Javac vs. Eclipse Compiler: Wrapper or Unique Entity, and Why Does Eclipse Use Its Own?

Understanding the Distinction Between javac and Eclipse Compiler

The Java programming language is famously known for its compile-once, run-anywhere principle. This entails that code written in Java is first compiled into an intermediate form, known as bytecode, before execution on a Java Virtual Machine (JVM). Amid the various Java compilers available, javac and Eclipse compiler stand out.

Is Eclipse's Compiler a Wrapper or a Unique Entity?

Unlike the javac compiler, which is part of the Sun Java Developer Kit (JDK), Eclipse employs a distinct compiler named Eclipse Compiler for Java (ECJ). ECJ is not a mere wrapper around javac's core; it is an independent compiler developed by the Eclipse Foundation. This distinction raises the question of why Eclipse chose to create a separate compiler rather than rely on the established javac.

Distinctive Features of ECJ

ECJ offers several unique features that distinguish it from javac. One notable difference is its ability to execute code that contains errors. If the problematic code block is not invoked during runtime, the program may run successfully. However, if the block is executed, an exception will be thrown, indicating an attempt to run incompliant code. In contrast, javac strictly disallows the execution of code with any errors.

Furthermore, ECJ enables incremental builds within the Eclipse Integrated Development Environment (IDE). As soon as you complete typing, ECJ compiles the code, providing immediate feedback and reducing compilation time. This feature is particularly beneficial for rapid development and debugging.

Eclipse's Compiler Integration

The decision to integrate ECJ into Eclipse has practical implications. You can develop, compile, and execute Java code in Eclipse without the necessity of installing the JDK. This portability enhances productivity, especially in environments where access to the JDK is limited.

Real-World Applications of ECJ

The popularity of ECJ extends beyond the Eclipse IDE. It has found traction in various applications, including:

• Apache Tomcat for compiling Java Server Pages (JSPs)
• IntelliJ IDEA as a compatible compiler
• GNU Compiler for Java (GCJ) for seamless integration
• Liferay as its build compiler

Ultimately, the utilization of ECJ or javac depends on specific requirements and preferences. While javac remains the standard compiler for JDK, ECJ offers unique advantages for incremental builds, error handling, and IDE integration.

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