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Unable to serialize instance variable of a non-serializable superclass from the serializable subclass

New to this topic and right now I'm stuck at a brick wall. I have 2 classes, parent class: Controller.java and subclass: GreenhouseControls.java. I need to serialize a GreenhouseControls object but also an instance variable (eventList) from its superclass Controller.java.
My serialization happens when an inner class of GreenhouseControls.java throws a custom ControllerException, which is caught in the main method. Before terminating the program, the GreenhouseControls object should be saved (including the field from its superclass).
Why is a NotSerializableException thrown by the inner class WindowMalfunction of GreenhouseControls? Anyone have any ideas, as I am seriously stuck?
What I tried is the following:
Implement serializable on Controller.java. This is because if the superclass is serializable, then subclass is automatically serializable, however this throws java.io.NotSerializableException: GreenhouseControls$WindowMalfunction, (WindowMalfunction is the inner class that throws the initial exception to begin the serialization processs).
Implement serializable on GreenhouseControls.java and implement custom serialization by overriding writeObject() and readObject() to save the field from the superclass. This approach yet again throws the same exception as the approach 1.
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(super.eventList);
}
private void readObject(ObjectInputStream in) throws IOException,
ClassNotFoundException {
in.defaultReadObject();
Object obj = in.readObject();
List<Event> x = cast(obj);
super.eventList = x;
}
Controller.java
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.*;
public class Controller {
// THIS IS THE VARIABLE I NEED TO SAVE
protected List<Event> eventList = new ArrayList<Event>();
public void addEvent(Event c) {
eventList.add(c);
}
public void run() throws ControllerException {
while (eventList.size() > 0)
// Make a copy so you're not modifying the list
// while you're selecting the elements in it:
for (Event e : new ArrayList<Event>(eventList))
if (e.ready()) {
System.out.println(e);
e.action();
eventList.remove(e);
}
}
public static void shutDown() { }
}
GreenhouseControls.java class (note I have removed the inner classes and other code from it and only left related info)
public class GreenhouseControls extends Controller implements Serializable {
private int errorcode = 0;
public class WindowMalfunction extends Event {
public WindowMalfunction(long delayTime) {
super(delayTime);
}
public void action() throws ControllerException {
windowok = false;
throw new ControllerException("Window malfunction");
}
public String toString() {
return "Window malfunction";
}
}
public class PowerOut extends Event {
public PowerOut(long delayTime) {
super(delayTime);
}
public void action() throws ControllerException {
poweron = false;
throw new ControllerException("Power out");
}
public String toString() {
return "Power out";
}
}
// Various other inner classes that extend event exist
public static void serializeObject(GreenhouseControls gc) {
FileOutputStream fileOut;
ObjectOutputStream out;
try {
fileOut = new FileOutputStream("dump.out");
out = new ObjectOutputStream(fileOut);
out.writeObject(gc);
System.out.println("WERRROR code: " + gc.getError());
out.close();
fileOut.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(super.eventList);
}
private void readObject(ObjectInputStream in) throws IOException,
ClassNotFoundException {
in.defaultReadObject();
Object obj = in.readObject();
List<Event> x = cast(obj);
super.eventList = x;
}
#SuppressWarnings("unchecked")
public static <T extends List<?>> T cast(Object obj) {
return (T) obj;
}
public int getError() {
return errorcode;
}
public Fixable getFixable(int errorcode) {
switch (errorcode) {
case 1:
return new FixWindow();
case 2:
return new PowerOn();
default:
return null;
}
}
public static void main(String[] args) {
GreenhouseControls gc = null;
try {
String option = args[0];
String filename = args[1];
if (!(option.equals("-f")) && !(option.equals("-d"))) {
System.out.println("Invalid option");
printUsage();
}
// gc = new GreenhouseControls();
if (option.equals("-f")) {
gc = new GreenhouseControls();
gc.addEvent(gc.new Restart(0, filename));
}
gc.run();
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("Invalid number of parameters");
printUsage();
} catch (ControllerException e) {
String errormsg;
if (e.getMessage().equals("Window malfunction")) {
gc.errorcode = 1;
errormsg = "Window malfunction event occurred Error code: " + gc.errorcode;
} else {
gc.errorcode = 2;
errormsg = "Power out event occurred Error code: " + gc.errorcode;
}
logError(errormsg);
serializeObject(gc);
gc.displayEventList();
shutDown();
}
}
}
Event.java
public abstract class Event {
private long eventTime;
protected final long delayTime;
public Event(long delayTime) {
this.delayTime = delayTime;
start();
}
public void start() { // Allows restarting
eventTime = System.currentTimeMillis() + delayTime;
}
public boolean ready() {
return System.currentTimeMillis() >= eventTime;
}
public abstract void action() throws ControllerException;

Event has to be Serializable too.
Change
public abstract class Event {
to
public abstract class Event implements Serializable {

AspectJ - Use reflection to instanciate object of not public class

I am trying to instanciate an object of a non public class in AspectJ.
I have this class:
package ca1.business;
public class Bill {
int id;
String idOperator;
String idClient;
Bill(int id, String idOperator, String idClient) { /* (...) */ }
public String toString() { /* (...) */ }
public boolean equals(Object o) { /* (...) */ }
public int getId() { /* (...) */ }
public String getOperator() { /* (...) */ }
public String getClient() { /* (...) */ }
}
In the aspects class I wanted to be able to do:
Bill b = new Bill(currInvoice, idOperator, idClient);
The problem is that I get an error:
The constructor Bill(int, String, String) is not visible
So I investigated and tried to use reflection like it's explained in this post.
try {
Constructor<Bill> cons = Bill.class.getDeclaredConstructor(null);
cons.setAccessible(true);
Bill invoice = cons.newInstance(null);
invoice.id = 1;
invoice.idOperator = "foo";
invoice.idClient = "bar";
// etc...
} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
But I get an error in the lines:
invoice.id = 1;
invoice.idOperator = "foo";
invoice.idClient = "bar";
The error is:
The field Bill.X is not visible.
Does anyone know if there is any workaround?

Why use reflection?
Let us assume the Bill class looks like this:
package ca1.business;
public class Bill {
int id;
String idOperator;
String idClient;
Bill(int id, String idOperator, String idClient) {
this.id = id;
this.idOperator = idOperator;
this.idClient = idClient;
}
#Override
public String toString() {
return "Bill [id=" + id + ", idOperator=" + idOperator + ", idClient=" + idClient + "]";
}
public static Bill instance;
public static void main(String[] args) {
System.out.println(instance);
}
}
We want our aspect to populate the static member before main is executed (silly example, just for demo):
Option A: privileged aspect
package de.scrum_master.aspect;
import ca1.business.Bill;
public privileged aspect MyAspect {
before() : execution(public static void main(String[])) {
Bill.instance = new Bill(11, "operator", "client");
}
}
Option B: put aspect into package ca1.business
The constructor is package-private, i.e. other classes in the same package can access it.
package ca1.business;
public aspect MyAspect {
before() : execution(public static void main(String[])) {
Bill.instance = new Bill(11, "operator", "client");
}
}
Option C: put factory class into protected package as a helper
package ca1.business;
public class BillFactory {
public static Bill create(int id, String idOperator, String idClient) {
return new Bill(id, idOperator, idClient);
}
}
package de.scrum_master.aspect;
import ca1.business.Bill;
import ca1.business.BillFactory;;
public aspect MyAspect {
before() : execution(public static void main(String[])) {
Bill.instance = BillFactory.create(11, "operator", "client");
}
}
Console log for each option A, B, C
Bill [id=11, idOperator=operator, idClient=client]

organizing unittests in java/junit for testing classes with common api

I am implementing some elementary sorting algorithms (for the purpose of learning) ,and want to write unittests for them .All the sorting programs have the following common api
...
public static void sort(Comparable[] a);
...
public static boolean isSorted(Comparable[] a);
...
public static boolean isSorted(Comparable[] a),int from ,int to;
...
So,I wrote the following tests for testing the isSorted() method in SelectionSort
public class SelectionSortTests {
String[] a ;
#After
public void tearDown() throws Exception {
a = null;
}
#Test
public void arraySortedSingleElement(){
a = new String[]{"A"};
Assert.assertTrue(SelectionSort.isSorted(a));
}
#Test
public void arraySortedDistinctElements(){
a = new String[]{"A","B","C","D"};
Assert.assertTrue(SelectionSort.isSorted(a));
}
#Test
public void arrayNotSorted(){
a = new String[]{"A","B","C","B"};
Assert.assertFalse(SelectionSort.isSorted(a));
}
...
}
Now I feel that if I were to write tests for say InsertionSort,ShellSort etc ,they would look the same..Only the name of the class under test will change..
So,how should I organize the tests? Is a suite the answer or can I do better using reflection - may be write a driver program to which I can add a list of names of classes to be tested, and the driver invokes runs the common unit tests by passing the classname to it..
I realize this is a common situation..would like to know how this can be handled without spittle or cellotape
UPDATE:
thanks #BevinQ and #Matthew Farwell ,I tried to solve this using Parameterized unit tests.
Used reflection to call the static method ..
Seems to work :) though I think it can still be refactored to avoid duplicate code
#RunWith(Parameterized.class)
public class ParameterizedSortTests {
private Class classToTest;
private Method methodToTest;
public ParameterizedSortTests(String packageName,String classToTest) {
super();
try {
this.classToTest = Class.forName(packageName+"."+classToTest);
} catch (ClassNotFoundException e) {
System.out.println("failed to get class!!");
e.printStackTrace();
}
}
//method return collection of class names to be tested
#Parameterized.Parameters
public static List<Object[]> classesToTest(){
return Arrays.asList(new Object[][]{
{"elemsorts","SelectionSort"} ,
{"elemsorts","InsertionSort"}
});
}
public void setMethod(String method,Class...args){
try {
this.methodToTest = this.classToTest.getMethod(method, args);
} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
#Test
public void arrayIsSorted(){
setMethod("isSorted",Comparable[].class);
String[] a = new String[]{"A","B","C","D"};
Boolean arraySorted = null;
try {
arraySorted = (Boolean)this.methodToTest.invoke(null, new Object[]{a});
System.out.println(this.methodToTest+"returned :"+arraySorted);
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
Assert.assertTrue(arraySorted);
}
#Test
public void arrayIsNotSorted(){
setMethod("isSorted",Comparable[].class);
String[] a = new String[]{"A","B","C","B"};
Boolean arraySorted = null;
try {
arraySorted = (Boolean)this.methodToTest.invoke(null, new Object[]{a});
System.out.println(this.methodToTest+"returned :"+arraySorted);
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//System.out.println("arraySorted="+arraySorted);
Assert.assertFalse(arraySorted);
}
}

for interface
public abstract class AbstractSortTests {
String[] a ;
#After
public void tearDown() throws Exception {
a = null;
}
protected abstract Sorter getSorter();
#Test
public void arraySortedSingleElement(){
a = new String[]{"A"};
Assert.assertTrue(getSorter().isSorted(a));
}
#Test
public void arraySortedDistinctElements(){
a = new String[]{"A","B","C","D"};
Assert.assertTrue(getSorter.isSorted(a));
}
...
}
public class SelectionSortTests extends AbstractSortTests {
protected Sorter getSorter(){
return SelectionSort.getInstance();
}
}
public class QuickSortTests extends AbstractSortTests {
protected Sorter getSorter(){
return QuickSort.getInstance();
}
}
using reflection it is a bit messier but still do-able. I have not tested this code so might have
a couple of bugs, but have used this method in the past. Using interfaces would be the preferred method in 99% of cases.
public abstract class AbstractSortTests {
String[] a ;
#After
public void tearDown() throws Exception {
a = null;
}
protected abstract Sorter getSorter();
#Test
public void arraySortedSingleElement() throws Exception{
a = new String[]{"A"};
Assert.assertTrue(executeMethod(getSorterClass(), "isSorted", a);
}
#Test
public void arraySortedDistinctElements() throws Exception{
a = new String[]{"A","B","C","D"};
Assert.assertTrue(executeMethod(getSorterClass(), "isSorted", a);
}
private void executeMethod(Class<?> sortClass, String methodName, String[] values) throws Exception{
return sortClass.getDeclaredMethod(methodName, new Class[]{String[].class}).invoke(null, new Object[]{values});
}
...
}
public class SelectionSortTests extends AbstractSortTests {
protected Class<?> getSorterClass(){
return SelectionSort.class;
}
}

As #BevynQ says, you'll make life a lot easier for yourself if you make your methods non-static, and you implement an interface (called Sorter below). The you can easily use Parameterized. This is a very quick example of how to use it, (untested, uncompiled)
#RunWith(Parameterized.class)
public class SorterTest {
#Parameters
public static Iterable<Object[]> data() {
return Arrays.asList(new Object[][] {
{ new SelectionSort() },
{ new BubbleSort() }
});
}
private final Sorter sorter
public SorterTest(Sorter sorter) {
this.sorter = sorter;
}
#Test
public void arraySortedSingleElement(){
String[] a = new String[]{"A"};
Assert.assertTrue(sorter.isSorted(a));
}
#Test
public void arraySortedDistinctElements(){
String[] a = new String[]{"A","B","C","D"};
Assert.assertTrue(sorter.isSorted(a));
}
#Test
public void arrayNotSorted(){
String[] a = new String[]{"A","B","C","B"};
Assert.assertFalse(sorter.isSorted(a));
}
}

why not something like this?
#Test
public void arraySortedDistinctElements(){
a = new String[]{"A","B","C","D"};
Assert.assertTrue(SelectionSort.isSorted(a));
Assert.assertTrue(InsertionSort.isSorted(a));
Assert.assertTrue(QuickSort.isSorted(a));
}
I don't think you have more than 10 different sortings to test. so it should be good.
otherway, you can declare all Sorting classes in Array and load using Class properties.

Throw my own exceptions?

I have defined my own expection class:
public class ProduktException extends Exception {
public ProduktException(String msg){
//null
}
public static void throwProduktNotCreatedException() throws ProduktException {
throw new ProduktException("Cannot be created!");
}
public static void throwProduktNotDeletedException () throws ProduktException {
throw new ProduktException("Cannot be deleted!");
}
}
My Problem is I do not know how to throw them when I try:
try {
...
} catch(ProduktNotDeletedException e) {
e.toString();
}
That does not work... But I want to have these structure! What is wrong?
I appreaciate your answer!!!
UPDATE:
My Problem is, I do not want to create several Exception Klasses I want to have all Exceptions in one class. Is there possibly a solution for that?

If you need to differentiate between different kinds of exceptions, just create 2 different exceptions, maybe something like:
public class ProduktException extends Exception
{
public ProduktException(String msg){
//null
}
}
Then have:
public class ProduktNotDeletedException extends ProduktException
{
....
}
and
public class ProduktNotCreatedException extends ProduktException
{
....
}
Then you can catch one or the other, or both.
try {
...
} catch(ProduktNotDeletedException e1) {
e1.toString();
} catch(ProduktNotCreatedException e2) {
e2.toString();
}
EDIT:
For a single class what I mean is:
public class ProduktException extends Exception {
boolean notDeleted;
boolean notCreated;
public ProduktException(String msg){
super(msg);
}
public boolean isNotDeleted() {
return(notDeleted);
}
public boolean isNotCreated() {
return(notCreated);
}
public static void throwProduktNotCreatedException() throws ProduktException {
ProduktException e = new ProduktException("Cannot be created!");
e.notCreated = true;
throw e;
}
public static void throwProduktNotDeletedException () throws ProduktException {
ProduktException e = new ProduktException("Cannot be deleted!");
e.notDeleted = true;
throw e;
}
}
Then in your try/catch:
try {
...
} catch(ProduktException e) {
e.toString();
if(e.isNotCreated()) {
// do something
}
if(e.isNotDeleted()) {
// do something
}
}

You need to either catch ProduktException, e.g.
try {
...
} catch (ProduktException e) {
e.toString();
}
or declare subtypes, e.g.
public ProduktNotDeletedException extends ProduktException
You'll probably want to pass the message in the constructor up, so add the following in your constructor:
super(msg);

The Syntax given below.
class RangeException extends Exception
{
String msg;
RangeException()
{
msg = new String("Enter a number between 10 and 100");
}
}
public class MyCustomException
{
public static void main (String args [])
{
try
{
int x = 1;
if (x < 10 || x >100) throw new RangeException();
}
catch(RangeException e)
{
System.out.println (e);
}
}
}

What you could do if you don't want to create multiple subclasses of your ProduktException for each different type of exception you need to throw is to include a code in the exception which will let you know what is wrong. Something like this:
public class ProduktException extends Exception {
private Code exceptionCode;
private String message
public ProduktException(Code code, String msg){
this.message = msg;
this.exceptionCode = code;
}
//Getters and setters for exceptionCode and message
}
Code can be an enum so that your application can know that each code corresponds to a specific "problem" (product not created, product not deleted, etc.). You can then throw your exceptions like this
throw new ProduktException(Code.PRODUCT_NOT_CREATED,
"Error while creating product");
And when you catch it you can differentiate based on the code.
catch (ProduktException ex) {
if (ex.getExceptionCode().equals(Code.PRODUCT_NOT_CREATED)) {
...
}
else {
...
}
}

Java SwingWorker passing arguments and returning

I'd like to pass in String s, ArrayList<String> als and return
ArrayList<String> als
Run.java
class Run extends SwingWorker<String, Void>
{
private ArrayList<String> als;
private String s;
public Run(String s, ArrayList<String> als) {
this.s = s;
this.als = als;
}
public String doInBackground()
{
return AnotherClass.doSomething(s, als);
}
public void done()
{
try
{
}
catch (Exception ignore)
{
}
}
}
AnotherClass.java
public class AnotherClass{
public static String doSomething(String ipRange, ArrayList<String> nmapPorts) {
//do some stuff with the strings
try{
ProcessBuilder builder = new ProcessBuilder("someexe", "flag", cmds,
"&cd");
builder.redirectErrorStream(true);
Process pr = builder.start();
//do some stuff with the stream.
return aString;
}catch (IOException e){}
}
}

As you have initialized your class members in constructor you can always use global variables in SwingWorker.
class Run extends SwingWorker<List<String>, Void, Void>
{
private ArrayList<String> als;
private String s;
public Run(String s, ArrayList<String> als) {
this.s = s;
this.als = als;
}
public String doInBackground()
{
//this is right way to do it and you are correct here.
//Following called method must return ArrayList<String>
return AnotherClass.doSomething(s, als);
}
public void done()
{
ArrayList<String> retList = null;
try
{
//When doInBackground finishes done method is called and to get data from doInBackground it uses following method
retList = get();
als = retList;
}
catch (Exception ignore)
{
}
}
}