set, printing each one on a separate line
+    for (String fruit : fruits) {
+      System.out.println(fruit);
+    }
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,26 +1,50 @@
+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 fruit = "banana";
 
     // Find the length of the string
+    int fruitLength = fruit.length();
+    System.out.println(fruitLength);
 
     // Concatenate (add) two strings together and reassign the result
+    String drink = "milk";
+    String result = fruit + drink;
+    System.out.println(result);
 
     // Find the value of the character at index 3
+    String letter = result.substring(3,4);
+    System.out.println(letter);
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    System.out.println("Does result have milk? " + result.contains("milk"));
 
     // Iterate over the characters of the string, printing each one on a separate line
+    for(char c : result.toCharArray()){
+      System.out.println(c);
+    }
 
     // Create an ArrayList of Strings and assign it to a variable
+    ArrayList<String> myList = new ArrayList<String>();
+
 
     // Add multiple strings to the List (OK to do one-by-one)
+    myList.add("Leo");
+myList.add("Will");
+myList.add("Joshua");
+myList.add("Jadon");
+
 
     // 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 combinedString = String.join(",", myList);
 
+    System.out.println(combinedString);
     // Check whether two strings are equal
-
+    System.err.println("Does Leo equal to Will? " + "Leo".equals("Will"));
+
     /*
      * Reminder!
      * 

toRefresh.md

@@ -2,4 +2,6 @@
 
 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.
 
+
+
 -