Question

State the order of evaluation of the operators in each of the following Java statements, and show the value of x after each statement is performed: a) x = 7 + 3 * 6 / 2 - 1; b) x = 2 % 2 + 2 * 2 - 2 / 2; c) x = (3 * 9 * (3 + (9 * 3 / (3))));

Short answer

The final values of x are: a) 15, b) 3, c) 324.

Step-by-step solution

Evaluate statement a)

Follow the order of operations: Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right). First perform the multiplication 3 * 6 to get 18, then divide by 2 to get 9, add 7 to get 16, and finally subtract 1 to get 15. So the value of x is 15.

Evaluate statement b)

Again, follow the order of operations. First perform the remainder operation 2 % 2 which is 0, then multiplication 2 * 2 to get 4, and division 2 / 2 to get 1. Add and subtract in sequence to get 0 + 4 - 1, which evaluates to 3. So the value of x is 3.

Evaluate statement c)

Parentheses inside parentheses should be evaluated first. Start with the innermost (9 * 3), which is 27. Divide 27 by 3 to get 9. Then add 3 to get 12. Multiply the outer parentheses 3 * 9 to get 27, and then multiply by 12 to get the final value of x as 324.

Key concepts

Order of Operations

When it comes to arithmetic, the 'order of operations' is a foundational concept that dictates the sequence in which the operations within an expression should be performed to accurately calculate its value. In Java, the order follows a specific hierarchy similar to traditional mathematics. To remember this order, one can use the acronym PEMDAS, which stands for Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right).

For example, in the expression \(7 + 3 * 6 / 2 - 1\), the multiplication \(3 * 6\) happens before the division \(6 / 2\), which in turn is before addition \(7 + 9\) and finally subtraction \(16 - 1\). Understanding and applying this rule ensures accurate results in all calculations.

Arithmetic Operators in Java

Java provides a set of arithmetic operators that allow you to perform calculations on numeric data. These include the basic addition \(+\), subtraction \(–\), multiplication \(\times\), and division \(\div\) operators. Additionally, Java includes the modulus operator \(\%\), which returns the remainder after division. For instance, in the equation \(x = 2 \% 2 + 2 * 2 - 2 / 2\), the modulus operator is used to find the remainder of \(2 \div 2\), which is 0.

Each operator has a precedence level where multiplication, division, and modulus are evaluated before addition and subtraction. This precedence can be altered using parentheses, as in \(x = (3 * 9 * (3 + (9 * 3 / (3))))\), where operations inside the parentheses are computed first, following the rules of operator precedence.

Evaluating Expressions

Evaluating expressions in Java involves performing calculations according to the sequence determined by operator precedence or any overridden order using parentheses. For beginners, it's essential to develop a step-by-step approach when dealing with complex expressions. Start from the innermost parentheses, apply the arithmetic operators according to their precedence, and work your way out to the overall expression.

For example, to evaluate the expression \(3 * 9 * (3 + (9 * 3 / 3)))\), you begin with the innermost calculation \(9 * 3 / 3\), then move outward, step by step until you reach the final multiplication that results in the expression's value. Such a systematic approach prevents errors and fosters a deeper understanding of how Java handles arithmetic calculations. Being meticulous with each step can dramatically improve the accuracy of your computations.