The use of the term 'compilation' with computer programs means 'translation' from the source code we write to a form that can be executed.

There are several implementations of java compiler and tools.

I will describe the tools from Sun's SDK (software development kit).

The compiler is a program javac.

Java programs should be written and saved in in files with extent .java such as Hello.java.

This file is compiled with the javac compiler:

      javac Hello.java
   

The result is a new file named Hello.class

The Hello.class file is not a text file (it isn't composed of 'lines' of text), but it also doesn't contain machine code.

It contains an intermediate form of code called java byte code.