Identifier: Java character sequence used when a variety of variables, methods and classes and other factors designation as an identifier. (Who named the place they can call identifier, follow the rules for identifiers)
the Java naming convention:
1, identified by the letters, underscore "_" dollar sign "$" or numbers;
2, should identifier underlined letter beginning, the dollar sign;
3, Java identifiers are case sensitive, unlimited length;
4, select Java identifier should be noted that "knowingly intended to see" and not with the Java language keywords the same name (the convention)
Legal identifier
the HelloWorld
DataClass
983
$ bS5_c7
Not legal identifier
class
DataClass #
98.3
Hell World
Keywords: Java some special meaning given, with a string special purposes are called keywords (keyword) (most editors will be marked with a special key way)
all the Java keywords are lowercase English
goto and const though never used, but also retained as Java keywords
| category | Keyword | Explanation |
|---|---|---|
| Access control | private | private |
| protected | under protection | |
| public | public | |
| Class, method and variable modifiers | abstract | Abstract statement |
| class | class | |
| extends | Yun expansion, succession | |
| final | The final value can not be changed | |
| implements | Implement (Interface) | |
| interface | interface | |
| native | Local, native method (non-Java implementation) | |
| new | New, created | |
| static | Static state | |
| strictfp | Strict, precise | |
| synchronized | Threads, synchronization | |
| transient | short | |
| volatile | Volatile | |
| Program control statements | break | Out of the loop |
| case | Define a value for switch selection | |
| continue | carry on | |
| default | default | |
| do | run | |
| else | otherwise | |
| for | cycle | |
| if | in case | |
| instanceof | Examples | |
| return | return | |
| switch | Execution based on the value selected | |
| while | cycle | |
| Error Handling | assert | Whether the assertion expression is true |
| catch | Catch an Exception | |
| finally | There are no exceptions to perform | |
| throw | Throw an exception object | |
| throws | Declare an exception might be thrown | |
| try | Catch the exception | |
| Package Dependencies | import | Introduced |
| package | package | |
| basic type | boolean | Boolean |
| byte | Byte | |
| char | Character | |
| double | Double-precision floating point | |
| float | Single-precision floating point | |
| int | Integer | |
| long | Long integer | |
| short | Short integer | |
| null | air | |
| Variable reference | super | The parent class, the superclass |
| this | This class | |
| void | No return value | |
| Reserved Keywords | goto | Keyword, but you can not use |
| const | Keyword, but you can not use |
Java constants: string identifier, to distinguish between different types of data.
A constant integer: 123
real constant: 3.14
character constant: 'a'
logical constants: true, false
string constants: "HelloWord"
Note: distinguishing character constants and string literals;
Note: "constant" term will be used; Also other contexts immutable value of the variable, see the final keyword