Java 9 Programming By Example

Looking at the byte code

The class file is a binary file. The main role of this format is to be executed by the JVM and to provide symbolic information for the Java compiler when a code uses some of the classes from a library. When we compile our program that contains System.out.println, the compiler looks at the compiled .class files and not at the source code. It has to find the class named System, the field named out, and the method println. When we debug a piece of code or try to find out why a program does not find a class or method, we will need a way to look into the binary of the .class files. This is not an everyday task and it takes some advanced knowledge

To do so, there is a decompiler that can display the content of a .class ...