AP CSA Unit 2 Practice Exam | 50 Free Questions

Question 1

Consider the following class. What happens when the code in main executes?

public class Dog {
    private String name;
    private int age;
}

// In main:
Dog d = new Dog();
System.out.println(d.name);

A) Prints null
B) Prints an empty string
C) Compile error
D) Runtime error

Question 2

What are the default values for these instance variables?

public class Example {
    private int number;
    private double value;
    private boolean flag;
    private String text;
}

A) 0, 0.0, false, null
B) 0, 0.0, true, ""
C) null, null, null, null
D) Compile error - must initialize

Question 3

Which access modifier makes an instance variable visible only within its own class?

A) public
B) private
C) protected
D) static

Question 4

What is printed?

public class Counter {
    private int count = 10;
    
    public int getCount() {
        return count;
    }
}

// In main:
Counter c1 = new Counter();
Counter c2 = new Counter();
System.out.println(c1.getCount() + c2.getCount());

A) 10
B) 20
C) 0
D) Compile error

Question 5

What is the primary purpose of encapsulation?

A) To make code run faster
B) To hide implementation details and protect data
C) To allow multiple inheritance
D) To reduce memory usage

Question 6

What is printed?

public class Box {
    private int width;
    private int height = 5;
    
    public int getArea() {
        return width * height;
    }
}

// In main:
Box b = new Box();
System.out.println(b.getArea());

A) 0
B) 5
C) Compile error
D) NullPointerException

Question 7

What is printed?

public class Point {
    private int x;
    private int y;
    
    public void setX(int x) {
        x = x;
    }
    
    public int getX() {
        return x;
    }
}

// In main:
Point p = new Point();
p.setX(10);
System.out.println(p.getX());

A) 10
B) 0
C) Compile error
D) null

Question 8

What is printed?

public class Point {
    private int x;
    private int y;
    
    public void setX(int newX) {
        this.x = newX;
    }
    
    public int getX() {
        return this.x;
    }
}

// In main:
Point p = new Point();
p.setX(10);
System.out.println(p.getX());

A) 10
B) 0
C) Compile error
D) null

Question 9

Which correctly declares an accessor (getter) method for a private variable called score?

A) public void getScore() { return score; }
B) public int getScore() { return score; }
C) private int getScore() { return score; }
D) public int score() { return score; }

Question 10

Which correctly declares a mutator (setter) method for a private int called age?

A) public void setAge(int a) { age = a; }
B) public int setAge(int a) { age = a; }
C) private void setAge(int a) { age = a; }
D) public void setAge() { age = a; }

Question 11

What is the scope of a local variable declared inside a method?

A) The entire class
B) Only the method where it is declared
C) All methods in the class
D) The entire program

Question 12

What happens if a local variable has the same name as an instance variable?

public class Test {
    private int value = 100;
    
    public void demo() {
        int value = 50;
        System.out.println(value);
    }
}

A) Prints 100
B) Prints 50
C) Compile error
D) Prints 150

Question 13

What is true about constructors?

A) They must have a return type
B) They must be named the same as the class
C) They can only be private
D) A class can only have one constructor

Question 14

What is printed?

public class Student {
    private String name;
    private int grade;
    
    public Student(String n, int g) {
        name = n;
        grade = g;
    }
    
    public int getGrade() {
        return grade;
    }
}

// In main:
Student s = new Student("Alice", 11);
System.out.println(s.getGrade());

A) 0
B) 11
C) null
D) Compile error

Question 15

What happens when this code executes?

public class Car {
    private String model;
    
    public Car(String m) {
        model = m;
    }
}

// In main:
Car c = new Car();

A) Creates Car with model = null
B) Creates Car with model = ""
C) Compile error
D) Runtime error

Question 16

What is printed?

public class Book {
    private String title;
    private int pages;
    
    public Book() {
        title = "Unknown";
        pages = 0;
    }
    
    public Book(String t, int p) {
        title = t;
        pages = p;
    }
    
    public String getTitle() {
        return title;
    }
}

// In main:
Book b = new Book();
System.out.println(b.getTitle());

A) null
B) Unknown
C) Compile error
D) Runtime error

Question 17

What is printed?

public class Circle {
    private double radius;
    
    public Circle() {
        this(1.0);
    }
    
    public Circle(double r) {
        radius = r;
    }
    
    public double getRadius() {
        return radius;
    }
}

// In main:
Circle c = new Circle();
System.out.println(c.getRadius());

A) 0.0
B) 1.0
C) Compile error
D) null

Question 18

Where must this() or super() appear in a constructor?

A) Anywhere in the constructor
B) As the first statement
C) As the last statement
D) Outside the constructor

Question 19

What is wrong with this constructor?

public class Person {
    private String name;
    
    public void Person(String n) {
        name = n;
    }
}

A) Nothing is wrong
B) It has void return type - not a constructor
C) Parameter name is wrong
D) name should be public

Question 20

What is printed?

public class Item {
    private static int count = 0;
    private int id;
    
    public Item() {
        count++;
        id = count;
    }
    
    public int getId() {
        return id;
    }
}

// In main:
Item a = new Item();
Item b = new Item();
Item c = new Item();
System.out.println(a.getId() + " " + b.getId() + " " + c.getId());

A) 1 1 1
B) 1 2 3
C) 3 3 3
D) 0 1 2

Question 21

What is printed?

public class Rectangle {
    private int width;
    private int height;
    
    public Rectangle(int w, int h) {
        width = w;
        height = h;
    }
    
    public Rectangle(int side) {
        this(side, side);
    }
    
    public int getArea() {
        return width * height;
    }
}

// In main:
Rectangle r = new Rectangle(5);
System.out.println(r.getArea());

A) 5
B) 10
C) 25
D) Compile error

Question 22

How many constructors can a class have?

A) Exactly one
B) At most two
C) Any number, as long as they have different parameter lists
D) Zero - constructors are optional

Question 23

What happens if you don't write any constructor for a class?

A) Compile error
B) Java provides a default no-argument constructor
C) You cannot create objects of that class
D) Runtime error when creating objects

Question 24

What is printed?

public class Account {
    private double balance;
    
    public Account() {
        balance = 100;
    }
    
    public Account(double initial) {
        balance = initial;
    }
    
    public double getBalance() {
        return balance;
    }
}

// In main:
Account a1 = new Account();
Account a2 = new Account(500);
System.out.println(a1.getBalance() + a2.getBalance());

A) 100.0
B) 500.0
C) 600.0
D) 0.0

Question 25

What is printed?

public class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
    
    public double add(double a, double b) {
        return a + b;
    }
}

// In main:
Calculator c = new Calculator();
System.out.println(c.add(3, 4));

A) 7
B) 7.0
C) Compile error - ambiguous
D) Runtime error

Question 26

What is printed?

public class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
    
    public double add(double a, double b) {
        return a + b;
    }
}

// In main:
Calculator c = new Calculator();
System.out.println(c.add(3.0, 4.0));

A) 7
B) 7.0
C) Compile error
D) Runtime error

Question 27

What is printed?

public class Counter {
    private int value = 0;
    
    public int increment() {
        value++;
        return value;
    }
    
    public int getValue() {
        return value;
    }
}

// In main:
Counter c = new Counter();
System.out.println(c.increment());
System.out.println(c.increment());
System.out.println(c.getValue());

A) 1, 2, 2
B) 1, 2, 3
C) 0, 1, 2
D) 1, 1, 1

Question 28

What is printed?

public class MathHelper {
    public int square(int n) {
        return n * n;
    }
    
    public int sumOfSquares(int a, int b) {
        return square(a) + square(b);
    }
}

// In main:
MathHelper m = new MathHelper();
System.out.println(m.sumOfSquares(3, 4));

A) 7
B) 12
C) 25
D) 49

Question 29

What is printed?

public class Processor {
    public void modify(int x) {
        x = x * 2;
    }
}

// In main:
Processor p = new Processor();
int num = 10;
p.modify(num);
System.out.println(num);

A) 10
B) 20
C) 0
D) Compile error

Question 30

What happens when a method has no return statement but declares a return type?

public int getValue() {
    int x = 5;
    // no return statement
}

A) Returns 0
B) Returns null
C) Compile error
D) Runtime error

Question 31

What is printed?

public class StringUtil {
    public String repeat(String s, int times) {
        String result = "";
        for (int i = 0; i < times; i++) {
            result += s;
        }
        return result;
    }
}

// In main:
StringUtil su = new StringUtil();
System.out.println(su.repeat("ab", 3));

A) ab
B) ababab
C) ab3
D) abab

Question 32

What is true about method overloading?

A) Methods must have different names
B) Methods must have the same parameter list
C) Methods must differ in parameter types, number, or order
D) Methods must have different return types

Question 33

What is printed?

public class Checker {
    public boolean isEven(int n) {
        return n % 2 == 0;
    }
    
    public boolean isBetween(int n, int low, int high) {
        return n >= low && n <= high;
    }
}

// In main:
Checker c = new Checker();
System.out.println(c.isEven(7) + " " + c.isBetween(5, 1, 10));

A) false true
B) true false
C) true true
D) false false

Question 34

What is printed?

public class Grader {
    public String getGrade(int score) {
        if (score >= 90) return "A";
        if (score >= 80) return "B";
        if (score >= 70) return "C";
        return "F";
    }
}

// In main:
Grader g = new Grader();
System.out.println(g.getGrade(85) + g.getGrade(65));

A) BF
B) B F
A) BC
D) CF

Question 35

What is printed?

public class Mystery {
    public int compute(int n) {
        if (n <= 1)
            return n;
        return compute(n - 1) + compute(n - 2);
    }
}

// In main:
Mystery m = new Mystery();
System.out.println(m.compute(5));

A) 5
B) 8
C) 3
D) 15

Question 36

What keyword is used to return early from a void method?

A) break
B) return
C) exit
D) stop

Question 37

What is printed?

public class Counter {
    private static int count = 0;
    
    public Counter() {
        count++;
    }
    
    public static int getCount() {
        return count;
    }
}

// In main:
Counter c1 = new Counter();
Counter c2 = new Counter();
Counter c3 = new Counter();
System.out.println(Counter.getCount());

A) 0
B) 1
C) 3
D) Compile error

Question 38

What is the main difference between static and instance variables?

A) Static variables can only be integers
B) Static variables are shared by all objects; instance variables are unique to each object
C) Instance variables are faster to access
D) Static variables must be private

Question 39

What happens when you try to access an instance variable from a static method?

public class Example {
    private int value = 10;
    
    public static void printValue() {
        System.out.println(value);
    }
}

A) Prints 10
B) Prints 0
C) Compile error
D) Runtime error

Question 40

How do you call a static method?

public class MathUtils {
    public static int square(int n) {
        return n * n;
    }
}

A) MathUtils m = new MathUtils(); m.square(5);
B) MathUtils.square(5);
C) square(5);
D) Both A and B work

Question 41

What is printed?

public class Test {
    private int x = 5;
    private static int y = 10;
    
    public void show() {
        System.out.print(x + " " + y);
    }
}

// In main:
Test t = new Test();
t.show();

A) 5 10
B) Compile error - can't access static from instance method
C) 0 10
D) 5 0

Question 42

What is printed?

public class Bank {
    private static double interestRate = 0.05;
    private double balance;
    
    public Bank(double b) {
        balance = b;
    }
    
    public static void setRate(double r) {
        interestRate = r;
    }
    
    public double getInterest() {
        return balance * interestRate;
    }
}

// In main:
Bank b1 = new Bank(1000);
Bank b2 = new Bank(2000);
Bank.setRate(0.10);
System.out.println(b1.getInterest() + " " + b2.getInterest());

A) 50.0 100.0
B) 100.0 200.0
C) 50.0 200.0
D) 100.0 100.0

Question 43

Can a static method call an instance method directly?

A) Yes, always
B) No, it needs an object reference first
C) Only if both are public
D) Only in the same class

Question 44

Which method in the Math class is an example of a static method?

A) Math.sqrt(16)
B) Math m = new Math(); m.sqrt(16)
C) new Math().sqrt(16)
D) sqrt(16)

Question 45

What is printed?

public class Point {
    public int x;
    public int y;
    
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
}

// In main:
Point p1 = new Point(3, 4);
Point p2 = p1;
p2.x = 10;
System.out.println(p1.x);

A) 3
B) 10
C) 0
D) Compile error

Question 46

What is printed?

public class Box {
    public int value;
    
    public Box(int v) {
        value = v;
    }
}

// In main:
Box b1 = new Box(5);
Box b2 = new Box(5);
System.out.println(b1 == b2);

A) true
B) false
C) Compile error
D) 5

Question 47

What is printed?

public class Modifier {
    public void change(Point p) {
        p.x = 100;
    }
}

public class Point {
    public int x = 5;
}

// In main:
Point pt = new Point();
Modifier m = new Modifier();
m.change(pt);
System.out.println(pt.x);

A) 5
B) 100
C) 0
D) null

Question 48

What is printed?

public class Reassigner {
    public void change(Point p) {
        p = new Point(100);
    }
}

public class Point {
    public int x;
    public Point(int x) { this.x = x; }
}

// In main:
Point pt = new Point(5);
Reassigner r = new Reassigner();
r.change(pt);
System.out.println(pt.x);

A) 5
B) 100
C) 0
D) null

Question 49

What is the value of a null reference?

String s = null;
System.out.println(s);

A) Prints nothing
B) Prints "null"
C) NullPointerException
D) Compile error

Question 50

What happens when this code runs?

String s = null;
System.out.println(s.length());

A) Prints 0
B) Prints null
C) NullPointerException
D) Compile error

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Unit 2 Practice Exam: Classes & Objects

Unit 2: Classes & Objects

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