Why is JAVA popular

Different computer hardware and software environments on the Internet require a cross-platform language.

JAVA core advantage: Cross-platform

The JVM virtual machine

The JVM (JAVA VIRTUAL MACHINE) is a specification that can be implemented using either software or hardware; it is a VIRTUAL computer that executes Bytecodes. He also defines instruction sets, register sets, structural stacks, garbage collection heaps, and memory areas.

A JVM is a computer that is simulated by software or hardware on a computer, similar to a small and efficient CPU.

Java virtual machine is the core technology of Java and the foundation of cross-platform. You can use software, such as IBM, SUN, BEA, etc. Of course, you can also write a JVM, you can use hardware to implement, such as SUM/Intel is developing the Java chip

JVM and JAVA cross-platform features

The types of high-level computer programming languages are generally compiled and interpreted. The Java language is a combination of both types.

Compiled: First translate the entire English article into Chinese, and then read it.

Pros: Efficient reading.

Disadvantages: Need to wait for English teacher to translate English articles before reading.

The English teacher read us line by line advantage: there is no need to wait before reading

Disadvantages: Inefficient reading Common Java programs are written and executed in the following steps:

  1. Through the editor to write Java source program source file (source file name. Java).
  2. The compiler compiles the source program into a bytecode file (class name.class).
  3. Bytecode files are interpreted into the corresponding machine language by the interpreter and run (bytecode files are run in the JVM).

The above picture is a JAVA file compiled into a class file and the class bytecode file executed on different devices. VMS can be installed on different devices to achieve cross-platform and portable functions.

JAVA and C language cross-platform principle comparison

Java: Compile once, run anywhere

What the Java compiler does: Compiles, which compiles a source file into a bytecode file.

What the Java Virtual machine does: interpret, translate bytecode files into the machine language of the platform.

C: Compile multiple times, run everywhere