public static void main(String[] args) {
ArrayList<Modifier> modifiers = new ArrayList<Modifier>();
modifiers.add(Modifier.ACC_PUBLIC);
// ================================================================================
// Create an empty class file
// ================================================================================
ClassFile cf =
new ClassFile(
49, // Java 1.5 or later
new JvmType.Clazz("", "HelloWorld"), // class is HelloWorld
JvmTypes.JAVA_LANG_OBJECT, // superclass is Object
Collections.EMPTY_LIST, // implements no interfaces
modifiers); // which is public
// ================================================================================
// Create a static void main(String[]) method
// ================================================================================
modifiers = new ArrayList<Modifier>(modifiers);
modifiers.add(Modifier.ACC_STATIC);
ClassFile.Method method =
new ClassFile.Method(
"main", // main method
new JvmType.Function( // is function
JvmTypes.T_VOID, // from void
new JvmType.Array(JvmTypes.JAVA_LANG_STRING) // to array of String
),
modifiers // which is static public
);
cf.methods().add(method);
// ================================================================================
// Add bytecodes for printing hello world to method
// ================================================================================
ArrayList<Bytecode> bytecodes = new ArrayList<Bytecode>();
bytecodes.add(
new Bytecode.GetField(
JAVA_LANG_SYSTEM, "out", JAVA_IO_PRINTSTREAM, Bytecode.FieldMode.STATIC));
bytecodes.add(new Bytecode.LoadConst("Hello World"));
bytecodes.add(
new Bytecode.Invoke(
JAVA_IO_PRINTSTREAM,
"println",
new JvmType.Function(JvmTypes.T_VOID, JvmTypes.JAVA_LANG_STRING),
Bytecode.InvokeMode.VIRTUAL));
bytecodes.add(new Bytecode.Return(null));
method.attributes().add(new Code(bytecodes, Collections.EMPTY_LIST, method));
// ================================================================================
// Finally, write the class file to disk
// ================================================================================
try {
FileOutputStream fos = new FileOutputStream("HelloWorld.class");
ClassFileWriter cfw = new ClassFileWriter(fos);
cfw.write(cf);
} catch (IOException e) {
System.out.println("I/O error --- " + e.getMessage());
}
}
