How Java Runs
How a Java program runs: what javac produces, what the java command and the JVM do with it, and why one build runs on every machine.
What happens between writing a Java file and seeing its output. Java translates your code twice: the javac command turns the text into bytecode, an instruction set no real processor runs, and the java command starts the Java Virtual Machine, which runs that bytecode on the machine in front of it. It covers the two translations, the two commands, why the same jar runs on any operating system, the difference between the JDK, the JRE and the JVM, and the entry point the launcher looks for. It leaves out class loading and just-in-time compilation, which you can go years without.
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