java .build

Java .build

Introduction

In the world of software development, build automation plays a crucial role. It helps streamline the process of compiling, testing, and packaging code, making it easier for developers to build and deploy their applications. Java, being one of the most widely used programming languages, has its own build automation tool called javac. In this article, we will explore the java .build command and how it can be used to automate the build process in Java.

What is java .build?

java .build is a command-line tool provided by the Java Development Kit (JDK) to automate the build process for Java applications. It leverages the power of the Java javac compiler and other build-related tools to compile, test, and package Java code.

Setting up the Project

Before we dive into the java .build command, let's set up a sample Java project. For this example, let's create a simple calculator application with the following directory structure:

calculator/
  src/
    com/
      example/
        Calculator.java
  tests/
    com/
      example/
        CalculatorTest.java
  lib/
    junit.jar
  build/

The src/ directory contains the source code of the application, while the tests/ directory contains the test code. The lib/ directory holds any external dependencies required by the project. Finally, the build/ directory will be used to store the compiled code and generated artifacts.

Creating the Build File

To use the java .build command, we need to create a build file called build.yaml in the project's root directory. This build file specifies the build targets, dependencies, and other build-related configurations. Let's create a simple build.yaml file for our calculator project:

targets:
  - name: compile
    description: Compiles the Java source code
    commands:
      - javac -d build src/com/example/Calculator.java
  - name: test
    description: Runs the unit tests
    commands:
      - javac -classpath lib/junit.jar -d build tests/com/example/CalculatorTest.java
      - java -classpath build:lib/junit.jar org.junit.runner.JUnitCore com.example.CalculatorTest
  - name: package
    description: Packages the application into a JAR file
    commands:
      - jar cvf build/calculator.jar -C build com

In the above build.yaml file, we have defined three build targets: compile, test, and package. Each target has a description and a list of commands to execute. The compile target compiles the Java source code, the test target runs the unit tests, and the package target packages the application into a JAR file.

Executing the Build

To execute the build, open a command prompt or terminal and navigate to the project's root directory. Run the following command:

java .build compile

This command will execute the compile target specified in the build.yaml file. The Java source code will be compiled, and the compiled classes will be placed in the build/ directory.

To execute the other targets, simply replace compile with test or package in the above command.

Automating the Build Process

Manually executing the build targets every time we make a change to the code is not practical. Thankfully, the java .build command allows us to automate the build process by watching for file changes and automatically executing the build targets when necessary.

To enable automatic builds, add the following configuration to the build.yaml file:

watch:
  - src/**/*.java
  - tests/**/*.java

The watch section specifies the files and directories to monitor for changes. In our case, we are monitoring all .java files in the src/ and tests/ directories. If any of these files change, the corresponding build targets will be executed automatically.

To start the automatic build process, run the following command:

java .build --watch compile

Now, whenever you make a change to the Java source code or unit tests, the build targets will be executed automatically.

Gantt Chart

Below is a Gantt chart representing the build process of our calculator project:

gantt
    dateFormat  YYYY-MM-DD
    title       Calculator Build Process
    axisFormat  %m-%d

    section Compilation
    Compile source code            :done,    des1, 2021-10-01, 2021-10-01
    Compile unit tests             :done,    des2, 2021-10-01, 2021-10-01

    section Testing
    Run unit tests                 :done,    des3, 2021-10-01, 2021-10-01

    section Packaging
    Package into JAR               :done,    des4, 2021-10-01, 2021-10-01

The Gantt chart visually represents the different stages of the build process, their durations, and dependencies.

Conclusion

In this article, we have