{"id":22,"date":"2020-11-25T17:30:43","date_gmt":"2020-11-25T22:30:43","guid":{"rendered":"https:\/\/www.alpharithms.com\/?p=22"},"modified":"2021-07-27T08:09:38","modified_gmt":"2021-07-27T12:09:38","slug":"compiling-multiple-java-files","status":"publish","type":"post","link":"https:\/\/www.alpharithms.com\/compiling-multiple-java-files-433017\/","title":{"rendered":"Compiling Multiple Java Files Using Javac + Console Redirection"},"content":{"rendered":"

Using the Java Langage Compiler (javac) to compile .java files from the command line is super simple. Even though javac comes with a large list of possible arguments to specify use, compiling multiple java files isn’t easily achieved without outside help\u2014unless you want to type them all out as cmd arguments each time!<\/p>\n

Example Project structure<\/h2>\n

To illustrate how to compile multiple files in a Java project using only the command prompt, javac<\/code>, and the file<\/code> command (unix\/linux), we’ll be working with the following example project directory structure:<\/p>\n

.\r\n\u2514\u2500\u2500 ExampleProject\/\r\n    \u2514\u2500\u2500 src\/\r\n        \u251c\u2500\u2500 ClassOne.java\r\n        \u251c\u2500\u2500 ClassTwo.java\r\n        \u2514\u2500\u2500 ClassThree.java<\/pre>\n
Step 1: Create a List of All Source Files<\/h2>\n
Javac accepts an argument for a file containing all command-line arguments. This functionality opens the door for all kinds of possibilities but for the context of this article, we’ll be using it to load all source files for compilation.<\/p>\n
On linux\/Unix machine, the following command (issued from the ExampleProject<\/code> directory) will search for all java source files and save them into a file names sources.txt:<\/p>\n
find -name \"*.java\" > sources.txt<\/code><\/p>\n
This command results in the creation of a new sources.txt<\/code> file in our ExampleProject directory which contains the following information:<\/p>\n
.\/src\/ClassOne.java\r\n.\/src\/ClassTwo.java\r\n.\/src\/ClassThree.java<\/pre>\n
Step 2: Compile Source Files<\/h2>\n
After the sources.txt file has been generated one need only rely on the default functionality of the javac compiler, by specifying that command-line arguments be read from a file. In this case, multiple source files will be read in.<\/p>\n
javac @sources.txt<\/code><\/p>\n
After this command, the project structure will look like the following:<\/p>\n
\u2514\u2500\u2500 ExampleProject\/\r\n    \u251c\u2500\u2500 sources.txt\r\n    \u2514\u2500\u2500 src\/\r\n        \u251c\u2500\u2500 ClassOne.java\r\n        \u251c\u2500\u2500 ClassTwo.java\r\n        \u251c\u2500\u2500 ClassThree.java\r\n        \u251c\u2500\u2500 ClassOne.class\r\n        \u251c\u2500\u2500 ClassTwo.class\r\n        \u2514\u2500\u2500 ClassThree.class<\/pre>\n
Pros vs. Cons<\/h2>\n
The benefits of this method of compiling multiple files with javac<\/code> are that it has no dependencies and is super fast. However, the major drawback here is that the sources.txt<\/code> file needs to be regenerated every time a new source file is created or renamed.<\/p>\n
Build Tool Options<\/h2>\n
Being that Java is a mature, enterprise-grade, well-supported programming language\u2014there’s plenty of automated build tools that can help with compilation. The most popular are as follows:<\/p>\n