Expressions and Assignment Statements in Java

Welcome to the world of programming! Today, we'll dive into some fundamental concepts in Java: expressions and assignment statements. These are the building blocks of any program. Let's break them down step by step.

1. Literals

A literal is a fixed value that we write directly in the code. Think of it as a number or text that doesn't change. Here are some examples:

• 5 is an integer literal.
• 3.14 is a double literal.
• "Hello, World!" is a string literal.

2. Arithmetic Expressions

Arithmetic expressions use arithmetic operators to perform calculations. The basic operators are:

• + for addition
• - for subtraction
• * for multiplication
• / for division
• % for modulus (remainder)

Examples:

• 5 + 3 results in 8
• 10 - 2 results in 8
• 4 * 2 results in 8
• 16 / 2 results in 8
• 17 % 3 results in 2 (because 17 divided by 3 leaves a remainder of 2)

3. Integer and Double Arithmetic

• When we perform arithmetic with two int values, the result is an int.
• When we perform arithmetic with a double value, the result is a double.

Examples:

• 5 + 3 is int + int, so the result is int (8).
• 5.0 + 3 is double + int, so the result is double (8.0).

4. Compound Expressions

We can combine multiple arithmetic operations in one expression. For example, 5 + 3 * 2 is a compound expression.

Operator Precedence

Operator precedence determines the order in which operations are performed. Multiplication and division have higher precedence than addition and subtraction.

Example:

• 5 + 3 * 2 is evaluated as 5 + (3 * 2), resulting in 11.

5. Division by Zero

Attempting to divide an integer by zero in Java will result in an ArithmeticException.

Example:

• 10 / 0 will cause an error.

6. Assignment Statements

An assignment statement assigns a value to a variable. It uses the = operator.

Example:

int a = 5; // Assigns the value 5 to the variable a

Real-World Example

Imagine you are calculating the total cost of items in a shopping cart. Each item has a price, and you want to find the total.

Example:

double item1 = 5.99;

double item2 = 3.49;

double totalCost = item1 + item2;

System.out.println("Total cost: " + totalCost);

Full Program Demonstrating the Concepts

Here is a simple Java program that demonstrates arithmetic expressions and assignment statements:

public class ArithmeticDemo {

    public static void main(String[] args) {

        // Literals

        int num1 = 10; // integer literal

        double num2 = 5.5; // double literal

        // Arithmetic expressions

        int sum = num1 + 5; // addition

        double product = num2 * 2; // multiplication

        // Compound expression

        double result = (num1 + 5) * num2; // (10 + 5) * 5.5 = 15 * 5.5 = 82.5

        // Division by zero (uncommenting the next line will cause an error)

        // int error = num1 / 0;

        // Printing the results

        System.out.println("Sum: " + sum);

        System.out.println("Product: " + product);

        System.out.println("Result: " + result);

    }

}

Programming Problem

Write a program that calculates the average of three numbers. Use literals for the three numbers and use arithmetic expressions to find their average. Then, print the result.

Steps:

1. Assign three numbers to three different variables.
2. Calculate the sum of the three numbers.
3. Divide the sum by 3 to find the average.
4. Print the average.

Example:

public class AverageCalculator {

    public static void main(String[] args) {

        // Step 1: Assign numbers to variables

        int num1 = 8;

        int num2 = 12;

        int num3 = 15;

        // Step 2: Calculate the sum

        int sum = num1 + num2 + num3;

        // Step 3: Calculate the average

        double average = sum / 3.0;

        // Step 4: Print the average

        System.out.println("Average: " + average);

    }

}

Happy coding! Understanding these basics will set a strong foundation for your programming journey.