import org.apache.bcel.*; import org.apache.bcel.classfile.*; import org.apache.bcel.generic.*; public class BCELExample { public static void main(String[] args) { JavaClass jclass = Repository.lookupClass("com.example.MyClass"); ConstantPoolGen cpgen = new ConstantPoolGen(jclass.getConstantPool()); Method[] methods = jclass.getMethods(); for (Method method : methods) { InstructionList ilist = new InstructionList(method.getCode().getCode()); InstructionFactory factory = new InstructionFactory(cpgen); ilist.dispose(); ilist.append(factory.createPrintln("Hello, BCEL!")); method.getCode().setCode(ilist.getByteCode()); System.out.println(method.getCode().toString()); } jclass.dump("modified_class.class"); } }