Java has a fixed set of reserved words called keywords. These words have special meaning in the language and cannot be used as variable, method, or class names.

Think of them as the “grammar rules” Java uses to understand what you’re trying to do.

These keywords control how code runs:

• if, else – decision-making
• switch, case, default – multiple condition branching
• for, while, do – loops
• break, continue – exit or skip loop blocks
• return – exit a method and optionally send a value back

Used to define structure of programs:

• class, interface, enum, record – define types
• extends, implements , sealed – inheritance
• this, super – refer to current/parent object

Used to define visibility:

• public, private, protected – who can access
• static – belongs to class, not instance
• final – value can’t be changed or method/class can’t be overridden

• abstract – incomplete class or method
• synchronized – used in multithreading
• transient, volatile – used in serialization and memory control
• native – links to non-Java code (e.g., C)

• try, catch, finally, throw, throws – manage errors safely

• true, false, null – constants

• int, double, char, boolean, byte, short, long, float

Java has 50+ keywords, but you’ll become familiar with them naturally as you write more code. You don’t need to memorize them upfront—just recognize them and avoid using them for names.