Note that I didn’t use the mkdir to create an output directory, because in JDK 16 the option -d already do this to us.
Compiling in JDK 16 $ javac src/com/examples/javacodegeeks/compiler/JavaCompilerExample.java -d out Now, let’s execute our compiled code using the java command: Running application $ cd out Note that I use a bash command just to create an output directory for the compiler uses to generate the bytecode file (.class). $ javac src/com/examples/javacodegeeks/compiler/JavaCompilerExample.java -d out Moving on, in the root directory of our project, we use the command below in JDK 8 to compile the previous source code. For this article, I create a simple code to be compiled, the famous “Hello world” script to show us how the compiler works. Now, with our Java version defined, let’s compile our code. However, for this article, I’ll show some little difference between compilers in JDK 1.8 and JDK 16. Why did I put this information? The Java compiler command remains (almost) the same through the very first version (1.0) until the most recently (16). OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing) OpenJDK Runtime Environment (build 16+36-2231) If you’re using the JDK 16, the same command will show the version as well. Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode) Java(TM) SE Runtime Environment (build 1.8.0_181-b13) But, for studies purposes, we’ll use the terminal to compile and run our application to understand how the compiler works in the Java environment.įirst, let’s check what’s our Java version installed: Checking JDK version $ java -version IDE’s like IntelliJ have already an embedded way to compile and execute our application. Important note: while javac is the command to convert source code into bytecode, the java command in JDK is used by the JVM to effectively run our application. To check the compiler version after installing JDK into our machine, let’s use the command below: Check javac version $ javac -version It comes with the JDK installation in both versions (Oracle and OpenJDK). The official Java compiler is called javac. Also, the compiler will analyze the source code syntax to make sure that the statements written by the developer are correctly referred to in the final bytecode. As said before, we use a compiler to convert our source code into machine language, the bytecodes.
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