What java command/binary uses for printing out the readable java bytecode?

Use the javap command, for example:

javap -v SomeClass.class

Example output:

19:23:56 (brettw) [dev] hikari$ javap -v HikariPool.class
Classfile /Users/brettw/Documents/dev/HikariCP/core/target/classes/com/zaxxer/hikari/HikariPool.class
Last modified Dec 19, 2013; size 11754 bytes
MD5 checksum 00e0441d0aad3bad1f4e7a67f6043b9c
Compiled from "HikariPool.java"
public final class com.zaxxer.hikari.HikariPool implements com.zaxxer.hikari.HikariPoolMBean
  SourceFile: "HikariPool.java"
  InnerClasses:
     #384; //class com/zaxxer/hikari/HikariPool$1
minor version: 0
major version: 51
flags: ACC_PUBLIC, ACC_FINAL, ACC_SUPER
Constant pool:
#1 = Class              #2            //  com/zaxxer/hikari/HikariPool
#2 = Utf8               com/zaxxer/hikari/HikariPool
#3 = Class              #4            //  java/lang/Object
#4 = Utf8               java/lang/Object
#5 = Class              #6            //  com/zaxxer/hikari/HikariPoolMBean
#6 = Utf8               com/zaxxer/hikari/HikariPoolMBean
...