Syntax Basics

Literals

Integer Literals

Format	Example	Description
Decimal	`42`	Base 10
Hexadecimal	`0x2A`	Base 16, prefix 0x
Binary	`0b101010`	Base 2, prefix 0b
Octal	`052`	Base 8, prefix 0
Long	`42L`	64-bit with L suffix
Underscores	`1_000_000`	Readability separators

Floating-Point Literals

Format	Example	Description
Double	`3.14`	64-bit (default)
Float	`3.14f`	32-bit with f suffix
Scientific	`1.5e10`	Exponential notation

Character and String Literals

char c = 'A';
String s = "Hello, World!";

// Escape sequences
'\t'   // Tab
'\n'   // Newline
'\r'   // Carriage return
'\\'   // Backslash
'\''   // Single quote
'\"'   // Double quote
'\u0041'  // Unicode (A)

Text Blocks (Multi-line Strings)

String html = """
    <html>
        <body>Hello</body>
    </html>
    """;

Boolean and Null

boolean flag = true;
boolean other = false;
Object obj = null;

Keywords (58 total)

Type Keywords

Keyword	Description
`class`	Declare a class
`interface`	Declare an interface
`enum`	Declare an enumeration
`record`	Declare a record (Java 14+)
`extends`	Inherit from a class
`implements`	Implement interfaces

Primitive Types

Type	Size	Range
`byte`	8-bit	-128 to 127
`short`	16-bit	-32,768 to 32,767
`int`	32-bit	-2^31 to 2^31-1
`long`	64-bit	-2^63 to 2^63-1
`float`	32-bit	IEEE 754 floating-point
`double`	64-bit	IEEE 754 floating-point
`char`	16-bit	Unicode character
`boolean`	1-bit	true or false
`void`	-	No return value

Access Modifiers

Modifier	Description
`public`	Accessible from anywhere
`private`	Accessible only within the class
`protected`	Accessible within package and subclasses

Other Modifiers

Modifier	Description
`static`	Class-level member
`final`	Cannot be modified/overridden
`abstract`	No implementation provided
`synchronized`	Thread-safe access
`volatile`	Memory visibility guarantee
`transient`	Excluded from serialization
`native`	Implemented in native code
`sealed`	Restricted inheritance (Java 17+)
`non-sealed`	Allow further extension

Control Flow Keywords

if, else, for, while, do, switch, case, default, break, continue, return, yield

Exception Keywords

try, catch, finally, throw, throws

Other Keywords

new, this, super, instanceof, var, assert, package, import

Operators

Arithmetic Operators

Operator	Description	Example
`+`	Addition	`5 + 3` = 8
`-`	Subtraction	`5 - 3` = 2
`*`	Multiplication	`5 * 3` = 15
`/`	Division	`5 / 3` = 1
`%`	Modulo	`5 % 3` = 2

Comparison Operators

Operator	Description
`==`	Equal to
`!=`	Not equal to
`<`	Less than
`>`	Greater than
`<=`	Less than or equal
`>=`	Greater than or equal

Logical Operators

Operator	Description
`&&`	Logical AND (short-circuit)
`\|\|`	Logical OR (short-circuit)
`!`	Logical NOT

Bitwise Operators

Operator	Description
`&`	Bitwise AND
`\|`	Bitwise OR
`^`	Bitwise XOR
`~`	Bitwise NOT
`<<`	Left shift
`>>`	Signed right shift
`>>>`	Unsigned right shift

Assignment Operators

=, +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=, >>>=

Unary Operators

Operator	Description
`++x`	Pre-increment
`x++`	Post-increment
`--x`	Pre-decrement
`x--`	Post-decrement
`+x`	Unary plus
`-x`	Unary minus

Special Operators

Operator	Description	Example
`? :`	Ternary conditional	`x > 0 ? "positive" : "non-positive"`
`instanceof`	Type checking	`obj instanceof String`
`->`	Lambda arrow	`x -> x * 2`
`::`	Method reference	`String::length`

Operator Precedence

Precedence	Operators
1 (highest)	`() [] .`
2	`++ -- + - ! ~` (unary)
3	`* / %`
4	`+ -`
5	`<< >> >>>`
6	`< <= > >= instanceof`
7	`== !=`
8	`&`
9	`^`
10	`\|`
11	`&&`
12	`\|\|`
13	`? :`
14 (lowest)	`= += -= *= /= ...`

Comments

// Single-line comment

/* Multi-line
   comment */

/**
 * Documentation comment
 * @param x description
 * @return description
 */