Basics of Java 2

1. Operation of the folder

Dir: Displays all files and folders in the current folder.

CD path: Enter to the specified path.

Cd.. : Go back to the top level directory

CD \: Back to the current directory with the directory

MD folder name Create a folder

Rd Folder name Delete Folder action

2. Operation of the file

echo data (content) > file name Create a file and specify the data.

Type file name to view the contents of the specified file

Del file name deletes the specified file

* Wildcard Characters

Tab fill Content

CLS Clear Screen

Up and DOWN ARROW keys to retrieve the last written content

Exit close the console.

3.java Important Features: (1). Cross-platform (operating system). (2). Open source

4. What is cross-platform: once compiled, run everywhere.

5.Java Virtual machine cross-platform?

No cross-platform, just a broker: Let this java instruction be recognized by the operating system.

6.jre:java the operating environment.

Jdk:java development tool Set

One.. Identifier

1. In Java programs some names can be defined by themselves, then these custom names we call him a custom identifier.

2. System default identifiers: Keywords and reserved words

3. Identifier Naming NOTE:

(1). The constituent elements of an identifier can only be by letter (a-za-z), Number (0-9), underscore _, dollar sign ($)

(2). Cannot start with a number

(3). Strictly Case-sensitive

(4). Cannot be named with keywords and reserved words.

(5). Identifier name is not limited in length

(6). The name of the identifier should be meaningful.

4. Naming conventions for identifiers:

(1). The first letter of the class name and interface list Word, the other lowercase

(2). The name of the variable and the name of the method the first letter is lowercase, the first letter of the other word is capitalized, and the other is lowercase.

(3). Package name All words lowercase

(4). Constant all words capitalized words and words are separated by underscores such as: pi_2

Two Keywords: identifiers with special meanings in Java, called keyword keywords, are typically used to describe the structure of a program and the types of variables

Basics of Java 2