Operator Precedence

Operator precedence defines the order in which operators are evaluated in an expression. When multiple operators appear in a single statement, Java follows a fixed priority hierarchy to decide which operation executes first. This topic is critical for avoiding logical bugs and is a frequent interview favorite.

Why Operator Precedence Matters

• Prevents ambiguous expression evaluation
• Avoids unexpected results
• Essential for writing correct conditions and calculations
• Helps understand complex expressions in legacy code

Basic Rule

Higher-precedence operators are evaluated before lower-precedence operators. If operators have the same precedence, Java uses associativity (left-to-right or right-to-left).

Operator Precedence Table (High → Low)

Common Precedence Examples

Arithmetic Precedence

int result = 10 + 5 * 2;
System.out.println(result); // 20
          

Why: * has higher precedence than +.

Using Parentheses to Change Order

int result = (10 + 5) * 2;
System.out.println(result); // 30
          

Relational vs Logical Precedence

int a = 10, b = 20, c = 30;
boolean result = a < b && b < c;
          

Evaluation Order:

• a < b
• b < c
• &&

Assignment Precedence (Right to Left)

int a, b, c;
a = b = c = 5;
          

Why: Assignment operators are evaluated right to left.

Ternary Operator Precedence

int x = 10;
int y = 20;
int max = (x > y) ? x : y;
          

Important: Ternary has lower precedence than most operators, but higher than assignment.

Unary Operator Precedence

int a = 5;
int b = ++a * 2;
          

Evaluation:

• ++a → 6
• 6 * 2 → 12

Tricky Interview Example

System.out.println(10 + 20 + "Java" + 30 + 40);
          

Evaluation:

• 10 + 20 → 30
• "30" + "Java" → "30Java"
• "30Java" + 30 + 40 → "30Java3040"

Best Practices (Real-Time Coding)

• Use parentheses for clarity
• Avoid overly complex expressions
• Never rely on precedence for readability
• Prefer clean, explicit logic

Common Beginner Mistakes

• Assuming left-to-right evaluation always applies
• Forgetting precedence between && and ||
• Writing unreadable chained expressions
• Ignoring parentheses in ternary logic

Interview-Ready Answers

Short Answer

Operator precedence determines the order in which operators are evaluated in an expression.

Detailed Answer

Java follows a predefined operator precedence hierarchy to evaluate expressions. Operators with higher precedence are executed before lower-precedence ones, and when precedence is equal, associativity rules determine the evaluation order.

Key Takeaway

Operator precedence ensures predictable expression evaluation. Always use parentheses for clarity, especially in conditions and calculations.