Java First axis

What is the role of the JVM?

The computer language can only recognize binary codes such as 0 and 1. And the code we write is not binary code. This is the time to need an interpreter, the translator called the compiler. (Compiler). Java compiler commands are called Javac but each platform has a different order of interpretation for binary codes such as 0 and 1, so the program cannot be compiled once and runs correctly on all platforms. javac . Java source files, compiled into a . class executable file. The . Class executable can only be run on a machine with a JVM installed. Different platform JVMs are not the same. The JVM can translate the. class file into the machine code of the corresponding platform.

Eclipse Common shortcut keys: (Control and Command key, depending on the computer settings are different)

1, Alt +? or alt+/: Auto-complete code or prompt code. 2, Control/command + O: Quick outline view. 3, Control/command + shift + R: Opens a list of resources. 4, Control/command + shift + F: Format code. 5, Control/command + E: Quick Convert editor. 6, Control/command + PAGE Down ([) or Control/command + PAGE Up (]): Quickly switch between tabs. 7, shift + Enter and CTRL + shift + ENTER: Create white space below or above the current line. 8, Alt + arrow key up and down: The next line to exchange content or the current line content to move up or down. 9, Control/command + Alt + direction: Copy the highlighted row or lines. 10, Control/command + M: Maximize the current edit page window. 11, Control/command +/: Automatically comment on the current line or select multiple lines. 12, Control/command + D: Delete the current line. 13, Control/command + shift + O: Automatically introduce packages and delete useless packets.

What is a JDK?

is the Free Software Development Kit (Sdk,software Development Kit) released by the solar Micro system for Java developers. The JDK is the core of the entire Java, including the Java Runtime Environment, Java tools, and the Java base Class library. The 2006 Solar Micro system announced the release of the GPL-based open source JDK, making the JDK a free software.
What is the JRE?
A collection of environments necessary to run a Java program, including the JVM standard implementation and the Java Core Class library.
What are the features of the Java language?

Simplicity, object-oriented, distributed, interpreted, reliable, secure, platform-independent, portable, high-performance, multi-line
process, dynamic, etc.

Common terminal commands

1. PWD Displays the current directory path 2. LS Lists all 3. CD path into directory 4. CD: Return to the upper directory 5. cd ~ Return to root directory 6. mkdir dirName Create folder 7. Open. Open the current directory 8. rmdir dirName Delete file 9. Open filename Opens the file. Touch filename Creates a file one by one. vim edit file. vi Create file and Edit RM fileName Delete file

Java First axis