白桃乌龙

I think ,therefore I am.

Java Take-Home-Message

bytecode 字节码

pros: A compromise between target machine code and interpreter solution: 1.VM-oriented:(Architecture neutral(中立)) offers a good cross-platform compatibility. 2. speed: machine-code > bytecode > inteprete

techs gradually developed base on bytecode :

  1. cache for hot code ->machine code ,(hot means conde snippets use more often) -> JIT
  2. all compiled machine-code ->AOT ,but machine-code quality less good (than what ?maybe lack of optimize?)

concepts recall: compiled type: compile all file to machine-code. like DB field materialized-model procedure. interpreted type: compile and run line by line . like DB field volcano-model. ![[Pasted image 20230708095334.png]]

Reflection 反射

concept: let any code snippets get any object`s data structure and functions. base on this , can we somehow dynamically let program user create a class at running time ?

Serialize 序列化

serialize concepts: convert an object to byte-sequence or convert an object to JSON,XML….. deserialize : commonly , convert a JSON to an object.

usage: 1.cross-programming-laguage procedure call. (RPC) 2.network transport 3.create object from IO(disk,network) todo: whats the basic impl of serialize ? to what kind of byte-sequence? anything could be called byte-sequence.

impl: whats the binary view of an object and JSON ? the encoder and decoder view of this. what serialize did?

Code-Robustness : Exception

Throwable:
Error:
VM-Error:
Stack Overflow
Out of Memory
Exception:
IO Exception:
EOF(End Of File) 文件越界
FileNotFound
NotHavePermission (R or W or R\W)
RuntimeException:
Arithmetic
ClassNotFound
IllegalArgument
ArrayIndexOutOfBound
UnknownType
NullPointer

Multi-Thread Communication

Basic Approach:
Mutex: 互斥锁
实现:syncronized 关键词

Java file IO

Java network IO

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