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)
true |
false |
null |
Delimiter | Meaning |
/** | Begin documentation comment |
/* | Begin indefinite comment |
*/ | End indefinite comment |
// | Comment to end of line |
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 |
Numeric Format and Range | Meaning |
\0 through \377 | Octal value of character (<= \u00FF) |
\u0000 through \uFFFF | Unicode hexadecimal value of character |
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. |
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 |
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.
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> |