Unit 1 Practice Exam: Objects and Methods | AP CSA

AP CSA Practice Exam

Unit 1 Practice Exam: Objects and Methods

50 Questions • 2025-2026 Curriculum • Unit 1: Objects, Strings, Math, Wrappers (15-25% of exam)

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Exam Overview: Unit 1 covers 15-25% of the AP CSA exam. The full AP CSA exam is 42 MCQ (55%) plus 4 FRQ (45%), delivered fully digitally via Bluebook. Topics in this set: object creation and references, String methods, type conversion, wrapper classes, and the Math class. Formats: Error Detection, I/II/III multi-select, and Predict the Output — all at AP exam difficulty.

Section 1: Object Creation and References

Error Detection

Question 1

Consider the following code segment. What will happen when this code is executed?

String data = null;
int len = data.length();
System.out.println(len);

A. The code prints 0 B. A NullPointerException is thrown at runtime C. A compile-time error occurs because the variable is uninitialized D. The code prints null

I/II/III Format

Question 2

Consider the following code segment:

String a = "Code";
String b = "Code";
String c = new String("Code");
String d = a;

Which of the following statements evaluate to true?

I. a == b
II. a == c
III. a == d

A. I only B. III only C. I and III only D. I, II, and III

Error Detection

Question 3

A student wrote the following code intending to concatenate " Data" onto the variable and print the result. What will actually be printed?

String a = "Test";
String b = a.toUpperCase();
a.concat(" Data");
System.out.println(a);

A. Test Data B. TEST Data C. Test D. TEST

Predict the Output

Question 4

Before looking at the choices, trace the code and predict the output.

String m = "Java";
String n = m;
m = "Python";
System.out.println(m + " " + n);

A. Python Java B. Java Java C. Python Python D. Java Python

Error Detection

Question 5

Which of the following is NOT a valid way to declare and initialize a Scanner object to read from the console?

A. Scanner input = new Scanner(System.in); B. Scanner input = Scanner(System.in); C. Scanner input; input = new Scanner(System.in); D. Scanner sc = new Scanner(System.in);

I/II/III Format

Question 6

Consider the following declarations:

Integer num1 = 100;
Integer num2 = 100;
Integer num3 = 1000;
Integer num4 = 1000;

Which of the following evaluate to true?

I. num1 == num2
II. num3 == num4
III. num1.equals(num2)

A. I only B. II and III only C. I, II, and III D. I and III only

Predict the Output

Question 7

Before looking at the choices, predict what the following code segment prints.

String val = "";
System.out.println(val == null);
System.out.println(val.length());

A. true then NullPointerException B. false then 0 C. false then 1 D. true then 0

Error Detection

Question 8

A student is debugging code and finds the following segment. What does it print?

String s1 = "AP";
String s2 = "ap";
boolean check = s1.equalsIgnoreCase(s2) && (s1 == s2);
System.out.println(check);

A. true because equalsIgnoreCase makes both sides true B. A compile-time error occurs C. false; s1 == s2 is false because they are different String objects D. true because the JVM interns all String literals

Predict the Output

Question 9

Before looking at the choices, trace the code and predict the output.

String p = new String("Test");
String q = new String("Test");
String r = p;
System.out.println(p.equals(q) + " " + (p == r));

A. true true B. true false C. false true D. false false

I/II/III Format

Question 10

Consider the following code segment:

Object ref;
// Line inserted here
System.out.println(ref);

Which of the following lines, when inserted, allow the code to compile AND run without an exception?

I. ref = "Hello";
II. ref = Integer.valueOf(42);
III. ref = null;

A. I only B. I and II only C. I and III only D. I, II, and III

Predict the Output

Question 11

Before looking at the choices, determine the output of the following code.

int count = 0;
String s = "banana";
for (int i = 0; i < s.length(); i++) {
    if (s.substring(i, i+1).equals("a")) count++;
}
System.out.println(count);

A. 2 B. 3 C. 4 D. 6

Error Detection

Question 12

A student intends to swap the values of two Integer objects. What actually happens when this code runs?

public static void swap(Integer a, Integer b) {
    Integer temp = a;
    a = b;
    b = temp;
}

// In main:
Integer x = 10, y = 20;
swap(x, y);
System.out.println(x + " " + y);

A. 20 10 -- the swap succeeds B. 10 20 -- Java passes references by value; local reassignments in swap do not affect x and y C. A compile-time error because Integer objects cannot be swapped D. 10 10 -- autoboxing causes both to reference the same cached object

Section 2: String Methods

Predict the Output

Question 13

Before looking at the choices, trace the method calls and predict the output.

String text = "examination";
System.out.println(text.substring(2, 6));

A. amin B. amina C. xami D. xamin

Error Detection

Question 14

What happens when the following code executes?

String word = "Java";
String ch = word.substring(4, 5);

A. ch is assigned the letter a B. ch is assigned a single space C. A StringIndexOutOfBoundsException is thrown at runtime D. A compile-time error occurs

I/II/III Format

Question 15

Consider String str = "Hello World". Which of the following expressions evaluate to true?

I. str.indexOf("o") == str.lastIndexOf("o")
II. str.substring(6).equals("World")
III. str.length() == 11

A. I only B. I and III only C. I, II, and III D. II and III only

Error Detection

Question 16

A student wants to print the FIRST and LAST occurrences of "ss" in a string. Identify the bug.

String phrase = "Mississippi";
int pos1 = phrase.lastIndexOf("ss");
int pos2 = phrase.indexOf("ss");
System.out.println("First: " + pos1 + ", Last: " + pos2);

A. The variables are swapped: pos1 stores the LAST occurrence (5) and pos2 stores the FIRST (2), so the labels print backwards B. The code is correct and prints First: 2, Last: 5 C. A StringIndexOutOfBoundsException is thrown D. The code prints First: 5, Last: 2 and is correct because indexOf searches right-to-left

Predict the Output

Question 17

Before looking at the choices, trace the method chain and predict the output.

String data = "Computer Science";
String result = data.substring(0, 8).toLowerCase();
System.out.println(result);

A. computer B. Computer C. compute D. COMPUTER

Predict the Output

Question 18

Before looking at the choices, predict the output of the following code.

String input = "  spaces  ";
System.out.println("[" + input + "]");
System.out.println("[" + input.substring(2, 8) + "]");

A. [ spaces ] then [spaces] B. [ spaces ] then [spaces] C. [spaces] twice D. [ spaces ] then [ space]

I/II/III Format

Question 19

Consider the following code segment:

String original = "apple";
String modified = original.toUpperCase();

Which of the following statements are true after this code executes?

I. original.equals("apple")
II. modified.equals("APPLE")
III. original == modified

A. I only B. II only C. I and II only D. I, II, and III

Error Detection

Question 20

A student expects the following code to print PrograXXing. What will actually be printed?

String s = "Programming";
String t = s.replace("m", "X");
System.out.println(s);

A. PrograXXing B. PrograXming C. ProgramXing D. Programming

Predict the Output

Question 21

Before looking at the choices, predict the output of the following code.

String s = "12345";
System.out.println(s.substring(1, 4).length());

A. 2 B. 3 C. 4 D. 5

I/II/III Format

Question 22

Consider String data = "ABCABC". Which of the following statements are true?

I. data.indexOf("X") == -1
II. data.indexOf("ABC") == 0
III. data.lastIndexOf("ABC") == 3

A. I only B. I and II only C. II and III only D. I, II, and III

Error Detection

Question 23

A student uses == to compare Strings. What does this code print?

String text = "Testing";
if (text.compareTo("Test") == 0) {
    System.out.println("Equal");
} else if (text == "Test") {
    System.out.println("Same reference");
} else {
    System.out.println("Not equal");
}

A. Not equal B. Equal because Testing starts with Test C. Same reference D. A compile-time error because == cannot compare Strings

Predict the Output

Question 24

Before looking at the choices, predict the output of the following code.

String s = "abcdefg";
System.out.println(s.substring(s.indexOf("d")));

A. defg B. efg C. abc D. d

Section 3: String Concatenation and Type Conversion

Predict the Output

Question 25

Before looking at the choices, predict the output. Pay close attention to operator precedence.

int a = 4;
int b = 2;
System.out.println("Result: " + a + b * 2);

A. Result: 12 B. Result: 424 C. Result: 8 D. Result: 44

Predict the Output

Question 26

Before looking at the choices, predict the output of the following code.

System.out.println(3 + 4 + "5" + 6 + 7);

A. 34567 B. 25 C. 3 + 4 + 5 + 6 + 7 D. 7567

Error Detection

Question 27

Which of the following will cause a compile-time error?

A. int x = (int) 3.7; B. double y = 5; C. int z = 3.5; D. double w = (double) 10;

Predict the Output

Question 28

Before looking at the choices, predict the output of the following code.

int value = 17;
int divisor = 5;
System.out.println(value / divisor + " R " + value % divisor);

A. 3 R 2 B. 3.4 R 2 C. 4 R 2 D. 3 R 0

Error Detection

Question 29

A student runs the following code expecting it to print 12. What will actually happen?

String input = "12.5";
int value = Integer.parseInt(input);
System.out.println(value);

A. Prints 12 after truncating the decimal B. Prints 13 after rounding C. A NumberFormatException is thrown at runtime D. A compile-time error occurs

Predict the Output

Question 30

Before looking at the choices, determine the value of result.

String input = "42";
int num = Integer.parseInt(input);
double result = num / 4.0;

A. 10 B. 10.0 C. 10.5 D. 424.0

I/II/III Format

Question 31

Consider the following expressions where x = 10 and y = 3. Which expressions evaluate to 3?

I. x / y
II. x % y
III. (int)(x / (double) y)

A. I only B. I and III only C. I, II, and III D. II only

Predict the Output

Question 32

Before looking at the choices, predict the output of the following code.

String s = "25";
String t = "5";
System.out.println(s + t + " vs " + (Integer.parseInt(s) + Integer.parseInt(t)));

A. 255 vs 30 B. 30 vs 30 C. 255 vs 255 D. 25 + 5 vs 30

Section 4: Wrapper Classes and Autoboxing

Predict the Output

Question 33

Before looking at the choices, trace the code and predict the output.

Integer val = 50;
int primitive = val;
val = val + 10;
System.out.println(primitive + " " + val);

A. 60 60 B. 50 50 C. A compile-time error occurs D. 50 60

Error Detection

Question 34

A student writes the following code expecting it to print 0. What actually happens?

Integer y = null;
int z = y;
System.out.println(z);

A. Prints 0 because null unboxes to the default int value B. Prints null C. A compile-time error occurs D. A NullPointerException is thrown at runtime during unboxing

I/II/III Format

Question 35

Which of the following code segments compile WITHOUT a compile-time error?

I. Integer x = 5; x++;
II. Integer y = null; int z = y;
III. int a = 10; Integer b = a;

A. I only B. I and III only C. I, II, and III D. III only

Error Detection

Question 36

A student writes the following code expecting true. What will actually be printed?

Integer a = 150;
Integer b = 150;
System.out.println(a == b);

A. true -- Integer objects are always cached B. true -- == on Integer compares values C. A compile-time error occurs D. false -- 150 is outside the Integer cache range (-128 to 127), so a and b are different objects

Predict the Output

Question 37

Before looking at the choices, predict the output of the following code.

System.out.println(Integer.MAX_VALUE + 1);

A. 2147483648 B. -2147483648 C. An overflow exception is thrown D. 0

Predict the Output

Question 38

Before looking at the choices, predict the output of the following code.

Double d = 3.14159;
System.out.println(d.intValue() + " " + Math.round(d));

A. 3 3 B. 3 4 C. 3.0 3 D. 4 3

Section 5: Math Class

Error Detection

Question 39

A student wants to generate a random integer between 5 and 15 INCLUSIVE. Which code correctly accomplishes this?

A. (int)(Math.random() * 10) + 5 B. (int)(Math.random() * 15) + 5 C. (int)(Math.random() * 10 + 5) D. (int)(Math.random() * 11) + 5

I/II/III Format

Question 40

Which of the following expressions ALWAYS return a value of type double?

I. Math.pow(2, 3)
II. Math.sqrt(16)
III. Math.abs(-5)

A. I only B. I and II only C. II and III only D. I, II, and III

Predict the Output

Question 41

Before looking at the choices, predict what values n can hold after the following code executes.

int n = (int)(Math.random() * 6);

A. 1, 2, 3, 4, 5, 6 B. 0, 1, 2, 3, 4, 5, 6 C. 1, 2, 3, 4, 5 D. 0, 1, 2, 3, 4, 5

Error Detection

Question 42

A student wants code that produces values from the set {0, 5, 10, 15}. Does the following code work as intended?

int mystery = (int)(Math.random() * 4) * 5;

A. Yes -- the cast gives 0, 1, 2, or 3; multiplying by 5 gives {0, 5, 10, 15} B. No -- the multiplication happens before casting, giving a continuous range 0-20 C. No -- the range is shifted by one, giving {5, 10, 15, 20} D. No -- the wrong multiplier is used, giving {0, 4, 8, 12}

Predict the Output

Question 43

Before looking at the choices, predict the output of the following code.

System.out.println(Math.min(Math.max(3, 7), 5));

A. 3 B. 5 C. 7 D. 15

Error Detection

Question 44

Which statement about Math.random() is NOT correct?

A. It returns a value greater than or equal to 0.0 B. It returns a value strictly less than 1.0 C. It can return exactly 1.0 D. It returns a double value

I/II/III Format

Question 45

Which of the following expressions are ALWAYS true regardless of the value of x?

I. Math.abs(x) >= 0
II. Math.abs(x) == x
III. Math.abs(-x) == Math.abs(x)

A. I only B. I and III only C. II and III only D. I, II, and III

Predict the Output

Question 46

Before looking at the choices, trace the code and predict the output.

double d = -3.7;
System.out.println(Math.abs((int) d) + " " + (int) Math.abs(d));

A. 3 3 B. 4 4 C. 3 4 D. 4 3

Predict the Output

Question 47

Before looking at the choices, predict the output of the following code.

System.out.println(Math.sqrt(Math.pow(3, 2) + Math.pow(4, 2)));

A. 5.0 B. 7.0 C. 25.0 D. 12.0

I/II/III Format

Question 48

Consider int a = -8; int b = 3;. Which of the following expressions evaluate to 2?

I. Math.abs(a % b)
II. a % Math.abs(b)
III. Math.abs(a) % b

A. I only B. I and III only C. II and III only D. I, II, and III

Error Detection

Question 49

A student wants to generate a random number from 1 to 10 INCLUSIVE. Which implementation is INCORRECT?

A. (int)(Math.random() * 10) + 1 B. (int)(Math.random() * 11) C. 1 + (int)(Math.random() * 10) D. (int)(Math.random() * 9) + 1

Predict the Output

Question 50

Before looking at the choices, predict the output of the following code.

System.out.println((int) Math.pow(2, 10));

A. 1024 B. 20 C. 1024.0 D. 100

All Unit Exams Unit 2: Selection & Iteration →

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