#AP Computer Science A: Expressions and Assignment Statements - The Night Before 🚀

Hey! Let's make sure you're totally ready for tomorrow. This guide will help you nail those tricky questions on expressions and assignment statements. Let's dive in!

#1. Numeric Types and Basic Math in Java

# Basic Math Operations

Java handles addition, subtraction, and multiplication just like your calculator. Remember to use variables to store results.

java
int a = 1 + 2; // a is 3
double b = 1.0 + 3.5; // b is 4.5
int c = 3 - 5; // c is -2
double d = 24 * 1.0; // d is 24.0

• Assignment Operator (=): Evaluates the expression on the right and stores the result in the variable on the left.
• Integer vs. Double:
  • int operations with int result in an int.
  • Operations with at least one double result in a double.

# Incrementing and Decrementing

There are multiple ways to add or subtract 1 from a variable:

• Adding 1:
  • score = score + 1;
  • score += 1;
  • score++;
• Subtracting 1:
  • score = score - 1;
  • score -= 1;
  • score--;

# Modulo Operator (%)

The modulo operator % gives you the remainder of a division. Only works with integers where the divisor (b) is positive.

java
int a = 4 % 2; // a is 0 (4 = 2 * 2 + 0)
int b = 10 % 3; // b is 1 (10 = 3 * 3 + 1)
int c = 3 % 5; // c is 3 (3 = 0 * 5 + 3)

# Division

Division can be tricky! Pay close attention to data types.

java
int a = 5 / 2; // a is 2 (integer division)
double b = 5 / 2.0; // b is 2.5 (double division)

• Integer Division: Returns only the whole number quotient (truncates the decimal).
• Double Division: Returns the actual quotient as a decimal.

#2. Order of Operations

Java follows the standard order of operations (PEMDAS/BODMAS), with modulo included with multiplication and division.