Using IDEA to build JDK source reading environment

Using IDEA to build JDK source reading environment

First create a new java basic project

Basic Directory

source

test test source code and entry

Prepare JDK source code

The path framed in the following figure is the storage location of jdk

Open the jdk directory, find src.zip, right click and unzip

After decompression, enter the src folder, select java, javax, org and paste it into the source directory of the project

Attention please! Do not copy the window system in IDEA, but copy it directly between folders as shown in the figure below.

The source code is ready

Remove Debug restrictions

Uncheck single step to enter the bottom class

Replace SourcePath

The original source code is protected and cannot be commented out, so it is replaced with the source code in the source directory of the project

Write test code

public class Test {
    public static void main(String[] args) {
       StringBuffer stringBuffer = new StringBuffer();
       stringBuffer.append("可变序列");
       stringBuffer.append("123456");

       System.out.println(stringBuffer.toString());
       System.out.println(stringBuffer);
    }
}

The output of the two sentences is the same, I want to explore what happened at the bottom

Make a breakpoint before printing out

Debug view the underlying source code

F7 single step into view

The 9th line of the above test code is a string, so print String directly, and then wrap

The 10th line of the above test code is passed an object, then println will automatically convert the object into a string, and then output, and finally wrap.

It is recommended to look at common modules first

package	description	Key class
lang	Basic syntax, packaging type	Basic types, reflection, annotations
useful	Basic tools	Common tools, JUC, atomic class, lock
I	Blocking io	Byte stream
nio	Non-blocking io
math	Basic mathematics, large numbers
time	Date, time
net	Telecommunication	socket etc.