D:\java\test\out\production\test>javap -verbose mainTest

 Classfile /D:/java/test/out/production/test/mainTest.class

   Last modified 2019年4月22日; size  bytes

   MD5 checksum 08699c6d713bc8967a8daea381ce23c1

   Compiled from "mainTest.java"

 public class mainTest

   minor version:

   major version:

   flags: (0x0021) ACC_PUBLIC, ACC_SUPER

   this_class: #                          // mainTest

   super_class: #                         // java/lang/Object

   interfaces: , fields: , methods: , attributes:

 Constant pool:

    # = Methodref          #.#         // java/lang/Object."<init>":()V

    # = Fieldref           #.#         // mainTest.age2:I

    # = String             #            // sss

    # = Class              #            // mainTest

    # = Class              #            // java/lang/Object

    # = Utf8               age2

    # = Utf8               I

    # = Utf8               <init>

    # = Utf8               ()V

   # = Utf8               Code

   # = Utf8               LineNumberTable

   # = Utf8               LocalVariableTable

   # = Utf8               this

   # = Utf8               LmainTest;

   # = Utf8               main

   # = Utf8               ([Ljava/lang/String;)V

   # = Utf8               args

   # = Utf8               [Ljava/lang/String;

   # = Utf8               name

   # = Utf8               Ljava/lang/String;

   # = Utf8               nick

   # = Utf8               age

   # = Utf8               SourceFile

   # = Utf8               mainTest.java

   # = NameAndType        #:#          // "<init>":()V

   # = NameAndType        #:#          // age2:I

   # = Utf8               sss

   # = Utf8               mainTest

   # = Utf8               java/lang/Object

 {

   public mainTest();

     descriptor: ()V

     flags: (0x0001) ACC_PUBLIC

     Code:

       stack=, locals=, args_size=

          : aload_0

          : invokespecial #                  // Method java/lang/Object."<init>":()V

          : aload_0

          : bipush

          : putfield      #                  // Field age2:I

         : return

       LineNumberTable:

         line :

         line :

       LocalVariableTable:

         Start  Length  Slot  Name   Signature

                          this   LmainTest;

   public static void main(java.lang.String[]);

     descriptor: ([Ljava/lang/String;)V

     flags: (0x0009) ACC_PUBLIC, ACC_STATIC

     Code:

       stack=, locals=, args_size=

          : ldc           #                  // String sss

          : astore_1

          : ldc           #                  // String sss

          : astore_2

          : bipush

          : istore_3

          : return

       LineNumberTable:

         line :

         line :

         line :

         line :

       LocalVariableTable:

         Start  Length  Slot  Name   Signature

                          args   [Ljava/lang/String;

                           name   Ljava/lang/String;

                           nick   Ljava/lang/String;

                            age   I

 }

 SourceFile: "mainTest.java"