"Java would become easier for students to learn under
a proposal to introduce flexible main methods and anonymous main classes to the language,"
reports InfoWorld.
Details of the plan include enhancing the protocol by which Java programs are launched to be flexible, in particular to allow the String[] parameter of main methods to be omitted and allow main methods to be neither public nor static; the Hello World program would be simplified. Anonymous main classes would be introduced to make the class declaration implicit.
It's currently a disabled-by-default preview language feature in JDK 21 (scheduled for General Availability in September), included to provoke developer feedback based on real world use (which
may lead to it becoming permanent in the future). This wouldn't introduce a separate beginner's dialect or beginners' toolchain of Java, emphasizes
Java Enhancement Proposal (JEP) 445. "Student programs should be compiled and run with the same tools that compile and run any Java program."
But it argues that a simple "Hello World" program today has "too much clutter...too much code, too many concepts, too many constructs — for what the program does."
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
Anonymous main classes would make the public
class declaration implicit (while also sparing newbies the "mysterious" modifier
static and the args parameter
String[] ). The program is streamlined to:
void main() {
System.out.println("Hello, World!");
}
The proposal argues this change reduces "the ceremony of writing simple programs such as scripts and command-line utilities." And since Java is intended to be a first programming language, this change would mean students "can write their first programs without needing to understand language features designed for large programs," using instead "streamlined declarations for single-class programs". (This allows students and educators to explore language features more gradually.)
A Hello, World! program written as an anonymous main class is much more focused on what the program actually does, omitting concepts and constructs it does not need. Even so, all members are interpreted just as they are in an ordinary class. To evolve an anonymous main class into an ordinary class, all we need to do is wrap its declaration, excluding import statements, inside an explicit class declaration.
