Java derusting-ConnorH

README.md

@@ -25,3 +25,8 @@ Most of these taks should be easy, but there will likely be some that ask you to
 Make a Pull Request (PR) against the original repository. Copy the link into Canvas to submit.
 
 
+## What i can work on:
+
+1. For loops 
+2. Arrays
+3. Built in methods

src/ArrayPractice.java

@@ -1,18 +1,32 @@
+import java.util.Arrays;
+
 public class ArrayPractice {
   public static void main(String[] args) {
     // Create an array of Strings of size 4
+    String[] ray = {"one", "two", "three", "four"};
+    System.out.println(Arrays.toString(ray) + '\n');
 
     // Set the value of the array at each index to be a different String
     // It's OK to do this one-by-one
-
+    ray[0]= "1";
+    ray[1]= "2"; 
+    ray[2]= "3";
+    ray[3]= "4";
+    System.out.println(Arrays.toString(ray) + "\n");
     // Get the value of the array at index 2
+    System.out.println(ray[2] + "\n");
 
     // Get the length of the array
-
+    System.out.println(ray.length + "\n");
     // Iterate over the array using a traditional for loop and print out each item
-
+    for(int i = 0; i < ray.length; i++){
+        System.out.println(ray[i]);
+    }
+    System.out.println("\n");
     // Iterate over the array using a for-each loop and print out each item
-
+    for (String item: ray){
+      System.out.println(item);
+    }
     /*
      * Reminder!
      * 

src/ListPractice.java

@@ -1,27 +1,53 @@
+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("First");
+    list.add("Second");
+    list.add("Third");
+    System.out.println(list + "\n");
+
 
     // Print the element at index 1
+    System.out.println(list.get(1) + "\n");
 
     // 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,"Replaced");
+    System.out.println(list + "\n");
 
     // Insert a new element at index 0 (the length of the list will change)
+    list.add(0, "Added");
+    System.out.println(list + "\n");
 
     // Check whether the list contains a certain string
+    System.out.println(list.contains("Third") + "\n");
 
     // 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(i + ": " + list.get(i));
+    }
 
     // Sort the list using the Collections library
+    Collections.sort(list);
+    System.out.println("\n" + list + "\n");
+
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for(String item : list){
+      System.out.println(item + "\n");
+    }
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,28 +1,48 @@
-
+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> map = new HashMap<>();
+
 
     // Put 3 different key/value pairs in the Map
     // (it's OK to do this one-by-one)
+    map.put("Tacos", 5);
+    map.put("Burgers", 8);
+    map.put("Cheesecake", 10);
+    System.out.println(map + "\n");
 
     // Get the value associated with a given key in the Map
+    System.out.println(map.get("Tacos") + '\n');
 
     // Find the size (number of key/value pairs) of the Map
+    System.out.println(map.size() + "\n");
 
     // Replace the value associated with a given key (the size of the Map shoukld not change)
+     map.replace("Tacos", 5, 7);
+    System.out.println(map + "\n");
 
     // Check whether the Map contains a given key
+    System.out.println(map.containsKey("Tacos") + "\n");
 
     // Check whether the Map contains a given value
+     System.out.println(map.containsValue(9) + "\n");
 
     // Iterate over the keys of the Map, printing each key
-
+    for(String key : map.keySet()){
+      System.out.println(key);
+    }
+    System.out.println("\n");
     // Iterate over the values of the map, printing each value
+    for(int value : map.values()){
+      System.out.println(value);
+    }
+    System.out.println("\n");
 
     // Iterate over the entries in the map, printing each key and value
+    map.forEach((key, value) -> {System.out.println(key + ", " + value);});
 
     /*
      * Usage tip!

src/NumberPractice.java

@@ -21,5 +21,24 @@ public static void main(String args[]) {
      * 7 / 3 = 2 when performing int division
      */
 
+     float neg = -7;
+     System.out.println(neg);
+     int num = 8;
+     System.out.println(num);
+     System.out.println(num / 3 % 3);
+
+     int even = 10;
+     if (even % 2 == 0){
+      System.out.println("This number is even: " + even);
+     };
+
+     int n = 5;
+     if (n % 2 == 0){
+      System.out.println("This number is even: " + n);
+     }else{
+      System.out.println("This number is odd: " + n);
+     };
+
+     System.out.println(n / 2);
   }
 }

src/Person.java

@@ -6,13 +6,25 @@
 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 = "Tom";
+  private int age = 32;
+
+
 
 
   // 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 "This person's name is " + name + " and their age is " + age;
+  }
 
 
   // Implement the below public instance method "birthYear"
@@ -28,26 +40,31 @@ 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 tom = new Person("Tom", 32);
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person kari = new Person("Kari", 31);
 
     // Print the first person
-
+    System.out.println(tom);
     // Print the second person
-
+    System.out.println(kari);
     // Get the name of the first person and store it in a local variable
+    String newName = tom.name;
+    System.out.println(newName);
 
     // 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 birthYear =  tom.birthYear(2025);
     // In a separate statement, print the local variable holding the birth year.
-
+    System.out.println(birthYear);
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,17 +1,36 @@
+import java.util.HashSet;
+import java.util.Set;
+
 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> hs = new HashSet<>();
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    hs.add("green");
+    hs.add("blue");
+    hs.add("red");
+    hs.add("yellow");
+    hs.add("pink");
+
+    System.out.println(hs +"\n");
 
     // Check whether the Set contains a given String
+    System.out.println(hs.contains("red") + "\n");
 
     // Remove an element from the Set
+    hs.remove("pink");
+    System.out.println(hs + "\n");
 
     // Get the size of the Set
+    System.out.println(hs.size() + "\n");
 
     // Iterate over the elements of the Set, printing each one on a separate line
+    for(String item : hs){
+      System.out.println(item);
+    }
+    System.out.println("\n");
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,25 +1,48 @@
+import java.util.ArrayList;
+// import java.util.Arrays;
+
 public class StringPractice {
   public static void main(String[] args) {
     // Create a string with at least 5 characters and assign it to a variable
-
+    String word = "Connor";
+    System.out.println(word + "\n");
     // Find the length of the string
-
+    System.out.println(word.length() + "\n");
     // Concatenate (add) two strings together and reassign the result
-
+    String fName = "Connor";
+    String lName = "Hughes";
+    String fullName = fName + " " + lName;
+    System.out.println(fullName + "\n");
     // Find the value of the character at index 3
+    System.out.println(word.charAt(3) + "\n");
 
     // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    System.out.println(word.contains("a") + "\n");
 
     // Iterate over the characters of the string, printing each one on a separate line
-
+    for(int i =0; i < word.length(); i++){
+      System.out.println(word.charAt(i));
+    }
+    System.out.println("\n");
     // Create an ArrayList of Strings and assign it to a variable
-
+    ArrayList<String> ray = new ArrayList<>();
     // Add multiple strings to the List (OK to do one-by-one)
+    ray.add("car");
+    ray.add("dog");
+    ray.add("cat");
+    ray.add("red");
+    ray.add("blue");
+    System.out.println(ray + "\n");
 
     // 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 concat = String.join(", ", ray);
+    System.out.println(concat + "\n");
 
     // Check whether two strings are equal
+    String one = "racecar";
+    String two = "Truck";
+    System.out.println(one.equals(two));
 
     /*
      * Reminder!