Operators & Expressions

== compares identity (same object in memory) for references and raw value for primitives. .equals() compares logical content. Always use .equals() for objects.

No. A leading zero makes it an octal literal, and 9 is not a valid octal digit. Remove the leading zero to write decimal 9.

&& short-circuits (skips right side if left is false), & always evaluates both sides. For boolean logic use &&/||. For bit manipulation on integers use &/|.

Bitwise operators (&, |, ^, ~) operate on individual bits. Shift operators (<<, >>, >>>) move bits left or right. They are used for flags, permissions, hashing, and low-level optimization.

The ternary operator (condition ? a : b) returns a if the condition is true, b if false. It is a compact alternative to if-else for simple value selection.

Java has four loops: for (counter-based), for-each (collection iteration), while (pre-check), and do-while (post-check, runs at least once).

The switch statement executes code blocks and needs break. The switch expression (Java 14+) returns a value, uses arrows, has no fall-through, and must be exhaustive.

Math is a utility class with static methods for rounding, min/max, abs, power, safe overflow-checked arithmetic, and random numbers.

Java integer overflow wraps silently with no exception. Use Math.addExact() to throw on overflow, long for large values, and BigDecimal for money.