Run a single file without compiling

Definition

Java 11 can run a .java file directly with java Hello.java. It compiles the file in memory and runs it, which is handy for small scripts and for learning.

Example code

One file, one command

// file: Hello.java
class Hello {
    public static void main(String[] args) {
        System.out.println("Hello from a single source file");
    }
}

// run it with one command, no javac step:
//   java Hello.java

// Output:
// Hello from a single source file