throw new Object()

TestExample.java

package ru.izebit;

import org.apache.bcel.Const;
import org.apache.bcel.generic.*;

import java.io.FileOutputStream;

/**
 * @author <a href="izebit@gmail.com">Artem Konovalov</a> <br/>
 * Date: 27/04/2018/.
 */
public class TestExample {
    public static void main(String[] argv) throws Exception {
        generator();
    }

    private static void generator() throws Exception {
        String className = "ru.izebit.Test";
        ClassGen classGenerator = new ClassGen(className, "java.lang.Object", "Test", Const.ACC_PUBLIC, new String[0]);
        InstructionFactory instructionFactory = new InstructionFactory(classGenerator);

        // test();
        // return;
        InstructionList instructionListOfMainMethod = new InstructionList();
        InstructionHandle invokeHandler = instructionListOfMainMethod.append(
                instructionFactory.createInvoke(className, "test",
                        Type.VOID, Type.NO_ARGS, Const.INVOKESTATIC));
        instructionListOfMainMethod.append(InstructionFactory.createReturn(Type.VOID));


        // System.out.println("An exception has been caught");
        InstructionHandle catchBlock = instructionListOfMainMethod.append(
                instructionFactory.createFieldAccess("java.lang.System", "out",
                        new ObjectType("java.io.PrintStream"), Const.GETSTATIC));
        instructionListOfMainMethod.append(InstructionConst.DUP);
        instructionListOfMainMethod.append(new PUSH(classGenerator.getConstantPool(), "An exception has been caught"));
        instructionListOfMainMethod.append(
                instructionFactory.createInvoke("java.io.PrintStream", "println",
                        Type.VOID, new Type[]{Type.STRING}, Const.INVOKEVIRTUAL));
        instructionListOfMainMethod.append(InstructionFactory.createReturn(Type.VOID));

        // public static void main(String[]args)
        MethodGen mainMethodGenerator = new MethodGen(Const.ACC_PUBLIC | Const.ACC_STATIC,
                Type.VOID, new Type[]{new ArrayType(Type.STRING, 1)}, new String[]{"args"},
                "main", className,
                instructionListOfMainMethod, classGenerator.getConstantPool());
        // catch(Object e)
        mainMethodGenerator.addExceptionHandler(invokeHandler, invokeHandler.getNext(), catchBlock, ObjectType.getInstance("java/lang/Object"));
        classGenerator.addMethod(mainMethodGenerator.getMethod());

        // throw new Object()
        InstructionList instructionListOfTestMethod = new InstructionList();
        instructionListOfTestMethod.append(instructionFactory.createNew("java/lang/Object"));
        instructionListOfTestMethod.append(InstructionConst.DUP);
        instructionListOfTestMethod.append(
                instructionFactory.createInvoke("java/lang/Object", "<init>",
                        Type.VOID, Type.NO_ARGS, Const.INVOKESPECIAL));
        instructionListOfTestMethod.append(InstructionConst.ATHROW);
        instructionListOfTestMethod.append(InstructionFactory.createReturn(Type.VOID));

        // public static void test() throws Object
        MethodGen testMethodGenerator = new MethodGen(Const.ACC_PUBLIC | Const.ACC_STATIC,
                Type.VOID, Type.NO_ARGS, new String[0],
                "test", className,
                instructionListOfTestMethod, classGenerator.getConstantPool());
        testMethodGenerator.addException("java/lang/Object");
        testMethodGenerator.stripAttributes(true);
        testMethodGenerator.setMaxStack();
        testMethodGenerator.setMaxLocals();
        classGenerator.addMethod(testMethodGenerator.getMethod());

        String outputPath = TestExample.class.getProtectionDomain().getCodeSource().getLocation().getPath() + "ru/izebit/Test.class";
        try (FileOutputStream fos = new FileOutputStream(outputPath)) {
            classGenerator.getJavaClass().dump(fos);
        }
    }
}