Java Derusting assignment done

src/ArrayPractice.java

@@ -1,17 +1,38 @@
+import java.util.Arrays;
 public class ArrayPractice {
   public static void main(String[] args) {
-    // Create an array of Strings of size 4
+     // Create an array of Strings of size 4
+   String[] arr = {"bahram", "Ibrahim", "Kamran", "Asif"};
+      System.out.println("First Array " + Arrays.toString(arr));
 
     // Set the value of the array at each index to be a different String
-    // It's OK to do this one-by-one
-
+   // It's OK to do this one-by-one
+   String[] newArray = new String[4];
+
+    newArray[0] = "Ibrahim";
+    newArray[1] = "Bahram";
+    newArray[2] = "Kamran";
+    newArray[3] = "Asif";
+    System.out.println("Second Array" + Arrays.toString(newArray));
     // Get the value of the array at index 2
+    System.out.println("Second Value " + newArray[1]);
 
     // Get the length of the array
+    System.out.println("Length of Array " + newArray.length);
 
     // Iterate over the array using a traditional for loop and print out each item
+    System.out.println("After for Loop " );
+    for(int i = 0; i < 4 ; i++){
+      System.out.println(newArray[i]);
+    }
 
     // Iterate over the array using a for-each loop and print out each item
+    System.out.println("After for each Loop ");
+    for(String names: newArray){
+      System.out.println(names);
+    }
+
+
 
     /*
      * Reminder!

src/ListPractice.java

@@ -1,27 +1,55 @@
+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> namesList = new ArrayList<>();
 
     // Add 3 elements to the list (OK to do one-by-one)
-
+    namesList.add("Bahram");
+    namesList.add("Ibrahim");
+    namesList.add("Kamran");
+    namesList.add("Asif");
+    System.out.println(namesList);
     // Print the element at index 1
+    System.out.println(namesList.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)
+    namesList.set(1, "Abdul");
+    System.out.println(namesList);
 
     // Insert a new element at index 0 (the length of the list will change)
+    namesList.add("Ikram");
+    System.out.println(namesList);
 
     // Check whether the list contains a certain string
+    String searchName = "Bahra";
+    if(namesList.contains(searchName)){
+      System.out.println("The nameList have " + searchName );
+    }else{
+      System.out.println(searchName + " is not on the List");
+    }
 
     // Iterate over the list using a traditional for-loop.
     // Print each index and value on a separate line
+    for(int i = 0; i < namesList.size(); i++){
+      System.out.println("Index " + i + ": " + namesList.get(i)); 
+    }
 
     // Sort the list using the Collections library
+    Collections.sort(namesList);
+    System.out.println("After the list is sorted " + namesList);
 
     // Iterate over the list using a for-each loop
     // Print each value on a second line
+    for(String newNamesList: namesList){
+      System.out.println();
+      System.out.println(newNamesList);
+    }
 
     /*
      * Usage tip!

src/MapPractice.java

@@ -1,30 +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
-
-    // Put 3 different key/value pairs in the Map
-    // (it's OK to do this one-by-one)
-
-    // Get the value associated with a given key in the Map
-
-    // Find the size (number of key/value pairs) of the Map
-
-    // Replace the value associated with a given key (the size of the Map shoukld not change)
-
-    // Check whether the Map contains a given key
-
-    // Check whether the Map contains a given value
-
-    // Iterate over the keys of the Map, printing each key
-
-    // Iterate over the values of the map, printing each value
-
-    // Iterate over the entries in the map, printing each key and value
-
-    /*
+    // Create a HashMap with String keys and Integer values
+    Map<String, Integer> map = new HashMap<>();
+
+    // Add 3 key/value pairs to the Map
+    map.put("Alice", 25);
+    map.put("Bob", 30);
+    map.put("Charlie", 35);
+
+    // Get the value for the key "Alice"
+    System.out.println("Alice's age: " + map.get("Alice"));
+
+    // Find the size of the Map
+    System.out.println("Number of entries in the Map: " + map.size());
+
+    // Replace Bob's age
+    map.put("Bob", 40);
+    System.out.println("Bob's new age: " + map.get("Bob"));
+
+    // Check if the Map contains the key "Charlie"
+    System.out.println("Map contains Charlie: " + map.containsKey("Charlie"));
+
+    // Check if the Map contains the value 40
+    System.out.println("Map contains age 40: " + map.containsValue(40));
+
+    // Print all keys
+    System.out.println("Keys in the Map:");
+    for (String key : map.keySet()) {
+      System.out.println(key);
+    }
+
+    // Print all values
+    System.out.println("Values in the Map:");
+    for (Integer value : map.values()) {
+      System.out.println(value);
+    }
+
+    // Print all key/value pairs
+    System.out.println("Entries in the Map:");
+    for (Map.Entry<String, Integer> entry : map.entrySet()) {
+      System.out.println("Key: " + entry.getKey() + ", Value: " + entry.getValue());
+    }
+   /*
      * Usage tip!
      * 
      * Maps are great when you want a specific key to value mapping.
@@ -40,4 +60,4 @@ public static void main(String[] args) {
      * and you don't care about any ordering.
      */
   }
-}
+}

src/NumberPractice.java

@@ -1,17 +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 negativeFloat = -5.5f;
 
     // Create an int with a positive value and assign it to a variable
+    int positiveInt = 42;
 
     // Use the modulo % operator to find the remainder when the int is divided by 3
+    int remainder = positiveInt % 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 (positiveInt % 2 == 0) {
+      System.out.println("Even");
+    } else {
+      System.out.println("Odd");
+    }
 
     // Divide the number by another number using integer division
+    int quotient = positiveInt / 7;
 
     /*
      * Reminder!
@@ -20,6 +29,5 @@ public static void main(String args[]) {
      * Example: 
      * 7 / 3 = 2 when performing int division
      */
-
   }
 }

src/Person.java

@@ -2,18 +2,25 @@
  * In this file you will follow the comments' instructions to complete
  * the Person class.
  */
-
 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;
 
+  // Declare a private int instance variable for the age of the person
+  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
-
+  @Override
+  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.
@@ -27,27 +34,33 @@ public class Person {
    * @param currentYear an int for the current year
    * @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 person1 = new Person("Bahram", 25);
 
     // Create another instance of Person with a different name and age and
     // assign it to a different variable
+    Person person2 = new Person("Ibrahim", 30);
 
     // 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
+    String firstName = person1.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.
-
-    // In a separate statement, print the local variable holding the birth year.
+    // and store it in a local variable. Input the actual current year (e.g., 2025)
+    int firstPersonBirthYear = person1.birthYear(2025);
 
+    // In a separate statement, print the local variable holding the birth year
+    System.out.println("Birth Year of " + firstName + ": " + firstPersonBirthYear);
     /**
      * Terminology!
      * 

src/SetPractice.java

@@ -1,17 +1,32 @@
+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> stringSet = new HashSet<>();
 
     // Add 3 elements to the set
     // (It's OK to do it one-by-one)
+    stringSet.add("Apple");
+    stringSet.add("Banana");
+    stringSet.add("Cherry");
 
     // Check whether the Set contains a given String
+    boolean containsBanana = stringSet.contains("Banana");
+    System.out.println("Set contains 'Banana': " + containsBanana);
 
     // Remove an element from the Set
+    stringSet.remove("Apple");
 
     // Get the size of the Set
+    int setSize = stringSet.size();
+    System.out.println("Size of the Set: " + setSize);
 
     // Iterate over the elements of the Set, printing each one on a separate line
+    for (String element : stringSet) {
+      System.out.println(element);
+    }
 
     /*
      * Warning!

src/StringPractice.java

@@ -1,25 +1,51 @@
+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 str = "HelloWorld";
 
     // Find the length of the string
+    int length = str.length();
+    System.out.println("Length of the string: " + length);
 
     // Concatenate (add) two strings together and reassign the result
+    str = str + " Java";
+    System.out.println("Concatenated string: " + str);
 
     // Find the value of the character at index 3
+    char charAtIndex3 = str.charAt(3);
+    System.out.println("Character at index 3: " + charAtIndex3);
 
-    // Check whether the string contains a given substring (i.e. does the string have "abc" in it?)
+    // Check whether the string contains a given substring (i.e., does the string have "abc" in it?)
+    boolean containsSubstring = str.contains("abc");
+    System.out.println("String contains 'abc': " + containsSubstring);
 
     // Iterate over the characters of the string, printing each one on a separate line
+    System.out.println("Characters in the string:");
+    for (char c : str.toCharArray()) {
+      System.out.println(c);
+    }
 
     // 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("Apple");
+    stringList.add("Banana");
+    stringList.add("Cherry");
 
     // 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(", ", stringList);
+    System.out.println("Joined string: " + joinedString);
 
     // Check whether two strings are equal
+    String str1 = "Hello";
+    String str2 = "Hello";
+    boolean areEqual = str1.equals(str2);
+    System.out.println("Strings are equal: " + areEqual);
 
     /*
      * Reminder!