Appendix A: The Java Language

Reserved Words (Keywords)

abstract	double	int	super
boolean	else*	interface	switch*
break*	extends	long	synchronized*
byte	final	native	this
case*	finally	new*	throw**
catch**	float	package	throws
char	for*	private	transient***
class	goto***	protected	try**
const***	if*	public	void
continue*	implements	return*	volatile***
default*	import	short	while*
do*	instanceof	static

The above words are class or data declaration or identification, unless specified otherwise (see below).


  * normal flow control or object construction

 ** exception handling

*** reserved but ignored by Java 1.0.x compilers (italics indicate words with
    specified meanings to be supported in future versions of Java: see glossary)

Reserved Words (Literals)

true

false

null

Markings and Special Characters-Comment Delimiters

Delimiter	Meaning
/**	Begin documentation comment
/*	Begin indefinite comment
*/	End indefinite comment
//	Comment to end of line

Character Escape Sequences (for Use in char '' and string "" Literals)

Meaning	Literal representation	ASCII code (decimal)	ASCII code (hexadecimal)	Unicode
backspace	\b	8	08	\u0008
tab	\t	9	09	\u0009
new line	\n	10	0A	\u000A
form feed	\f	12	0C	\u000C
line return	\r	13	0D	\u000D
double quote	\"	34	22	\u0022
single quote	\'	39	27	\u0027
backslash	\\	92	5C	\u005C

Octal and Unicode Character Constant Formats

Numeric Format and Range	Meaning
\0 through \377	Octal value of character (<= \u00FF)
\u0000 through \uFFFF	Unicode hexadecimal value of character

Operators and Precedence Groups-from Highest to Lowest Precedence (Modifiable by Parentheses)

Group	Operator(s)	Meanings
Postfix operators	[]	array access
	.	member access, method invocation
	()	method application
	++	increment after current value return
	--	decrement after current value return
Prefix operators	++	increment before current value return
	--	decrement before current value return
	+	unary plus (redundant)
	-	unary minus (multiplies by -1)
	~	bitwise complement
	!	Boolean complement
Prefix constructives	new	invoke constructor
	(<type>)	cast to <type>
Multiplicatives	* / %
Additives	+ -
Bit manipulatives	>>> >> <<
Comparatives	< <= >= > instanceof	relative order class membership
Identities	== !=
bitwise/boolean AND	&
bitwise/boolean XOR	^
bitwise/boolean OR	\|
boolean conditional AND	&&
boolean conditional OR	\|\|
ternary conditional	?:
assignments	= *= /= %= += -= <<= >>= >>>= &= ^= \|=	(i) active assignments have semantics i = i <modifier> j: e.g., i += j denotes i = i + j (ii) multiple assignments are processed from right to left: e.g., a=b=c denotes a=(b=c). All other operators of equal precedence are processed from left to right.

Global Constants (Public Static Values)

Use of these values improves clarity of code and enhances compatibility with future versions of Java or with installations on new classes of hardware. Checking of values against constraints such as Integer.MAX_VALUE reduces the likelihood of uncaught exceptions. Defining your own public static constants is an effective practice when designing your own classes.

Partial Listing in Format Class.NAME

Boolean.FALSE	Event.KEY_ACTION	Event.WINDOW_MOVED
Boolean.TRUE	Event.KEY_ACTION_RELEASE	FileDialog.LOAD
Character.MAX_RADIX	Event.KEY_PRESS	FileDialog.SAVE
Character.MAX_VALUE	Event.KEY_RELEASE	Float.MAX_VALUE
Character.MIN_RADIX	Event.LEFT	Float.MIN_VALUE
Character.MIN_VALUE	Event.LIST_DESELECT	Float.NaN
Color.black	Event.LIST_SELECT	Float.NEGATIVE_INFINITY
Color.blue	Event.LOAD_FILE	Float.POSITIVE_INFINITY
Color.cyan	Event.LOST_FOCUS	FlowLayout.CENTER
Color.darkGray	Event.MOUSE_DOWN	FlowLayout.LEFT
Color.gray	Event.MOUSE_DRAG	FlowLayout.RIGHT
Color.green	Event.MOUSE_ENTER	Font.BOLD
Color.lightGray	Event.MOUSE_EXIT	Font.ITALIC
Color.magenta	Event.MOUSE_MOVE	Font.PLAIN
Color.orange	Event.MOUSE_UP	Integer.MAX_VALUE
Color.pink	Event.PGDN	Integer.MIN_VALUE
Color.red	Event.PGUP	Label.CENTER
Color.white	Event.RIGHT	Label.LEFT
Color.yellow	Event.SAVE_FILE	Label.RIGHT
Double.MAX_VALUE	Event.SCROLL_ABSOLUTE	Long.MAX_VALUE
Double.MIN_VALUE	Event.SCROLL_LINE_DOWN	Long.MIN_VALUE
Double.NaN	Event.SCROLL_LINE_UP	Math.E
Double.NEGATIVE_INFINITY	Event.SCROLL_PAGE_DOWN	Math.PI
Double.POSITIVE_INFINITY	Event.SCROLL_PAGE_UP	Scrollbar.HORIZONTAL
Event.ACTION_EVENT	Event.UP	Scrollbar.VERTICAL
Event.DOWN	Event.WINDOW_DEICONIFY	Thread.MAX_PRIORITY
Event.END	Event.WINDOW_DESTROY	Thread.MIN_PRIORITY
Event.GOT_FOCUS	Event.WINDOW_EXPOSE	Thread.NORM_PRIORITY
Event.HOME	Event.WINDOW_ICONIFY

The ASCII Character Set

In this 7-bit code, with possible values 0 through 127, the first 32 values (0 through 31 decimal, 00 though 1F hex) are used by control characters such as backspace (decimal 8), tab (decimal 9), and form feed (decimal 12).

These control codes, and others, have special literal representations that are tabulated elsewhere in this appendix. Those literal representations should be used for both clarity and correctness. For example, '\n' should be used for a line feed rather than the equivalent Unicode escape sequence, \u000a, since the latter will be translated into an actual line feed at an early stage in the processing of the source code file.

This means that the statement


System.out.println('\u000a');

will look to the compiler like


System.out.println('

');

and will produce several error messages. The statement


System.out.println('\n');

will behave as one would expect.

Other low-group codes, such as 22 ("synchronous idle"), are relics of an earlier generation of communications equipment. The assignment of code 127 to mean "deleted" reflects the use of punched cards and paper tape: In binary, this code consists of seven 1s, represented by punching out all seven possible holes, obscuring whatever was encoded before on that card or in that position on the tape.

The numeric digits, the uppercase letters, and the lowercase letters have the same numeric code values in the 7-bit ASCII, the 8-bit ISO-Latin-1, and the 16-bit Unicode schemes.

ASCII Character Set

Decimal	Hexadecimal	Character
32	20	<space>
33	21	!
34	22	"
35	23	#
36	24	$
37	25	%
38	26	&
39	27	'
40	28	(
41	29	)
42	2A	*
43	2B	+
44	2C	,
45	2D	-
46	2E	.
47	2F	/
48	30	0
49	31	1
50	32	2
51	33	3
52	34	4
53	35	5
54	36	6
55	37	7
56	38	8
57	39	9
58	3A	:
59	3B	;
60	3C	<
61	3D	=
62	3E	>
63	3F	?
64	40	@
65	41	A
66	42	B
67	43	C
68	44	D
69	45	E
70	46	F
71	47	G
72	48	H
73	49	I
74	4A	J
75	4B	K
76	4C	L
77	4D	M
78	4E	N
79	4F	O
80	50	P
81	51	Q
82	52	R
83	53	S
84	54	T
85	55	U
86	56	V
87	57	W
88	58	X
89	59	Y
90	5A	Z
91	5B	[
92	5C	\
93	5D	]
94	5E	^
95	5F	_
96	60	`
97	61	a
98	62	b
99	63	c
100	64	d
101	65	e
102	66	f
103	67	g
104	68	h
105	69	i
106	6A	j
107	6B	k
108	6C	l
109	6D	m
110	6E	n
111	6F	o
112	70	p
113	71	q
114	72	r
115	73	s
116	74	t
117	75	u
118	76	v
119	77	w
120	78	x
121	79	y
122	7A	z
123	7B	{
124	7C	\|
125	7D	}
126	7E	~
127	7F	<deleted>

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