java

Overview

References

https://docs.oracle.com/javase/8/docs/

Common

• Why java is cross-platform

Linux: ELF

> file /usr/bin/kubectl        
/usr/bin/kubectl: ELF 64-bit LSB executable

MacOS: Mach-O

> file /usr/local/bin/kubectl
/usr/local/bin/kubectl: Mach-O 64-bit executable x86_64

Lifecycle

compile -> class loading -> runtime

Compile

• how to compile .java files
  javac

• how to co mpile .java files if there are 3rd depnendencies
  javac -cp

• how to view the bytecode
  javap

ClassLoader

• how to define class loader
  Class loadClass(String name)
  Class findClass(String name)
  Class defineClass(byte[] code, String name)

• loading linking initializating
  J2SE doc
  JVM architecture

• java class initialization sequenct
  parent static field/code block (only once)
  static field/code block (only once )
  parent field/code block
  parent constructor
  field/code block
  constructor

Runtime

• jvm components heap
  vm stack
  native method stack
  Method area
  class information
  bytecode of methods and constructors
  runtime constant pool
  pc

• how to monitor jvm
  jstat visualvm ...

Test

JUnit