I'm developing a RCP application that contains a TableViewer. This is my first attempt at a RCP app, so sorry if this is a silly question.
I'm having trouble with the content provider's inputChanged method. The input objects in the table are Strings. Here is the method, as I have so far (Scenario is a class in my app, with a displayData method):
public void inputChanged(Viewer v, Object oldInput, Object newInput) {
if (newInput != null) {
String s = (String)newInput;
Scenario.displayData(s);
}
}
When I run it, I get the following Exception:
java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.lang.String
How did the class name get garbled? I tried printing out the class name, using newInput.getClass().getName(), and still got the garbled version.
The "[L" means it's an array of strings.
Related
I'm a beginner, so I'm sensing I'm making a simple mistake but I haven't been able to figure it out or find reference to a similar error on other forums.
My end goal is to create a graphic that changes colour depending on the time of day. Right now my issue is that I can not get a Date object to return anything for the life of me.
This is all I have put in a file called Main.as, that is called in one of the keyframes:
public class Main extends MovieClip {
var myDate1:Date = new Date();
trace(myDate1);
}
According to the API, if I don't define a specific date it should just take the current date from my system. But instead of doing the trace I keep getting "error 1120: Access of undefined property myDate1".
Why am I getting this error?
I should note I'm trying to make this for mobile so I've been testing the movie using AIR launcher.
Your script is wrong. You are not supposed to write code directly inside the class body. You need to define methods:
public class Main extends MovieClip
{
// Class constructor.
public function Main()
{
super();
// Output the current date.
trace(NOW);
}
// Static class property that always returns the current date.
static public function get NOW():Date
{
return new Date;
}
}
I read many question in this forum but nothing works.
public #interface MyAnnotation {
String value() default "";
Class[] exceptionList;
}
#MyAnnotation(value="hello", exceptionList={TimeOutException.class})
public void method() {}
#Aspect
public class MyAspect {
#Around("#annotation(MyAnnotation)")
public Object handle(ProceedingJoinPoint joinPoint, MyAnnotation myAnnotation) {
System.out.println(myAnnotation.exceptionList); // should print out TimeOutException
}
}
How can I get the value and the exceptionList of the #MyAnnotation while executing the advice?
I'm using Spring 4.0.6, AspectJ 1.7.4
The solution for this is making sure the advice method's parameter name match the parameter name in AspectJ expression. In my case, the advice method should look like this:
#Aspect
public class MyAspect {
#Around("#annotation(myAnnotation)")
public Object handle(ProceedingJoinPoint joinPoint, MyAnnotation myAnnotation) {
System.out.println(myAnnotation.exceptionList); // should print out TimeOutException
}
}
You are already almost there. Probably.
You are using the correct way to retrieve the annotation, so you have the values available.
Your problem - if I interpret the very minimalistic problem description(!) you only provide via the comment in your code snippet(!) correctly - is the (wrong) assumption that sticking an array of the type Class into System.out.println() will print out the names of the Classes it contains. It does not. Instead it prints information about the reference:
[Ljava.lang.Class;#15db9742
If you want the names of the Classes, you will have to iterate over the elements of that array and use .getName(), .getSimpleName() or one of the other name providing methods of Class.
Further information on how to print elements of an array is here:
What's the simplest way to print a Java array?
Granted, this whole answer could be entirely besides the point if the problem is that you are getting null values from the annotation fields. But since you have not provided an adequate problem description ("nothing works" is not a problem description!), we can only guess at what your problem is.
I am using Spring 4 + Jackson 2 and have written a fully functional POST method using #RequestBody on a custom class. This method has no trouble unmarshalling the object.
#ResponseBody
#RequestMapping(value="store", method = RequestMethod.POST)
public ServiceResponse store(#RequestBody CustomClass list) {
...
}
// Request: { code: "A", amount: 200 }
When I attempted to add another method to handle a collection of the same class instead, my POST requests were returning with the following error.
HTTP Status 400: The request sent by the client was syntactically incorrect.
I note that this error typically occurs when the JSON submitted does not match the entity class. However, all I am doing is submitting an array of the same object instead of the object itself, which has already proven to work.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody List<CustomClass> list) {
...
}
// Request: [{ code: "A", amount: 200 }, { code: "B", amount: 400 }]
Am I missing something here?
In Java, type information for generics is erased at runtime, so Spring sees your List<CustomClass> object as List<Object> object, thus it cannot understand how to parse it.
One of ways to solve it, you could capture the type information by creating a wrapper class for your list, like this:
public class CustomClassList extends ArrayList<CustomClass> {
}
Sergey is right that the issue is due to type erasure. Your easiest way out is to bind to an array, so
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody CustomClass[] object) {
...
}
The answer is that Spring 4 doesn't actually get rid of type erasure, contrary to what some other solutions suggest. While experimenting on debugging via manual unmarshalling, I decided to just handle that step myself instead of an implicit cast that I have no control over. I do hope someone comes along and proves me wrong, demonstrating a more intuitive solution though.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody String json) {
try {
List<CustomClass> list = new ObjectMapper().readValue(json, new TypeReference<List<CustomClass>>() { });
...
} catch (Exception e) {
...
}
}
Bonus: Right after I got this working, I bumped into this exception:
IllegalStateException: Already had POJO for id
If anyone gets this, it's because the objects in the list happen to reference some object that another item in the list already references. I could work around this since that object was identical for my entire collection, so I just removed the reference from the JSON side from all but the first object. I then added the missing references back after the JSON was unmarshalled into the List object.
Two-liner for the Java 8 users (the User object reference was the issue in my case):
User user = list.get(0).getUser();
list.stream().filter(c -> c.getUser() == null).forEach(t -> t.setUser(user));
I have some problem with the Google's AutoBean serialization and deserialization.
I have an AutoBean that contains primitive types and Maps as well. I can serialize and deserialize the primitive types without any problem, but when i try to read the deserialized Map, i get NullPointerException.
Have you ever met with a similar problem before? There is a JUnit test that representes my problem. The first two asserts are passes, but the third fails.
public class AutoBeanTest {
#Test
public void test() throws Exception {
MyFactory myFactory = AutoBeanFactorySource.create(MyFactory.class);
Options options = myFactory.options().as();
options.setMyInt(5);
HashMap<Double, Boolean> map = newHashMap();
map.put(8.0, true);
map.put(9.1, false);
options.setMyMap(map);
Options deserialized = AutoBeanCodex.decode(myFactory, Options.class, AutoBeanCodex.encode(AutoBeanUtils.getAutoBean(options)).getPayload()).as();
assertEquals(deserialized.getMyInt(),5);
assertTrue(options.getMyMap().containsKey(8d));
assertTrue(deserialized.getMyMap().containsKey(8d));
}
public interface MyFactory extends AutoBeanFactory {
AutoBean<Options> options();
}
public interface Options {
public int getMyInt();
void setMyInt(int myInt);
Map<Double, Boolean> getMyMap();
void setMyMap(Map<Double, Boolean> myMap);
}
}
I've been playing around with the AutoBean functionality a while ago. I think it is still kind a buggy. I'm quite sure the exceptions is caused by a bug in the AutoBean code, not in your code.
If you run the above sample code in a debugger and check the generated JSON, things look fine. You can even call deserialized.getMyMap().size() and get the correct value, but once you want to access the content errors occur.
There is a workaround, just use Map<String, String> instead of Double or Boolean and it works...
Ackchyually... Autobeans is doing it correctly as in JSON only strings are allowed as keys. But of course the error message should be more helpful.
My App engine/ GWT project is spitting out a nasty little pile of stack trace whenever it attempts to return from my login method. I am using GAE version 1.5.0 and GWT version 2.3.0 .
It's a facebook app, so what I've got is this:
The player navigates to the app page.
They click a button, and are redirected to the OAuth authentication page
They are then redirected back to the app, with the authentication token in the query string
I break the query string apart to get the UID, and then use that as the primary key for my Player entity (RPC to app engine backend)
I retrieve the Player entity instance from the datastore, and turn it into a serializable type to return to the client
Epic fail.
When I spit out the exception in a JSAlert, I get a big nasty pile of stack trace (I already was thoughtful enough to compile using "pretty" instead of "obfuscated").
My login function looks like this:
#Override
public ClientPlayer login(String uid) {
PersistenceManager pm=PMF.get().getPersistenceManager();
log.warning(Player.class.getName());
log.warning(uid);
Key k=KeyFactory.createKey(Player.class.getSimpleName(), uid);
Player p;
List<List<Integer>> stats;
try{
p=pm.getObjectById(Player.class, k);
} catch (JDOObjectNotFoundException e){
p=new Player(uid);
p.setKey(k);
pm.makePersistent(p);
} finally {
pm.close();
}
stats=p.getStats();
return new ClientPlayer(p.getUID(),p.getPerm(), p.getDecks(),stats.get(0), stats.get(1), stats.get(2));
}
Unfortunately, due to NDA, I can't link to the app, but here's the output:
Failure to log in because of:
com.google.gwt.core.client.JavaScriptException: (TypeError): Cannot call method 'nullMethod' of null
arguments: nullMethod,
type: non_object_property_call
stack: TypeError: Cannot call method 'nullMethod' of null
at Object.ClientPlayer_1 (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:993:89)
at Object.ClientPlayer_0 (http://*com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:984:18)
at Array.instantiate_1 [as 0] (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:1031:10)
at $instantiate_0 (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:10660:34)
at $instantiate (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:1948:10)
at $readObject (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:10148:95)
at Object.read_8 [as read] (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:10608:10)
at $onResponseReceived (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:10352:247)
at $fireOnResponseReceived (http://*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:5002:5)
at Object.onReadyStateChange (http:/*.com/com.MES.Tap2/A37A2E2E9A65DB1BAAE2BFA42572F7F8.cache.html:5222:5)
The issue was in the use of the IsSerializable interface, or rather my poor understanding of it.
When you create an IsSerialiazable object, it requires a no-argument constructor. I was passing null values from that constructor to the main constructor, so when methods were called on them, null pointer exceptions occurred. This was dumb of me, but hey, it was a learning experience.
In my particular case, it went a little like this...
public class ClientObject implements IsSerializable {
private Object field1;
private Object field2;
private String field3;
public ClientObject(){
this(null, null);
}
public ClientObject(Object arg1, Object arg2){
field1=arg1;
field2=arg2;
field3=arg1.toString()+arg2.toString();
//Error on above line, though not obviously mentioned in the message
}
}
What should have been done was...
public ClientObject(){
this(new Object(), new Object());
}
Hope this helps someone.