Think of the departures screen at an airport, the app that shows your bank balance, or the server that answers when you buy a train ticket. A great deal of that software is written in Java. Every piece of it began as plain text in a file. Someone typed instructions in a language people can read, and a tool turned the text into something a computer could carry out. This course teaches you to write that text in Java and to use the same tools professionals use to turn it into working software.
No programming experience is assumed. This chapter covers the three things every later page takes for granted.
The first section separates the text you write, called source code, from the tool that translates it, the compiler. You then read a short Java program, predict what it prints line by line, and meet the two mistakes that catch almost everyone on their first day.
The second section covers how files are named and stored, and the text window where you type instructions to the computer instead of clicking. In Chapter 1 you will install Java and run your first program from that window, in a place you set up here. Tell the course your operating system once, and every set of instructions follows your choice.
The third section explains how the course works. It covers the two ways each idea is explained and the labels that mark how new a feature is. It also covers the asides about older code you will meet at work, and what the exercises do with the code you type. It also explains why every output shown on a page was really produced by Java.
By the end you'll have a place ready for your first .java file, and a clear picture of what happens to the text you type into it.