AP CSA Unit 1 Exam (2025) - Objects, Methods & Expressions

Time: 45:00

AP Computer Science A Unit 1 Exam (2025)

Objects, Methods & Expressions

This exam is designed for the 2025-2026 AP CSA 4-Unit curriculum and focuses on foundational programming concepts.

Unit 1 introduces how Java programs are written, executed, and reasoned about. These concepts appear in nearly every AP CSA exam question.

This assessment includes high-difficulty multiple-choice questions modeled after:

The official AP Computer Science A Course and Exam Description (CED)
Barron's AP CSA challenge problems
CodeHS and AP Classroom progress-check style questions
Common AP CSA pitfalls from high-scoring students and teachers

Unit 1 Topics Covered:

Creating objects and calling methods
Primitive types vs object references
Integer vs floating-point arithmetic
String methods and immutability
Method parameters and return values
Using the Java Math API
Operator precedence and evaluation

Exam Tip: Many Unit 1 errors come from integer division, String immutability, and misunderstanding method return values. Pay close attention to details.

30 Multiple Choice Questions | 45 minutes | Submit at bottom when complete

Question 1

What is printed?

int a = 7;
int b = 2;
double x = a / b;
System.out.println(x);

A) 3.5 B) 3 C) 3.0 D) 3.5 as a double

Answer: C
Integer division occurs first (7 / 2 = 3), then the result is stored as 3.0 in the double variable.

Question 2

Which expression evaluates to true?

A) 5 / 2 == 2.5 B) 5 % 2 == 0 C) (double)5 / 2 == 2.5 D) 5 / 2.0 == 2

Answer: C
Casting 5 to double forces floating-point division: 5.0 / 2 = 2.5.

Question 3

Which method call correctly reads an integer from the keyboard using a Scanner object named input?

A) Scanner.nextInt() B) input.nextInt() C) nextInt(input) D) Scanner.readInt()

Answer: B
Instance methods are called on the object variable, not the class name.

Question 4

What is the value of x after execution?

int x = 5;
x += 4;
x *= 2;
x -= 3;

A) 10 B) 13 C) 15 D) 21

Answer: C
Step by step: 5 + 4 = 9, then 9 * 2 = 18, then 18 - 3 = 15.

Question 5

What does the following produce?

System.out.println(Math.abs(-7) + Math.pow(2, 3));

A) 15.0 B) 11.0 C) 8.0 D) 9.0

Answer: A
Math.abs(-7) = 7, Math.pow(2,3) = 8.0, so 7 + 8.0 = 15.0.

Question 6

Which is a valid constructor call?

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

Answer: C
Correct constructor syntax: Type variableName = new Type(arguments);

Question 7

What is printed?

String s = "APCSA";
System.out.println(s.substring(2));

A) CSA B) PCSA C) APC D) SA

Answer: A
substring(2) returns characters from index 2 to the end: "CSA".

Question 8

Which statement about Strings is TRUE?

A) Strings are mutable objects B) The == operator compares String contents C) String methods modify the original String D) Strings are immutable objects

Answer: D
Strings are immutable. All String methods return new String objects rather than modifying the original.

Question 9

What is printed?

String s = "code";
s.toUpperCase();
System.out.println(s);

A) CODE B) Code C) code D) Runtime error

Answer: C
The returned uppercase String is ignored. The original String s is unchanged because Strings are immutable.

Question 10

Which generates a random integer from 0 to 9 (inclusive)?

A) (int)(Math.random() * 10) B) (int)(Math.random()) * 10 C) Math.random(10) D) (int)Math.random(10)

Answer: A
Math.random() returns [0.0, 1.0). Multiply by 10 gives [0.0, 10.0). Casting to int gives 0-9.

Question 11

What is printed?

int x = 4;
double y = x / 3;
System.out.println(y);

A) 1.33 B) 1 C) 1.0 D) 1.333333

Answer: C
Integer division (4 / 3 = 1) happens first, then the result is stored as 1.0 in the double.

Question 12

Consider the following code segment. What value is returned by Math.round(4.6)?

A) 4 B) 5 C) 4.0 D) 5.0

Answer: B
Math.round() rounds to the nearest integer. 4.6 rounds to 5 (returns a long).

Question 13

What is printed?

String s = "hello";
System.out.println(s.length() - 1);

A) 4 B) 5 C) 6 D) Compile error

Answer: A
"hello" has length 5, so 5 - 1 = 4. This is also the last valid index.

Question 14

Which expression correctly extracts the last character of a String s?

A) s.charAt(s.length()) B) s.charAt(s.length() - 1) C) s.substring(s.length()) D) s.charAt(-1)

Answer: B
Indices go from 0 to length-1. The last character is at index length() - 1.

Question 15

What is printed?

int x = 5;
System.out.println(x++ + ++x);

A) 10 B) 11 C) 12 D) 13

Answer: C
x++ returns 5 (then x becomes 6), ++x increments first (x becomes 7) then returns 7. So 5 + 7 = 12.

Question 16

Which statement about method parameters in Java is TRUE?

A) Primitive parameters are passed by reference B) Objects are copied entirely when passed C) Object references are passed by value D) Methods can modify primitive arguments in the caller

Answer: C
Java passes everything by value. For objects, the reference is copied, not the object itself.

Question 17

What is printed?

String a = "cat";
String b = a;
a = "dog";
System.out.println(b);

A) cat B) dog C) null D) Compile error

Answer: A
b still references the original String "cat". Reassigning a to "dog" does not affect b.

Question 18

Which correctly compares two Strings s1 and s2 for equal content?

A) s1 == s2 B) s1.equals(s2) C) s1.compareTo(s2) D) String.match(s1, s2)

Answer: B
The equals() method compares String contents. The == operator compares references.

Question 19

What is printed?

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

A) 3 B) 5 C) 7 D) 8

Answer: B
Math.min(5, 7) = 5, then Math.max(3, 5) = 5.

Question 20

Which expression truncates a double x to an int (removing the decimal without rounding)?

A) Math.round(x) B) Math.floor(x) C) (int)x D) Math.ceil(x)

Answer: C
Casting to int truncates the decimal portion without rounding.

Question 21

What is printed?

String s = "abc";
System.out.println(s.substring(0, 2));

A) ab B) abc C) bc D) a

Answer: A
substring(0, 2) returns characters from index 0 up to (but not including) index 2: "ab".

Question 22

Which Math class method returns the absolute value of a number?

A) Math.abs() B) Math.absolute() C) Math.value() D) Math.positive()

Answer: A
Math.abs() returns the absolute value.

Question 23

What range of values can x have after this statement executes?

int x = (int)(Math.random() * 5);

A) Always 5 B) 0 to 4 C) 1 to 5 D) 0 to 5

Answer: B
Math.random() returns [0.0, 1.0). Multiplying by 5 gives [0.0, 5.0). Casting to int gives 0, 1, 2, 3, or 4.

Question 24

Which correctly declares a method that returns a double?

A) public double calculate() B) public calculate double() C) double public calculate() D) public void calculate()

Answer: A
Correct syntax: access modifier, return type, method name, parameters.

Question 25

What is printed?

int x = 10;
x = x / 4;
System.out.println(x);

A) 2 B) 2.5 C) 3 D) Compile error

Answer: A
Integer division: 10 / 4 = 2 (decimal is truncated).

Question 26

Which is a valid Math API call to calculate 2 raised to the power of 3?

A) Math.power(2, 3) B) Math.pow(2, 3) C) Math.square(3) D) Math.exp(2, 3)

Answer: B
Math.pow(base, exponent) calculates base^exponent.

Question 27

Which operator concatenates Strings in Java?

A) * B) & C) + D) ++

Answer: C
The + operator concatenates Strings when at least one operand is a String.

Question 28

What is printed?

System.out.println("AP" + 5 + 2);

A) AP7 B) AP52 C) AP 5 2 D) Compile error

Answer: B
Left to right: "AP" + 5 = "AP5", then "AP5" + 2 = "AP52". String concatenation, not addition.

Question 29

Which expression evaluates to false?

A) 3 < 5 B) 4 == 4 C) 7 <= 6 D) 2 != 3

Answer: C
7 is not less than or equal to 6, so this is false.

Question 30

Which scenario BEST demonstrates when to use a method with a return value?

A) Printing a message to the console B) Updating an instance variable only C) Calculating a result and sending it back to the caller D) Reading user input from keyboard

Answer: C
Return values are used when the method needs to send data back to the caller.

Unit 1 Exam Results

0/30

AP Tip: Review missed questions carefully. Unit 1 errors often come from integer division, String immutability, and misunderstanding method return values.

Section II: Free Response Questions

These questions assess your ability to write Java code involving objects, methods, return values, and expressions.

FRQ 1 - Method Return Values

Write a method average that takes two int parameters and returns their average as a double.

Your method must avoid integer division truncation.

public static double average(int a, int b)

Example Calls:

average(4, 6)    returns 5.0
average(1, 2)    returns 1.5
average(7, 8)    returns 7.5

AP Tip: If both operands are integers, Java performs integer division. Cast at least one to double to get decimal result.

FRQ 2 - String Methods

Write a method endsMatch that returns true if the first and last characters of a String are the same, and false otherwise.

Assume the string has a length of at least 1.

public static boolean endsMatch(String str)

Example Calls:

endsMatch("radar")   returns true
endsMatch("apple")   returns false
endsMatch("a")       returns true

AP Tip: Use charAt() to get individual characters, or substring() to extract portions of a String.

Java Sandbox

Use the sandbox below to write and test your FRQ solutions:

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