What does compilation mean in java

The compilation process in Java includes: lexical analysis, syntax analysis, semantic analysis, bytecode generation and class file generation. The compiled bytecode is a platform-independent instruction set that can be executed on any system that supports the Java Virtual Machine (JVM). It has the advantages of fast speed, high security, and strong portability, but there are also compilation problems. Disadvantages of long time and poor debuggability.

Compilation in Java

What is compilation?
In Java, compilation refers to the process of converting human-readable Java source code (.java) into machine-executable bytecode (.class).

Compilation process
The Java compiler javac takes Java source code as input and performs the following steps:

1. Lexical analysis: Break source code into smaller units called lexemes, such as identifiers, keywords, and punctuation marks.
2. Grammar analysis: Verify whether the result of lexical analysis complies with Java grammar rules.
3. Semantic analysis: Check whether the logic and semantics of the code are valid, such as variable declaration, type checking and method overloading.
4. Bytecode generation: Convert semantically analyzed code into bytecode that can be interpreted by the Java Virtual Machine (JVM).
5. Class file generation: Package the bytecode into a container called a class file (.class).

Compiled Bytecode
Compiled Bytecode is a platform-independent instruction set that can be executed on any system that supports JVM. The JVM loads the class file and interprets the bytecode, converting it into native machine instructions.

Advantages

• Speed: Compiled code executes faster than interpreted code.
• Security: The compiler will verify the validity of the code, thereby reducing security vulnerabilities.
• Portability: The bytecode can be executed on any system that supports JVM without recompilation.

Disadvantages

• Compilation time: Compilation usually takes longer than interpretation.
• Debuggability: Compiled code is more difficult to debug than interpreted code.

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