#Multiple Choice Questions

1. What is the value of x after the following code executes? int x = 5; x += 3; x--;

   • 6
   • 7
   • 8
   • 9 Answer: 7

2. What is the value of y after the following code executes? int y = 10; y /= 2; y %= 3;

   • 0
   • 1
   • 2
   • 3 Answer: 2

#Free Response Question

1. Consider the following code segment:java\nint a = 12;\nint b = 5;\nint c = 0;\na -= b;\nb = 2;\nc = a % b;\na += c;\nb = a - b;\nc = b;\n``` \n\n(a) What are the final values of a, b, and c? Show your work by tracing the code.", "answer": "(a) \n a -= b; // a = 12 - 5 = 7\n b = 2; // b = 5 * 2 = 10\n c = a % b; // c = 7 % 10 = 7\n* a += c; // a = 7 + 7 = 14\n* b = a - b; // b = 14 - 10 = 4\n* c *= b; // c = 7 * 4 = 28\n\nFinal values: a = 14, b = 4, c = 28\n", "scoring": { "a": "1 point for correct value of a, 1 point for showing work", "b": "1 point for correct value of b, 1 point for showing work", "c": "1 point for correct value of c, 1 point for showing work" } } }

</div>

## 2. Control Flow <a id='control-flow'></a>

### 2.1. `if` Statements

*   Execute code blocks based on conditions.
*   `if (condition) { /* code */ }`
*   `if (condition) { /* code */ } else { /* code */ }`
*   `if (condition1) { /* code */ } else if (condition2) { /* code */ } else { /* code */ }`

### 2.2. `for` Loops

*   Repeat code a specific number of times.
*   `for (initialization; condition; update) { /* code */ }`
*   Example: `for (int i = 0; i < 10; i++) { /* code */ }`

### 2.3. `while` Loops

*   Repeat code while a condition is true.
*   `while (condition) { /* code */ }`
*   Be careful of infinite loops! ⚠️

### 2.4. Boolean Expressions

*   Combine conditions using `&&` (AND), `||` (OR), `!` (NOT).
*   `true && true` is `true`, `true && false` is `false`.
*   `true || false` is `true`, `false || false` is `false`.
*   `!true` is `false`, `!false` is `true`.

<div data-custom-tag="memory_aid"> 

Remember **AND** only returns true if **both** conditions are true. **OR** returns true if **at least one** condition is true. **NOT** reverses the boolean value.

</div>

<div data-custom-tag="common_mistake"> 

Be careful with the difference between `=` (assignment) and `==` (equality check) in conditions. Using `=` in an `if` statement will cause a compilation error.

</div>

### 2.5. Short-Circuit Evaluation

*   For `&&`, if the first condition is false, the second isn't evaluated.
*   For `||`, if the first condition is true, the second isn't evaluated.

 
<div data-custom-tag="practice_question"> 

## Multiple Choice Questions (MCQ)

### Question 1
What will be printed by the following code? `int x = 5; if (x > 3) { System.out.print("A"); } else { System.out.print("B"); }`
* A
* B
* AB
* Nothing
**Answer:** A

### Question 2
How many times will the following loop execute? `for (int i = 0; i < 7; i += 2) { System.out.print(i); }`
* 3
* 4
* 7
* 8
**Answer:** 4

## Free Response Question (FRQ)

### Question
Write a method `countEven` that takes an integer array `arr` and returns the number of even numbers in the array. For example, if `arr` is `{1, 2, 3, 4, 5, 6}`, the method should return `3`.
**Answer:**java\npublic int countEven(int[] arr) {\n    int count = 0;\n    for (int num : arr) {\n        if (num % 2 == 0) {\n            count++;\n        }\n    }\n    return count;\n}\n```
",
    "scoring": {
      "initialization": "1 point for initializing the count variable",
      "loop": "1 point for correct `for` or `while` loop structure",
      "conditional": "1 point for correct conditional statement to check for even numbers",
      "increment": "1 point for incrementing the count correctly",
      "return": "1 point for returning the correct count"
    }
  }
}

#Multiple Choice Questions

Question 1: What is the output of the following code? String s = "Computer"; System.out.println(s.substring(2, 5)); Options:

• mpu
• omp
• put
• mput Answer: mpu

Question 2: Which of the following correctly compares two strings str1 and str2 for equality? Options:

• str1 == str2
• str1.equals(str2)
• str1.compareTo(str2) == 0
• str1.equalsIgnoreCase(str2) Answer: str1.equals(str2)

#Free Response Question

Question: Write a method reverseString that takes a String str and returns its reversed version. For example, if str is "hello", the method should return "olleh". **Answer:**java\npublic String reverseString(String str) {\n String reversed = "";\n for (int i = str.length() - 1; i >= 0; i--) {\n reversed += str.charAt(i);\n }\n return reversed;\n}\n``` ", "scoring": { "initialization": "1 point for initializing the reversed string", "loop": "1 point for correct for loop structure (going backwards)", "character_access": "1 point for accessing the characters correctly", "concatenation": "1 point for concatenating the characters to the reversed string", "return": "1 point for returning the reversed string" } } }

</div>

## 4. Classes and Objects <a id='classes-objects'></a>

### 4.1. Classes

*   Blueprints for creating objects.
*   Contain data (fields/instance variables) and behavior (methods).
*   Example:
    ```
java
    public class Dog {
        private String name;
        private int age;

        public Dog(String name, int age) { ... }
        public void bark() { ... }
    }
    ```

### 4.2. Objects

*   Instances of a class.
*   Created using the `new` keyword: `Dog myDog = new Dog("Buddy", 3);`

### 4.3. Instance Variables

*   Data associated with each object.
*   Declared inside the class but outside any method.
*   Use `private` for encapsulation (data hiding).

### 4.4. Constructors

*   Special methods used to initialize objects.
*   Have the same name as the class.
*   No return type (not even `void`).

### 4.5. Methods

*   Define the behavior of objects.
*   Can have parameters and return values.
*   Example: `public void bark() { System.out.println("Woof!"); }`

### 4.6. `this` Keyword

*   Refers to the current object.
*   Used to distinguish between instance variables and parameters with the same name.

<div data-custom-tag="key_point"> 

Classes are like cookie cutters, and objects are the cookies. Each object has its own set of instance variables.

</div>

 
<div data-custom-tag="practice_question"> 

## Multiple Choice Questions

### Question 1
**Question:** Which keyword is used to create an object of a class?
**Options:**
*   class
*   object
*   new
*   instance
**Answer:** new

### Question 2
**Question:** What is the purpose of a constructor?
**Options:**
*   To create a class
*   To initialize an object
*   To define methods
*   To declare variables
**Answer:** To initialize an object

## Free Response Question

### Question
**Question:** Create a class `Rectangle` with the following:
    *   Instance variables: `width` (int) and `height` (int)
    *   Constructor: Takes `width` and `height` as parameters and initializes the instance variables.
    *   Method: `getArea()` that returns the area of the rectangle.
**Answer:**java\npublic class Rectangle {\n    private int width;\n    private int height;\n\n    public Rectangle(int width, int height) {\n        this.width = width;\n        this.height = height;\n    }\n\n    public int getArea() {\n        return width * height;\n    }\n}\n```
",
    "scoring": {
      "instance_variables": "1 point for declaring instance variables correctly",
      "constructor": "1 point for creating a constructor that initializes the instance variables",
      "getArea_method": "1 point for creating the `getArea` method",
      "return_value": "1 point for returning the correct area",
      "encapsulation": "1 point for using private instance variables"
    }
  }
}

#Multiple Choice Questions

Question 1: What is the index of the first element in an array?

• 0
• 1
• -1
• array.length Answer: 0

Question 2: What is the output of the following code? int[] arr = {1, 2, 3}; System.out.println(arr.length);

• 2
• 3
• 4
• Error Answer: 3

#Free Response Question

Question: Write a method sumArray that takes an integer array arr and returns the sum of all elements in the array. **Answer:**java\npublic int sumArray(int[] arr) {\n int sum = 0;\n for (int num : arr) {\n sum += num;\n }\n return sum;\n}\n``` ", "scoring": { "initialization": "1 point for initializing the sum variable", "loop": "1 point for correct for loop structure", "summation": "1 point for adding the elements correctly", "return": "1 point for returning the correct sum" } } }

</div>

## 6. ArrayList <a id='arraylist'></a>

### 6.1. ArrayList Basics

*   Dynamic, resizable arrays.
*   Part of the `java.util` package: `import java.util.ArrayList;`
*   Created using `new`: `ArrayList<Integer> numbers = new ArrayList<>();`

### 6.2. ArrayList Methods

*   `add(element)`: Adds an element to the end.
*   `add(index, element)`: Inserts an element at a specific index.
*   `get(index)`: Returns the element at a specific index.
*   `set(index, element)`: Replaces the element at a specific index.
*   `remove(index)`: Removes the element at a specific index.
*   `size()`: Returns the number of elements.

### 6.3. Traversing ArrayLists

*   Use `for` loops or enhanced `for` loops, similar to arrays.

`ArrayList` is a very important topic. Make sure you know how to add, remove, and access elements.

 
<div data-custom-tag="practice_question"> 

**MCQ Questions:**

**Question:** Which method is used to add an element to the end of an ArrayList?
**Options:**
- add()
- insert()
- append()
- push()
**Answer:** add()

**Question:** What is the output of the following code? `ArrayList<String> list = new ArrayList<>(); list.add("A"); list.add("B"); System.out.println(list.size());`
**Options:**
- 0
- 1
- 2
- Error
**Answer:** 2

**FRQ Question:**

**Question:** Write a method `removeEven` that takes an ArrayList of Integers and removes all even numbers from the list.
**Answer:**java\npublic void removeEven(ArrayList<Integer> list) {\n    for (int i = 0; i < list.size(); i++) {\n        if (list.get(i) % 2 == 0) {\n            list.remove(i);\n            i--; // Adjust index after removal\n        }\n    }\n}\n```
",
    "scoring": {
      "loop": "1 point for correct `for` loop structure",
      "conditional": "1 point for correct conditional statement to check for even numbers",
      "removal": "1 point for removing the element correctly",
      "index_adjustment": "1 point for adjusting the index after removal",
      "void_return": "1 point for not returning anything"
    }
  }
}

Multiple Choice Questions (MCQ):

1. Question: How do you access the element in the second row and third column of a 2D array named matrix? Options:

   • matrix[1][2]
   • matrix[2][1]
   • matrix[2, 3]
   • matrix[3, 2] Answer: matrix[1][2]

2. Question: What does matrix.length represent for a 2D array named matrix? Options:

   • Number of columns
   • Number of rows
   • Total number of elements
   • Length of the first row Answer: Number of rows

Free Response Question (FRQ):

Question: Write a method sum2DArray that takes a 2D array of integers and returns the sum of all elements in the array. **Answer:**java\npublic int sum2DArray(int[][] matrix) {\n int sum = 0;\n for (int row = 0; row < matrix.length; row++) {\n for (int col = 0; col < matrix[row].length; col++) {\n sum += matrix[row][col];\n }\n }\n return sum;\n}\n``` ", "scoring": { "initialization": "1 point for initializing the sum variable", "outer_loop": "1 point for correct outer for loop structure", "inner_loop": "1 point for correct inner for loop structure", "summation": "1 point for adding the elements correctly", "return": "1 point for returning the correct sum" } } }

</div>

## 8. Inheritance and Polymorphism <a id='inheritance-polymorphism'></a>

### 8.1. Inheritance

*   Allows a class (subclass/child) to inherit properties and methods from another class (superclass/parent).
*   Use the `extends` keyword: `public class Dog extends Animal { ... }`
*   Promotes code reuse and establishes an IS-A relationship.

### 8.2. `super` Keyword

*   Used to call the constructor or methods of the superclass.
*   Example: `super(name, age);`

### 8.3. Method Overriding

*   Subclass provides its own implementation of a method that is already defined in the superclass.
*   Use the `@Override` annotation.

### 8.4. Polymorphism

*   Ability of an object to take on many forms.
*   Achieved through inheritance and method overriding.
*   Example: `Animal myAnimal = new Dog(); myAnimal.makeSound();` (calls the `makeSound` method of the `Dog` class).

<div data-custom-tag="memory_aid"> 

Think of inheritance as a family tree. The child inherits traits from the parent. Polymorphism means "many forms," like a shape that can be a circle, square, or triangle.

</div>

 
<div data-custom-tag="practice_question"> 

**MCQ Questions:**

**Question:** Which keyword is used to indicate that a class inherits from another class?
**Options:**
- implements
- inherits
- extends
- includes
**Answer:** extends

**Question:** What is method overriding?
**Options:**
- Creating a new method
- Hiding a method
- Providing a new implementation of an inherited method
- Calling a superclass method
**Answer:** Providing a new implementation of an inherited method

**FRQ Question:**

**Question:** Create a class `Animal` with the following:
    *   Instance variable: `name` (String)
    *   Constructor: Takes `name` as a parameter and initializes the instance variable.
    *   Method: `makeSound()` that prints "Generic animal sound".
    Create a subclass `Dog` that extends `Animal` with the following:
    *   Constructor: Takes `name` as a parameter and calls the superclass constructor.
    *   Overrides the `makeSound()` method to print "Woof!".
**Answer:**java\nclass Animal {\n    private String name;\n    public Animal(String name) {\n        this.name = name;\n    }\n    public void makeSound() {\n        System.out.println(\"Generic animal sound\");\n    }\n}\n\nclass Dog extends Animal {\n    public Dog(String name) {\n        super(name);\n    }\n    @Override\n    public void makeSound() {\n        System.out.println(\"Woof!\");\n    }\n}\n```
",
    "scoring": {
      "animal_class": "1 point for creating the `Animal` class with correct instance variable and constructor",
      "animal_makeSound": "1 point for creating the `makeSound` method in `Animal` class",
      "dog_class": "1 point for creating the `Dog` class that extends `Animal`",
      "dog_constructor": "1 point for creating the `Dog` constructor that calls the superclass constructor",
      "dog_override": "1 point for correctly overriding the `makeSound` method in `Dog` class"
    }
  }
}

#Multiple Choice Questions

1. Question: What is a base case in a recursive method?

• The recursive call
• The condition that stops the recursion
• The method's return type
• The method's parameters Answer: The condition that stops the recursion

2. Question: What happens if a recursive method does not have a base case?

• It will run faster
• It will cause a StackOverflowError
• It will return 0
• It will return null Answer: It will cause a StackOverflowError

#Free Response Question

Question: Write a recursive method sumDigits that takes an integer n and returns the sum of its digits. For example, if n is 123, the method should return 6. **Answer:**java\npublic int sumDigits(int n) {\n if (n < 10) {\n return n; // Base case\n } else {\n return n % 10 + sumDigits(n / 10); // Recursive step\n }\n}\n``` ", "scoring": { "base_case": "1 point for correct base case", "recursive_call": "1 point for correct recursive call", "modulus": "1 point for using modulus operator correctly", "division": "1 point for using division operator correctly", "return": "1 point for returning the correct sum" } } }

</div>

## Final Exam Focus 🎯

### High-Priority Topics

*   **Primitive Types and Operators**: Essential for all code.
*   **Control Flow**: `if`, `for`, `while` are fundamental.
*   **String Class**: Common in many problems.
*   **Classes and Objects**: Core to object-oriented programming.
*   **Arrays and ArrayLists**: Data structures you'll use frequently.
*   **Inheritance and Polymorphism**: Key for advanced topics.
*   **Recursion**: Appears in some FRQs.

### Common Question Types

*   **Multiple Choice**: Testing knowledge of concepts and code tracing.
*   **Free Response**: Writing methods, classes, and algorithms.

### Last-Minute Tips

*   **Time Management**: Don't spend too long on one question. Move on and come back if needed.
*   **Code Tracing**: Practice tracing code carefully, especially with loops and conditional statements.
*   **Read Carefully**: Pay attention to the details in the question. Understand what the problem is asking before you start coding.
*   **Practice, Practice, Practice**: The more you practice, the more confident you'll feel.

### You've Got This! 🎉

Remember, you've come a long way. Take a deep breath, stay calm, and trust your preparation. You're ready to rock this exam! Go get 'em! 🚀