Programming in Java bytecode [closed]

You could try Jasmin!

.class public HelloWorld
.super java/lang/Object

.method public static main([Ljava/lang/String;)V
  .limit stack 3
  .limit locals 1

  getstatic      java/lang/System/out Ljava/io/PrintStream;
  ldc            "Hello World."
  invokevirtual  java/io/PrintStream/println(Ljava/lang/String;)V

  return

.end method

You compile it using:

> java -jar jasmin.jar hello.j

And then you run it like any class:

> java HelloWorld
Hello World.

Update

I see that your question mentions “without using Javac or Java”. Could you clarify how you meant that statement?