下面分析一下元空间、堆、线程在内存中的联系

        以下面代码为例

public class HelloWorld {
	
	private String name;
	
	public void sayHello() {
		System.out.println(name);
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public static void main(String[] args) {
		int a = 1;
		HelloWorld hw = new HelloWorld();
		hw.setName("test");
		hw.sayHello();
	}
}

        让我们来反编译下HelloWorld.class文件

C:\Users\Administrator\Desktop>javac HelloWorld.java

C:\Users\Administrator\Desktop>javap -verbose HelloWorld
Classfile /C:/Users/Administrator/Desktop/HelloWorld.class
  Last modified 2019-8-18; size 635 bytes
  MD5 checksum cf6b1e8b7a93a33de46deafdde7503c9
  Compiled from "HelloWorld.java"
public class HelloWorld
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #10.#24        // java/lang/Object."<init>":()V
   #2 = Fieldref           #25.#26        // java/lang/System.out:Ljava/io/PrintStream;
   #3 = Fieldref           #5.#27         // HelloWorld.name:Ljava/lang/String;
   #4 = Methodref          #28.#29        // java/io/PrintStream.println:(Ljava/lang/String;)V
   #5 = Class              #30            // HelloWorld
   #6 = Methodref          #5.#24         // HelloWorld."<init>":()V
   #7 = String             #31            // haha
   #8 = Methodref          #5.#32         // HelloWorld.setName:(Ljava/lang/String;)V
   #9 = Methodref          #5.#33         // HelloWorld.sayHello:()V
  #10 = Class              #34            // java/lang/Object
  #11 = Utf8               name
  #12 = Utf8               Ljava/lang/String;
  #13 = Utf8               <init>
  #14 = Utf8               ()V
  #15 = Utf8               Code
  #16 = Utf8               LineNumberTable
  #17 = Utf8               sayHello
  #18 = Utf8               setName
  #19 = Utf8               (Ljava/lang/String;)V
  #20 = Utf8               main
  #21 = Utf8               ([Ljava/lang/String;)V
  #22 = Utf8               SourceFile
  #23 = Utf8               HelloWorld.java
  #24 = NameAndType        #13:#14        // "<init>":()V
  #25 = Class              #35            // java/lang/System
  #26 = NameAndType        #36:#37        // out:Ljava/io/PrintStream;
  #27 = NameAndType        #11:#12        // name:Ljava/lang/String;
  #28 = Class              #38            // java/io/PrintStream
  #29 = NameAndType        #39:#19        // println:(Ljava/lang/String;)V
  #30 = Utf8               HelloWorld
  #31 = Utf8               haha
  #32 = NameAndType        #18:#19        // setName:(Ljava/lang/String;)V
  #33 = NameAndType        #17:#14        // sayHello:()V
  #34 = Utf8               java/lang/Object
  #35 = Utf8               java/lang/System
  #36 = Utf8               out
  #37 = Utf8               Ljava/io/PrintStream;
  #38 = Utf8               java/io/PrintStream
  #39 = Utf8               println
{
  public HelloWorld();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 1: 0

  public void sayHello();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream
         3: aload_0
         4: getfield      #3                  // Field name:Ljava/lang/String;
         7: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/
        10: return
      LineNumberTable:
        line 6: 0
        line 7: 10

  public void setName(java.lang.String);
    descriptor: (Ljava/lang/String;)V
    flags: ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
         0: aload_0
         1: aload_1
         2: putfield      #3                  // Field name:Ljava/lang/String;
         5: return
      LineNumberTable:
        line 10: 0
        line 11: 5

  public static void main(java.lang.String[]);
    descriptor: ([Ljava/lang/String;)V
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=3, args_size=1
         0: iconst_1
         1: istore_1
         2: new           #5                  // class HelloWorld
         5: dup
         6: invokespecial #6                  // Method "<init>":()V
         9: astore_2
        10: aload_2
        11: ldc           #7                  // String haha
        13: invokevirtual #8                  // Method setName:(Ljava/lang/String;)V
        16: aload_2
        17: invokevirtual #9                  // Method sayHello:()V
        20: return
      LineNumberTable:
        line 14: 0
        line 15: 2
        line 16: 10
        line 17: 16
        line 18: 20
}
SourceFile: "HelloWorld.java"