Proposed changes for Java Derusting

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "jdk",
+            "request": "launch",
+            "name": "Launch Java App"
+        }
+    ]
+}

src/ArrayPractice.java

@@ -1,18 +1,26 @@
+
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
-
+    String[] arrayOf4SizeStrings = {"Home", "Part", "Love", "Mans"};
     // Set the value of the array at each index to be a different String
     // It's OK to do this one-by-one
-
+    arrayOf4SizeStrings[0] = "Love";
+    arrayOf4SizeStrings[1] = "Joys";
+    arrayOf4SizeStrings[2] = "Freedom";
+    arrayOf4SizeStrings[3] = "Labor";
     // Get the value of the array at index 2
-
+    System.out.println(arrayOf4SizeStrings[2]);
     // Get the length of the array
-
+    System.out.println(arrayOf4SizeStrings.length);
     // Iterate over the array using a traditional for loop and print out each item
-
+    for (int i = 0; i < arrayOf4SizeStrings.length; i++){
+      System.out.println(i);
+    }
     // Iterate over the array using a for-each loop and print out each item
-
+    for (String n : arrayOf4SizeStrings){
+      System.out.println(n);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,28 +1,43 @@
+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> theList = new ArrayList<>();
     // Add 3 elements to the list (OK to do one-by-one)
-
+    theList.add("Thinga");
+    theList.add("Thingb");
+    theList.add("Thingc");
     // Print the element at index 1
-
+    System.out.println("\nElement at index 1: "+ theList.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)
-
+    theList.set(1, "Grape");
+    System.out.println("After replacing index 1: " + theList);
     // Insert a new element at index 0 (the length of the list will change)
-
-    // Check whether the list contains a certain string
-
+    theList.add("Thing");
+    // Check whether the list contains a certain string'
+    if (theList.contains("Thing")){
+      System.out.println("Thing detected");
+    }    
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
-
+    int increment = 0;
+    for (String n : theList){
+      System.out.println("Id: " + increment + " | " + n);
+      increment += 1;
+    }
     // Sort the list using the Collections library
-
+    Collections.sort(theList);
     // Iterate over the list using a for-each loop
     // Print each value on a second line
-
+    for (String options : theList) {
+      System.out.println(options);
+    }
     /*
      * Usage tip!
      * 

src/MapPractice.java

@@ -1,29 +1,50 @@
-
+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> userScores = new HashMap<>();
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
-
+    userScores.put("Alice", 2);
+    userScores.put("Bob", 1);
+    userScores.put("Charlie", 3);
     // Get the value associated with a given key in the Map
-
+    userScores.get("Bob");
     // Find the size (number of key/value pairs) of the Map
-
+    System.out.println(userScores.size());
     // Replace the value associated with a given key (the size of the Map shoukld not change)
-
+    userScores.replace("Bob", 7);
     // Check whether the Map contains a given key
-
+    if (userScores.containsKey("Bob")){
+      System.out.println("Contains key");
+    }
+    else {
+      System.out.println("Does not contain key");
+    }
     // Check whether the Map contains a given value
-
+    if (userScores.containsValue("7")) {
+      System.out.println("Does contain 7");
+    }
+    else {
+      System.out.println("Does not contain 7");
+    }
     // Iterate over the keys of the Map, printing each key
-
+    for (String key : userScores.keySet()) {
+      System.out.println(key);
+    }
     // Iterate over the values of the map, printing each value
-
+    for (Integer value : userScores.values()) {
+      System.out.println(value);
+    }
     // Iterate over the entries in the map, printing each key and value
-
+    for (String k : userScores.keySet()){
+      int defOfPair = userScores.get(k);
+      System.out.println(k + " " + defOfPair);
+    }
     /*
      * Usage tip!
      * 

src/NumberPractice.java

@@ -1,25 +1,33 @@
 public class NumberPractice {
   public static void main(String args[]) {
     // Create a float with a negative value and assign it to a variable
-
+    float negative = -1;
+    System.out.println(negative);
     // Create an int with a positive value and assign it to a variable
-
+    int positive= 1;
+    System.out.println(positive);
     // Use the modulo % operator to find the remainder when the int is divided by 3
-
+    int modulo = 1 % 3;
+    System.out.println(modulo);
     // 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 (1 % 2 == 0) {
+      System.out.println("Even");
+    }
+    else{
+      System.out.println("Odd");
+    }
     // Divide the number by another number using integer division
-
+    double divided = 1.0 / 5;
+    System.out.println(divided);
     /*
      * Reminder!
      * 
      * When dividing ints, the result is rounded down.
      * Example: 
-     * 7 / 3 = 2 when performing int division
+     * 7 / 3 = 2 when performing int division`
      */
-
   }
 }

src/Person.java

@@ -4,16 +4,25 @@
  */
 
 public class Person {
+
+    public Person(String jeff, int par) {
+    }
   // 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 NameOfPerson;
+  private int AgeOfPerson;
 
   // Create a constructor that takes the name and age of the person
   // and assigns it to the instance variables
-
+  public void PersonConstructor(String name, int age) {
+    this.NameOfPerson = name;
+    this.AgeOfPerson = age;
+  }
 
   // Create a toString method that gives the name and age of the person
-
+  public String toString() {
+    return NameOfPerson + ": " + AgeOfPerson;
+  }
 
   // Implement the below public instance method "birthYear"
   // There should NOT be any print statement in this method.
@@ -28,26 +37,29 @@ public class Person {
    * @return The year the person was born
    */
   // (create the instance method here)
+  public int birthYear(int currentYear){
+    return currentYear - AgeOfPerson;
+  }
 
 
   public static void main(String[] args) {
     // Create an instance of Person
-
+    Person person1 = new Person("Jeff", 26);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
-
+    Person person2 = new Person("Chelsea", 36);
     // 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
-
+    Person storedPerson = person1;
     // 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 birthdateOfPerson = person1.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+    System.out.println(birthdateOfPerson);
     /**
      * Terminology!
      * 

src/StringPractice.java

@@ -1,26 +1,49 @@
+
+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 this5Chars = "Lovely";
     // Find the length of the string
-
+    System.out.println(this5Chars.length());
     // Concatenate (add) two strings together and reassign the result
+    String thing1 = "Wow";
+    String thing2 = "zers";
 
+    this5Chars = (thing1 + thing2 + "!");
+    System.out.println(this5Chars);
     // Find the value of the character at index 3
-
+    char val3 = this5Chars.charAt(3);
+    System.out.println("Val 3: " + val3);
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
-
+    if (this5Chars.contains("owz")) {
+      System.out.println("Contains owz");
+    }
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for (int i = 0; i < this5Chars.length(); i++) {
+      char character = this5Chars.charAt(i);
+      System.out.println(character);
+    }
     // Create an ArrayList of Strings and assign it to a variable
-
+    List<String> stringList = new ArrayList<>();
     // Add multiple strings to the List (OK to do one-by-one)
-
+    stringList.add("TH");
+    stringList.add("LIFE LIVE LOVE");
+    stringList.add("Live laugh love actually");
     // 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
-
+    System.out.println("Joined String! " + String.join(", " + stringList));
     // Check whether two strings are equal
-
+    String string1 = "Who";
+    String string2 = "Who";
+    if (string1 == string2){
+      System.out.println("Equal");
+    }
+    else {
+      System.out.println("Not equal");
+    }
     /*
      * 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.
 
-- 
+- Adding to lists
+- Constructors / this.[enter] statements
+- Map<> functions