Java字节码中的#Number是什么？ [重复]

This question already has an answer here:

这个问题在这里已有答案：

Reading a Java bytecode instruction: What does the number mean? 2 answers
读取Java字节码指令：数字是什么意思？ 2个答案

I wrote a simple java source like this :

我写了一个简单的java源代码：

public class Main {    
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

and converted it to the equivalent bytecode with the javap -c command

并使用javap -c命令将其转换为等效的字节码

Compiled from "Main.java"
public class Main {
  public Main();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method java/lang/Object."<init>":()V
       4: return

  public static void main(java.lang.String[]);
    Code:
       0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
       3: ldc           #3                  // String Hello World!
       5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
       8: return
}

What are #1,#2,#3,#4,... ?

什么是＃1，＃2，＃3，＃4，......？

When and Why would you use it ?

何时以及为何使用它？

2 个解决方案

#1

Those # symbols refer to the constant pool of the class, if you decompile verbosely using

如果你使用verbosely反编译，那些＃符号引用类的常量池

javap -c -s -verbose Main.class

you will get their definition in the Constant pool section

您将在常量池部分中获得它们的定义

Constant pool:
 #1 = Methodref          #6.#15         // java/lang/Object."<init>"()V
 #2 = Fieldref           #16.#17        //  
 = String             #18            // Hello World!
#4 = Methodref          #19.#20        // java/io/PrintStream.println:(Ljava/lang/String;)V
#5 = Class              #21            // Main
#6 = Class              #22            // java/lang/Object
#7 = Utf8               <init>
#8 = Utf8               ()V
#9 = Utf8               Code
#10 = Utf8               LineNumberTable
#11 = Utf8               main 
...

#2

The #x refers to an entry in the class constant pool. The actual value of the entry is printed in the comment.

#x引用类常量池中的条目。条目的实际值将打印在注释中。

To also view the constant pool use javap -c -verbose ...

要查看常量池，请使用javap -c -verbose ...

#1