Reference to generic type Set E should be parmeterized

I have the following code in a class:
1:Event theEvent = (Event) session.load(Event.class, eventId);
            2:Set<Event> eventSet;
            3:eventSet = user.getFavouriteEvents();
            4:eventSet.add(theEvent);At line 3, I get the following warning message:
Type safety: The expresson of raw type Set is converted to Set<Event>. References to generic type Set<E> should be parameterized.
What does this mean? What do I need to do to get past this warning.
Thanks
Sharma

Found the problem. I forgot to parameterize the Set in the getFavouriteEvents() method.
Thanks
Sharma

Similar Messages

Java5: Can't find a way to get rid of warnings about generic types

Hi all,
i have this method:
    public static void insert(List list, int index, Object obj) {
        list.add(obj);
        int j = list.size() - 1;
        for (; j > index; j--) {
            list.set(j - 1, list.get(j));
        list.set(index, obj);
    }I get 3 warnings. All about:
Type safety: The method add(Object) belongs to the raw type List. References to generic type List<E> should be parameterized
I can't find a way to rewrite this method (Java5), that i get no warnings compiling it and calling it with:
List<AnyClass> list = new ArrayList<AnyClass>();
list.add(new AnyClass());
AnyClass ac = new AnyClass();
insert(list, 0, ac);May be you know another way to insert an element to a List?
Thanks

Never tried it and do not have 5.0 installed to test
it, but what if you define the ArrayList as follows?
List<Object> list = new ArrayList<Object>();
That should get rid of the warnings.

Comparison of references between generics. Missing error/warning?

If you compare two object references belonging to classes not assignable to each-other either way like this:
public class SameClassStringBuffer {
    public boolean same (Class c, StringBuffer sb) {
           return c == sb;
}The sun compiler returns and error saying:
incomparable types: java.lang.Class and java.lang.StringBuffer
           return c == sb;^
... what makes sense.
Now, if you compare two references with generic types potentially not asignable to each other there is no error. The following compiles with no complains:
public class Same<X,Y> {
    public boolean same (X a, Y b) {
           return a == b;
}It it obvious that at runtime that is not an issue cause both are Object type references at that point, yet it is still, in my opinion, an unsafe and bug prone code. Why is there no error or at least a warning message? A case not contemplated by the language steering group? Or am I missing something?
Thanks.

But generics is a (probably the) mejor source of warning in java today. The solution is typically a cast and or adding the annotation @SuppressWarning to silence it.
In this particular case, if there was at least a warning, you would need to cast the references explicitly to something common (Object should always work) and then compare.
x == (Object)yThe point of the warning is to tell the programmer that what he is doing may cause problems; "you can go ahead but double check if it is really what you want".
As side note, a warning would have spare me a couple of hours trying to find out what was going on in a piece of code of mine (not as trivial as the example). I'd rather had the "annoying" warning. In any case I think there is little to wonder about the cause of such warning or error as it would just be consistent to the behaviour with specific types. If people still wonders what it means looking at that comparison between (potentially) different typed references I guess they should learn a bit more Java or OO before anything (No offence for anybody intended).

The type Set is not generic; it cannot be parameterized with arguments K ?

When I use Hashtable or HashMap to get the keySet, it shows the error of "The type Set is not generic; it cannot be parameterized with arguments <K>".
The following is my code:
Hashtable table = new Hashtable();
table.put("A", new Integer(1));
table.put("B", new Integer(2));
Iterator its = table.keySet().iterator(); // <<<<<<<<<<<<<< this line shows the error "The type Set is not generic; it cannot be parameterized with arguments <K>"
How can I solve it? Please help me! I have no idea on it. It works fine in 1.4.
Best regards,
Eric

The original is my codes, please help!
public static List findDlicApp(Date startDate, Date endDate, Connection con) {
          String SQL = getSQL("app.sql");
          String where = getSQL("app.sql.where");
          boolean hasWhere = false;
          if (startDate != null) {
               SQL = SQL + " where d.create_date >= to_date('" + DMSUtil.convertDateToString(startDate) + "', 'yyyy-MM-dd')";
               hasWhere = true;
          if (endDate != null) {
               if (hasWhere) {
                    SQL = SQL + " and to_date(to_char(d.create_date, 'yyyy-mm-dd'), 'yyyy-mm-dd') <= to_date('" + DMSUtil.convertDateToString(endDate) + "', 'yyyy-MM-dd')";
               } else {
                    SQL = SQL + " where to_date(to_char(d.create_date, 'yyyy-mm-dd'), 'yyyy-mm-dd') <= to_date('" + DMSUtil.convertDateToString(endDate) + "', 'yyyy-MM-dd')";
               hasWhere = true;
          if (hasWhere) {
               SQL = SQL + " and " + where;
          } else {
               SQL = SQL + " where " + where;
          SQL = SQL + " " + getSQL("app.sql.order");
          //System.out.println(SQL);
          //Connection con = getParaDMConnection("findDlicApp");
          HashMap<String, DlicApp> dlicDocs = new HashMap<String, DlicApp>();
          List result = new ArrayList();
          try {
               Statement stmt = con.createStatement();
               ResultSet rs = stmt.executeQuery(SQL);
               long lastDocID = 0;
               boolean hasStartDate = false;
               while(rs.next()) {
                    long docID = rs.getLong("docID");
                    String docName = rs.getString("docName");
                    String refNo = rs.getString("refNo");
                    java.util.Date createDate = rs.getDate("createDate");
                    String creator = rs.getString("creator");
                    String profileType = rs.getString("profileType");
                    String assunto = rs.getString("assunto");
                    String fromEntity = rs.getString("fromEntity");
                    String location = getLocation(docID, con);
                    long fieldID = rs.getLong("fieldID");
                    String fieldValue = rs.getString("fValue");
                    DlicApp doc = null;
                    if (dlicDocs.containsKey(String.valueOf(docID))) {
                         doc = (DlicApp)dlicDocs.get(String.valueOf(docID));
                    } else {
                         doc = new DlicApp();
                    doc.setId(docID);
                    doc.setDocName(docName);
                    doc.setReferenceNo(refNo);
                    doc.setCreateDate(createDate);
                    doc.setCreator(creator);
                    doc.setProfileType(profileType);
                    doc.setAssunto(assunto);
                    doc.setFrom(fromEntity);
                    //if (doc.getStartDate() == null) {
                    //     doc.setStartDate(createDate);
                    doc.setLocation(location);
                    if (fieldValue != null) {
                         if (fieldID == 1114) {
                              doc.setChineseName(fieldValue);
                         if (fieldID == 1115) {
                              doc.setPortugueseName(fieldValue);
                         if (fieldID == 1116) {
                              doc.setApplicationCategory(fieldValue);
                         if (fieldID == 1118) {
                              doc.setStatus(fieldValue);
                         if (fieldID == 1119) {
                              Date d = DMSUtil.parseDate(fieldValue, "yyyy-MM-dd");
                              doc.setStartDate(d);
                              hasStartDate = true;
                         if (fieldID == 1120) {
                              Date d = DMSUtil.parseDate(fieldValue, "yyyy-MM-dd");
                              if (!StringUtils.isEmpty(fieldValue)) {
                                   //System.out.println(docName + ":" + fieldValue + ">>>>>>>>>findDlicApp>>>>>>>>>>>>>>>>>>APP END DATE: " + d);
                                   doc.setEndDate(d);
                    if (docID != lastDocID) {
                         doc.setRelatedDocs(findRelatedDoc(docID, con));
                         lastDocID = docID;
                    dlicDocs.put(String.valueOf(docID), doc);
               stmt.close();
               rs.close();
               Iterator<String> its = dlicDocs.keySet().iterator();
               while(its.hasNext()) {
                    String id = (String)its.next();
                    DlicApp a = (DlicApp)dlicDocs.get(id);
                    a.setRelatedDocs(findRelatedDoc(a.getId(), con));
                    dlicDocs.put(id, a);
               result.addAll(dlicDocs.values());
               // take out start date is not in the given period
               int n = 0;
               while(true) {
                    if (n < result.size()) {
                         DlicApp a = (DlicApp)result.get(n);
                         Date sd = a.getStartDate();
                         if (!isWithin(sd, startDate, endDate)) {
                              result.remove(n);
                         } else {
                              n++;
                    } else {
                         break;
          } catch(Exception e) {
               e.printStackTrace();
          if (result.size() > 0) {
               Collections.sort(result, new DmsDocComparator());
          return result;
     }Edited by: EJP on 13/01/2011 14:41: added code tags for you. Please use them next time.

Passing a reference to a type definition to a SubVI

I have created a type definition that I would like to use across my application. This particular type definition is also the front panel control to my top level VI. I wanted to pass a reference to this control to my SubVi's so that they could dereference as needed and in very rare cases update the values on the front panel. However, as I built the application I noticed that I was breaking the control reference as I updated the type definition. This implies that they type of the reference changes as I change the type definition.
How do I go about building the reference I need or is there some other way to do this that works just as well. Even if I can't make a reference to the control that is tied to the type definition, I'm willing to pass in a variant who can house the reference as long as I can build the data type (the reference) inside my SubVis.
Solved!
Go to Solution.

Okay, so I tried all three approaches in a SubVI, here's what happened.
My approach was simply to create a Type Def control, right-click and create a Reference. Then create a control from that reference by right-clicking the output of the reference and selecting the Create Control option. I then pasted this 'cluster' reference into my SubVi, made it an input and then wired up the reference in the parent to the control in the SubVi.
Result: This breaks when you update the Type Definition.
Next, Ben's approach (or my best effort at doing what he suggested). I created a control from reference to the type def. I cut it from the parent VI and pasted it into a new type def. I then put the type def in the SubVI and set it as an input.
Result: This breaks when you update the Type Definition (but it actually takes a bit longer for the error to propogate).
Finally, Christian's solution (or my best effort). I took the type def reference and put it through a To More Generic Class guy, casting it to a Control Refnum. I put a Control Refnum on the front panel of my SubVI and wired it to a To More Specific Class guy. I created a control of the type def in the subvi, hid it, and created a reference. I wired the reference to the more specific guy and verified I was getting the right data.
Result: It works!
It's possible I just didn't understand how to make the reference type def you were referring to Ben. I would prefer a method with less verbage. I pass this refnum into a class which holds it. Since I can't replicate the type exactly prior to run time (i.e. create a control that is exactly a reference to the type definition of my front panel), I have to save the reference as a Control Refnum and cast it every time I need it (i.e. create a control from the typedef, create a reference frome the type def, etc). More verbage than optimal, but still good!
Thanks for the help.

[ANN] Java IDE with generic type support

Hello all!
We are proud to announce that we have just released version 5.0 of our Java IDE CodeGuide.
CodeGuide 5.0 offers full support for generic types as defined in JSR 14. Features are:
- Fast incremental on-the-fly compilation
- On-the-fly error checking of the whole project
- Code completion
- Usage search
- Refactoring (like Renaming, Class moving, etc.)
- and more...
A 30-day trial can be downloaded from our web page at
http://www.omnicore.com
Any feedback regarding JSR 14 support is much appreciated.
Best regards,
Dennis Strein
Omnicore Software

I wrote a class MultiMap<K, V> extends Map<K, Set<V>>
    // Various constructors, methods, fields.
    public Set<V> get(K key)
        // Implementation
} It compiles fine with the Sun reference compiler, but a friend tells me that CodeGuide 5.0 build 504 complains "There already is another method with the same erasure." It could be that CodeGuide is correct and Sun wrong, because I can see that there might be issues with overriding the get(Object) method with a get(K), but I thought I'd mention it.

How to create an array with Generic type?

Hi,
I need to create a typed array T[] from an object array Object[]. This is due to legacy code integration with older collections.
The method signature is simple:public static <T> T[] toTypedArray(Object[] objects)I tried using multiple implementations and go over them in the debugger. None of them create a typed collection as far as I can tell. The type is always Object[].
A simple implementation is just to cast the array and return, however this is not so safe.
What is interesting is that if I create ArrayList<String>, the debugger shows the type of the array in the list as String[].
If I create ArrayList<T>, the class contains Object[] and not T[].
I also triedT[] array = (T[]) Array.newInstance(T[].class.getComponentType(), objects.length);And a few other combinations. All work at runtime, create multiple compilation warnings, and none actually creates T[] array at runtime.
Maybe I am missing something, but Array.newInstace(...) is supposed to create a typed array, and I cannot see any clean way to pass Class<T> into it.T[].class.getComponentType()Returns something based on object and not on T, and T.class is not possible.
So is there anything really wrong here, or should I simply cast the array and live with the warnings?
Any help appreciated!

Ok. May be you could keep information about generic type in the your class:
public class Util {
    public static <T> T[] toTypedArray(Class<T> cls, Object[] objects){
        int size = objects.length;
        T[] t = (T[]) java.lang.reflect.Array.newInstance(cls, size);
        System.arraycopy(objects, 0, t, 0, size);
        return t;
public class Sample<T> {
    Class<T> cls;
    T[] array;
    public Sample(Class<T> cls) {
        this.cls = cls;
    public void setArray(Object[] objects){
        array = Util.toTypedArray(cls, objects);
    public T[] getArray(){
        return array;
    public static void main(String[] args) {
        Object[] objects = new Object[] { new LinkedList(), new ArrayList()};
        Sample<List> myClass = new Sample<List>(List.class);
        myClass.setArray(objects);
        for(List elem: myClass.getArray()){
            System.out.println(elem.getClass().getName());
}

Import from database an internal table with generic Type : Web Dynpro ABAP

Hi everyone,
i have a requirement in which i'm asked to transfer data flow between two frameworks, from WD Component to another. The problem is that i have to transfer internal tables with generic types. i used the import/ export from database approache but in that way i get an error message saying "Object references and data references not yet supported".
Here is my code to extract a generic internal table from memory.
    DATA l_table_f4 TYPE TABLE OF REF TO data.
FIELD-SYMBOLS: <l_table_f4> TYPE STANDARD TABLE.
DATA lo_componentcontroller TYPE REF TO ig_componentcontroller .
DATA: ls_indx TYPE indx.
lo_componentcontroller =   wd_this->get_componentcontroller_ctr( ).
lo_componentcontroller->fire_vh_search_action_evt( ).
ASSIGN l_table_f4 TO <l_table_f4>.
*-- Import table for Help F4
IMPORT l_table_f4 TO <l_table_f4> FROM DATABASE indx(v1) TO ls_indx ID 'table_help_f4_ID'.
The error message is desplayed when last instruction is executed " IMPORT l_table_f4...".
I saw another post facing the same problem but never solved "Generic Type for import Database".
Please can anyone help ?
Thanks & Kind regards.

hi KIan,
go:
general type
TYPE : BEGIN OF ty_itab,
           field1 TYPE ztab-field1,
           field2 TYPE ztab-field2,
*your own fields here:
           field TYPE i,
           field(30) TYPE c,
           END OF ty_itab.
work area
DATA : gw_itab TYPE ty_itab.
internal table
DATA : gt_itab TYPE TABLE OF ty_itab.
hope this helps
ec

Call to a possibly undefined method getClipboardContents through a reference with static type flashx.textLayout.edit:ISelectionManager.

Hi Guys,
As i am using the nigtly build of TLF 4.0.0.11073.
I want to copy some text from the TLF, by copy operation. I am getting this type of Error.
- Call to a possibly undefined method getClipboardContents through a reference with static type flashx.textLayout.edit:ISelectionManager.
In the previous build, i dont use to get this type of error, but in this nightly builds i am getting this type of error.
Can anyone help me to fix the same or any workaound.
Thanks in advance.
Krishna

This functionality is still available, but it has moved. It's now in a TextClipboard class, in the same flashx.textLayout.edit package. So you should replace calls to getClipboardFormat() with TextClipboard.getContents().
Hope this helps,
- robin

Activity Type set up for cost center

Hi All ,
While creating a task list i m getting a message
Activity type is not set up for cost center in the year 2008
Message no. CR062
How could i set the activity type for cost center? Plz tell the procedure.
regards
sunil
Edited by: sunil gupta on Sep 19, 2008 10:12 AM

Dear Sunil,
Check out this,
1.Create a Cost center using T code - KS01.
2.Create an activity type using T code - KL01.
3.Assign the Rates for an activity type & cost center combination using T code KP26.
4.In the input screen of T code KP26 ,enter version as 0, from period 1 and to period as 12 and the Fiscal
Year as 2008,enter the cost center, activity type click on overview screen (F5)---> enter the per hour Rate
under Fixed price and set value as 2 for distribution key and plan price indicator as 3.
5.After performing this ,while creating the work center ,this combination of activity type & cost center
should be assigned.Then while creating routing/task list this work center can assigned for performing
operations.
Check with this & revert back if you need any further help.
Regards
Mangalraj.S

How To: Use reflection to create instance of generic type?

I would like to be able to use reflection to instantiate an instance of a generic type, but can't seem to avoid getting type safety warnings from the compiler. (I'm using Eclipse 3.1.1) Here is a trivial example: suppose I want to create an instance of a list of strings using reflection.
My first guess was to write the following:
Class cls = Class.forName("java.util.ArrayList<String>");
List<String> myList = cls.newInstance();The call to Class.forName throws a ClassNotFoundException. OK, fine, so I tried this:
Class cls = Class.forName("java.util.ArrayList");
List<String> myList = cls.newInstance();Now the second line generates the warning "Type safety: The expression of type List needs unchecked conversion to conform to List<String>".
If I change the second line to
List<String> myList = (List<String>)cls.newInstance();then I get the compiler warning "Type safety: The cast from Object to List<String> is actually checking against the erased type List".
This is a trivial example that illustrates my problem. What I am trying to do is to persist type-safe lists to an XML file, and then read them back in from XML into type-safe lists. When reading them back in, I don't know the type of the elements in the list until run time, so I need to use reflection to create an instance of a type-safe list.
Is this erasure business prohibiting me from doing this? Or does the reflection API provide a way for me to specify at run time the type of the elements in the list? If so, I don't see it. Is my only recourse to simply ignore the type safety warnings?

Harald,
I appreciate all your help on this topic. I think we are close to putting this thing to rest, but I'd like to run one more thing by you.
I tried something similar to your suggestion:public static <T> List<T> loadFromStorage(Class<T> clazz) {
    List<T> list = new ArrayList<T>();
    for ( ...whatever ...) {
       T obj = clazz.newInstance();
       // code to load from storage ...
       list.add(obj);
    return list;
}And everything is fine except for one small gotcha. The argument to this method is a Class<T>, and what I read from my XML storage is the fully qualified name of my class(es). As you pointed out earlier, the Class.forName("Foo") method will return a Class<?> rather than a Class<Foo>. Therefore, I am still getting a compiler warning when attempting to produce the argument to pass to the loadFromStorage method.
I was able to get around this problem and eliminate the compiler warning, but I'm not sure I like the way I did it. All of my persistent classes extend a common base class. So, I added a static Map to my base class:class Base
   private static Map<String, Class<? extends Base>> classMap = null;
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      Map<String, Class<? extends Base>> map = new TreeMap<String, Class<? extends Base>>();
      classMap = Collections.synchronizedMap(map);
   public static Class<? extends Base> getClass(String name)
      return classMap.get(name);
   protected static void putClass(Class<? extends Base> cls)
      classMap.put(cls.getName(), cls);
}And added a static initializer to each of my persistent classes:class Foo extends Base
   static
      Base.putClass(Foo.class);
}So now my persistence code can replace Class.forName("my.package.Foo") with Base.getClass("my.package.Foo"). Since Foo.class is of type Class<Foo>, this will give me the Class<Foo> I want instead of a Class<?>.
Basically, it works and I have no compiler warnings, but it is unfortunate that I had to come up with my own mechanism to obtain a Class<Foo> object when my starting point was the string "my.package.Foo". I think that the JDK, in order to fully support reflection with generic types, should provide a standard API for doing this. I should not have to invent my own.
Maybe it is there and I'm just not seeing it. Do you know of another way, using reflection, to get from a string "my.package.Foo" to a Class<Foo> object?
Thanks again for your help,
Gary

How to list those employees who do not have a certain pay rate type set up

Hi,
I'm trying to create a report that lists all employees who DO NOT have a certain pay rate role type set up. An employee can have multiple pay rate roles - for example: chargeable miles, non-chargeable miles, subsistence, etc.
I want to identify all those employees who do not have, say, subsistence yet set up.
I joined the employee table to the employee rates table. The employee_role_id=20 is the particular rate role value that I am interested in. I want to only list those employees who do not have rate of role type 20 set up. That way I can go and set one up for these employees. At present, I am using selection criteria where employee_role_id=20. This brings back only those employees that have an employee_role_id of 20 setup. I would like to do the inverse but setting <>20 only screens out those roles with value 20 and displays all of the rest of the pay role values for each employee.
Any help is appreciated.
thx!
Mark

if you are not sure about the linking i suggest to just show all roles associated to all the employees,
group by employee
create true/false formula for the role_ids where ONLY your 20 role is TRUE per employee
then exclude all false - that should give you only the employees that are missing that particular role.

Rules for casting generics type

I know that there is a section in jsr14 spec about rules of casting generic types, but it seems outdated with
JLS3.
It is obvious that e.g. Class<String> cannot be casted to Class<Integer>.
However in
<T,V> void foo (Class<T> ct) {
Class<V> cv = (Class<V>)ct;
The cast is permitted by the compiler though of course marked as unchecked (The cast should be rejected according to jsr14 spec since none of the types is a subtype of the other).
So the question is: what are the rules, compiler uses to check casts?

1. There is an (unsafe) explicit cast from l1 to l2.
2. There is an implicit cast in the last line, because
l2 is a List<String>, the line is compiled to the
equivalent of
System.out.println(" result:" + (String) l2.get(0));
// ClassCastException: java.lang.String

What types of logs should be kept on activities relating to DBA?

What types of logs should be kept on activities relating to database administrator? How does the operating system assist in maintaining log? What alternatives are available to the IS-Auditor if the operating system does not maintain log?

As has been pointed out in your duplicate thread, these are rather vague and generic questions, so there are no clearly right answers...
What types of logs should be kept on activities
relating to database administrator? That's a business decision, not a technical decision... It depends on government regulations, the type of data in the system, the types of threats that the organization is most concerned with, the performance overhead that is acceptable, etc.
How does the
operating system assist in maintaining log? This is very vague. I don't know how to answer it-- from a database standpoint, the operating system is just holding a file that the DBA (hopefully) cannot update.
What
alternatives are available to the IS-Auditor if the
operating system does not maintain log?Perhaps you're thinking about Audit Vault here?
I need this answer please..! anyone can help meIs this for a school assignment? Or for something in the real world? In the real world, I would expect a lot more information before making any sort of decision on something like this...
Justin

Hunt group type Set up with outside ext numbers ie Cell phones

Using CUCM 9.1
Is there a quick and easy way to create a hunt group type set up using outside (cell phone numbers)?
The scenario will be one (person who will be ON Call) using an internal DID that is forwarded to to a cell phone of the oncall person that particular week. If no answer it would forward to the next line group of 4 members and also try their cell phones. After this it would simply repeat the entire process. So far it looks like a solution may be possible with single line reach perhaps?
Any insight would be grealy appreciated.
Dave

Hello,
I set up something like this on CUCM 8.0 a couple of years ago.
I used the Mobile Connect feature as you suggest and it worked ok after some playing about with the timers.
The main problem was that there was no way for the remote users to log out of the hunt group. They could disable Mobile Connect using the IVR but the calls would still ring on their deskphones - if you log out of the phones (i.e. Extension Mobility) before leaving the office this problem should not occur.
The other issue was how long calls took to connect especially if a couple of people in the group did not answer. We actually recorded a message asking callers to be patient that was played when the call was first received (we were using UCCX to do the IVR and call transfer).
Hope this is of use.

Reference to generic type Set E should be parmeterized

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