Request for help with generics-related compiler warnings

[PhilipJohnson]

Greetings, Wicket Wizards,

I am updating a sample Wicket program from 1.3.6 to 1.4.3 and running into
a few generics-related issues.   I am hoping you folks can quickly set me
straight. My code appears to run successfully and passes its JUnit tests,
despite the warnings I would like to remove.  The purpose of the code is
to demonstrate simple use of Forms, Lists, and Tables and associated
testing of these constructs using WicketTester.

First off, although you hopefully will not need to, you can download the
sample code from here:
<http://ics-wicket-examples.googlecode.com/files/wicket-example02-1.0.1106.zip>

Unzip, cd into the directory, and type "ant", It should download Ivy, then
download Wicket, Jetty, SLF4J, and JUnit, and finally compile the system,
generating the following generic-related warnings.   Let me now show you
what they are:

Problem 1:  please take a look at line 39 of TablePage.java:
<http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java>

The problematic line is:
new ListDataProvider(contacts)

and obviously requires a generic argument, but neither of the following
work:
  new ListDataProvider<Contact>(contacts)  // my preferred guess
  new ListDataProvider<List<Contact>>(contacts)

The compiler warning is:
    [javac] TablePage.java:39: warning: [unchecked] unchecked call to
ListDataProvider(java.util.List<T>) as a member of the raw type
org.apache.wicket.markup.repeater.data.ListDataProvider
    [javac]         new ListDataProvider(contacts)) {
    [javac]         ^
    [javac] TablePage.java:39: warning: [unchecked] unchecked conversion
    [javac] found   :
org.apache.wicket.markup.repeater.data.ListDataProvider
    [javac] required:
org.apache.wicket.markup.repeater.data.IDataProvider<java.util.List<edu.hawaii.wicket.TablePage.Contact>>
    [javac]         new ListDataProvider(contacts)) {
    [javac]         ^

Problem 2:  on line 49 of the same file, TablePage.java:
<http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java>

The line is:
Contact contact = (Contact) item.getModelObject();

Since the preceding line provides a parameterized declaration of  item
(Item<List<Contact>> item), I don't understand why I need to cast here.
But the code does not compile if I don't.  Then, I get the following
warning:

    [javac] TablePage.java:49: warning: [unchecked] unchecked cast
    [javac] found   : java.util.List<edu.hawaii.wicket.TablePage.Contact>
    [javac] required: edu.hawaii.wicket.TablePage.Contact
    [javac]         Contact contact = (Contact) item.getModelObject();
    [javac]
                                                 ^

Problem 3:  WicketTester and generics.

I clearly don't understand how to test with WicketTester.  Take a look at
lines 37-39 of TestListPage:
<http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TestListPage.java>

This is a mess, and generates the following warning:
    [javac] TestListPage.java:39: warning: [unchecked] unchecked cast
    [javac] found   : capture#294 of ?
    [javac] required: java.util.List<java.lang.String>
    [javac]     List<String> metaVars = (List<String>)
varsModel.getObject();

I have a feeling that my whole approach to getting values out of the table
for testing is wrong, but I don't know what the correct approach is.

If any of you can give me a hand, the first Mai Tai is on me the next time
you are in Hawaii.

Thanks!
Philip





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[reiern70]

This does not produces any warnings

public class TablePage extends WebPage {

  /** Support serialization. */
  private static final long serialVersionUID = 1L;

  /**
   * Creates a page containing a table of Contacts.
   */
  public TablePage() {

    // Initialize our list of Contact instances.
    // Use ArrayList, not List, since ArrayList is Serializable.
    ArrayList<Contact> contacts = new ArrayList<Contact>();
    contacts.add(new Contact("Joe Smith", "123 Honu St., Kailua, HI
96734"));
    contacts.add(new Contact("Sally Forth", "456 Alapapa St., Honolulu, HI
96813"));

    // Create the dataview to display our list of contact instances.
    // Note that the following commented out line is OK from a type
perspective.
    // ListDataProvider<Contact> test = new
ListDataProvider<Contact>(contacts);

    // But we can't say new ListDataProvider<Contact> in the next line. Why?
    DataView<Contact> dataView = new DataView<Contact>("ContactList",
        new ListDataProvider<Contact>(contacts)) {
      /** For serialization. */
      private static final long serialVersionUID = 1L;

      /**
       * Display each row in the table.
       *
       * @param item A Contact instance to be displayed.
       */
      public void populateItem(Item<Contact> item) {
        Contact contact = (Contact) item.getModelObject();
        item.add(new Label("Name", contact.getName()));
        item.add(new Label("Address", contact.getAddress()));
      }
    };

    // Add the dataview to the TablePage.
    add(dataView);
  }

  /**
   * An inner class implementing a record of data to be displayed as a row
in the table. Package
   * private so that TestTablePage can access it.
   *
   * @author Philip Johnson
   */
  static class Contact implements Serializable {
    /** Support serialization. */
    private static final long serialVersionUID = 2L;
    private String name;
    private String address;

    /**
     * Create a new contact, given a name and an address.
     *
     * @param name The name.
     * @param address The address.
     */
    public Contact(String name, String address) {
      this.name = name;
      this.address = address;
    }

    /**
     * Return the name.
     *
     * @return The name of this contact.
     */
    public String getName() {
      return name;
    }

    /**
     * Return the address of this contact.
     *
     * @return The address.
     */
    public String getAddress() {
      return address;
    }
  }
}

at least on my IDE

Best,

Ernesto

On Sat, Nov 7, 2009 at 9:42 AM, Philip Johnson <johnson@...> wrote:

> Greetings, Wicket Wizards,
>
> I am updating a sample Wicket program from 1.3.6 to 1.4.3 and running into
> a few generics-related issues.   I am hoping you folks can quickly set me
> straight. My code appears to run successfully and passes its JUnit tests,
> despite the warnings I would like to remove.  The purpose of the code is to
> demonstrate simple use of Forms, Lists, and Tables and associated testing of
> these constructs using WicketTester.
>
> First off, although you hopefully will not need to, you can download the
> sample code from here:
> <
> http://ics-wicket-examples.googlecode.com/files/wicket-example02-1.0.1106.zip
> >
>
> Unzip, cd into the directory, and type "ant", It should download Ivy, then
> download Wicket, Jetty, SLF4J, and JUnit, and finally compile the system,
> generating the following generic-related warnings.   Let me now show you
> what they are:
>
> Problem 1:  please take a look at line 39 of TablePage.java:
> <
> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java
> >
>
> The problematic line is:
> new ListDataProvider(contacts)
>
> and obviously requires a generic argument, but neither of the following
> work:
>  new ListDataProvider<Contact>(contacts)  // my preferred guess
>  new ListDataProvider<List<Contact>>(contacts)
>
> The compiler warning is:
>   [javac] TablePage.java:39: warning: [unchecked] unchecked call to
> ListDataProvider(java.util.List<T>) as a member of the raw type
> org.apache.wicket.markup.repeater.data.ListDataProvider
>   [javac]         new ListDataProvider(contacts)) {
>   [javac]         ^
>   [javac] TablePage.java:39: warning: [unchecked] unchecked conversion
>   [javac] found   : org.apache.wicket.markup.repeater.data.ListDataProvider
>   [javac] required:
> org.apache.wicket.markup.repeater.data.IDataProvider<java.util.List<edu.hawaii.wicket.TablePage.Contact>>
>   [javac]         new ListDataProvider(contacts)) {
>   [javac]         ^
>
> Problem 2:  on line 49 of the same file, TablePage.java:
> <
> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java
> >
>
> The line is:
> Contact contact = (Contact) item.getModelObject();
>
> Since the preceding line provides a parameterized declaration of  item
> (Item<List<Contact>> item), I don't understand why I need to cast here. But
> the code does not compile if I don't.  Then, I get the following warning:
>
>   [javac] TablePage.java:49: warning: [unchecked] unchecked cast
>   [javac] found   : java.util.List<edu.hawaii.wicket.TablePage.Contact>
>   [javac] required: edu.hawaii.wicket.TablePage.Contact
>   [javac]         Contact contact = (Contact) item.getModelObject();
>   [javac]
>                                                ^
>
> Problem 3:  WicketTester and generics.
>
> I clearly don't understand how to test with WicketTester.  Take a look at
> lines 37-39 of TestListPage:
> <
> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TestListPage.java
> >
>
> This is a mess, and generates the following warning:
>   [javac] TestListPage.java:39: warning: [unchecked] unchecked cast
>   [javac] found   : capture#294 of ?
>   [javac] required: java.util.List<java.lang.String>
>   [javac]     List<String> metaVars = (List<String>) varsModel.getObject();
>
> I have a feeling that my whole approach to getting values out of the table
> for testing is wrong, but I don't know what the correct approach is.
>
> If any of you can give me a hand, the first Mai Tai is on me the next time
> you are in Hawaii.
>
> Thanks!
> Philip
>
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@...
> For additional commands, e-mail: users-help@...
>
>

[reiern70]

and the casting is no longer needed

DataView<Contact> dataView = new DataView<Contact>("ContactList",
        new ListDataProvider<Contact>(contacts)) {
      /** For serialization. */
      private static final long serialVersionUID = 1L;

      /**
       * Display each row in the table.
       *
       * @param item A Contact instance to be displayed.
       */
      public void populateItem(Item<Contact> item) {
        Contact contact = item.getModelObject();
        item.add(new Label("Name", contact.getName()));
        item.add(new Label("Address", contact.getAddress()));
      }
    };

Regards,

Ernesto

On Sat, Nov 7, 2009 at 10:14 AM, Ernesto Reinaldo Barreiro <
reiern70@...> wrote:

> This does not produces any warnings
>
> public class TablePage extends WebPage {
>
>   /** Support serialization. */
>   private static final long serialVersionUID = 1L;
>
>   /**
>    * Creates a page containing a table of Contacts.
>    */
>   public TablePage() {
>
>     // Initialize our list of Contact instances.
>     // Use ArrayList, not List, since ArrayList is Serializable.
>     ArrayList<Contact> contacts = new ArrayList<Contact>();
>     contacts.add(new Contact("Joe Smith", "123 Honu St., Kailua, HI
> 96734"));
>     contacts.add(new Contact("Sally Forth", "456 Alapapa St., Honolulu, HI
> 96813"));
>
>     // Create the dataview to display our list of contact instances.
>     // Note that the following commented out line is OK from a type
> perspective.
>     // ListDataProvider<Contact> test = new
> ListDataProvider<Contact>(contacts);
>
>     // But we can't say new ListDataProvider<Contact> in the next line.
> Why?
>     DataView<Contact> dataView = new DataView<Contact>("ContactList",
>         new ListDataProvider<Contact>(contacts)) {
>       /** For serialization. */
>       private static final long serialVersionUID = 1L;
>
>       /**
>        * Display each row in the table.
>        *
>        * @param item A Contact instance to be displayed.
>        */
>       public void populateItem(Item<Contact> item) {
>         Contact contact = (Contact) item.getModelObject();
>         item.add(new Label("Name", contact.getName()));
>         item.add(new Label("Address", contact.getAddress()));
>       }
>     };
>
>     // Add the dataview to the TablePage.
>     add(dataView);
>   }
>
>   /**
>    * An inner class implementing a record of data to be displayed as a row
> in the table. Package
>    * private so that TestTablePage can access it.
>    *
>    * @author Philip Johnson
>    */
>   static class Contact implements Serializable {
>     /** Support serialization. */
>     private static final long serialVersionUID = 2L;
>     private String name;
>     private String address;
>
>     /**
>      * Create a new contact, given a name and an address.
>      *
>      * @param name The name.
>      * @param address The address.
>      */
>     public Contact(String name, String address) {
>       this.name = name;
>       this.address = address;
>     }
>
>     /**
>      * Return the name.
>      *
>      * @return The name of this contact.
>      */
>     public String getName() {
>       return name;
>     }
>
>     /**
>      * Return the address of this contact.
>      *
>      * @return The address.
>      */
>     public String getAddress() {
>       return address;
>     }
>   }
> }
>
> at least on my IDE
>
> Best,
>
> Ernesto
>
> On Sat, Nov 7, 2009 at 9:42 AM, Philip Johnson <johnson@...> wrote:
>
>> Greetings, Wicket Wizards,
>>
>> I am updating a sample Wicket program from 1.3.6 to 1.4.3 and running into
>> a few generics-related issues.   I am hoping you folks can quickly set me
>> straight. My code appears to run successfully and passes its JUnit tests,
>> despite the warnings I would like to remove.  The purpose of the code is to
>> demonstrate simple use of Forms, Lists, and Tables and associated testing of
>> these constructs using WicketTester.
>>
>> First off, although you hopefully will not need to, you can download the
>> sample code from here:
>> <
>> http://ics-wicket-examples.googlecode.com/files/wicket-example02-1.0.1106.zip
>> >
>>
>> Unzip, cd into the directory, and type "ant", It should download Ivy, then
>> download Wicket, Jetty, SLF4J, and JUnit, and finally compile the system,
>> generating the following generic-related warnings.   Let me now show you
>> what they are:
>>
>> Problem 1:  please take a look at line 39 of TablePage.java:
>> <
>> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java
>> >
>>
>> The problematic line is:
>> new ListDataProvider(contacts)
>>
>> and obviously requires a generic argument, but neither of the following
>> work:
>>  new ListDataProvider<Contact>(contacts)  // my preferred guess
>>  new ListDataProvider<List<Contact>>(contacts)
>>
>> The compiler warning is:
>>   [javac] TablePage.java:39: warning: [unchecked] unchecked call to
>> ListDataProvider(java.util.List<T>) as a member of the raw type
>> org.apache.wicket.markup.repeater.data.ListDataProvider
>>   [javac]         new ListDataProvider(contacts)) {
>>   [javac]         ^
>>   [javac] TablePage.java:39: warning: [unchecked] unchecked conversion
>>   [javac] found   :
>> org.apache.wicket.markup.repeater.data.ListDataProvider
>>   [javac] required:
>> org.apache.wicket.markup.repeater.data.IDataProvider<java.util.List<edu.hawaii.wicket.TablePage.Contact>>
>>   [javac]         new ListDataProvider(contacts)) {
>>   [javac]         ^
>>
>> Problem 2:  on line 49 of the same file, TablePage.java:
>> <
>> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TablePage.java
>> >
>>
>> The line is:
>> Contact contact = (Contact) item.getModelObject();
>>
>> Since the preceding line provides a parameterized declaration of  item
>> (Item<List<Contact>> item), I don't understand why I need to cast here. But
>> the code does not compile if I don't.  Then, I get the following warning:
>>
>>   [javac] TablePage.java:49: warning: [unchecked] unchecked cast
>>   [javac] found   : java.util.List<edu.hawaii.wicket.TablePage.Contact>
>>   [javac] required: edu.hawaii.wicket.TablePage.Contact
>>   [javac]         Contact contact = (Contact) item.getModelObject();
>>   [javac]
>>                                                ^
>>
>> Problem 3:  WicketTester and generics.
>>
>> I clearly don't understand how to test with WicketTester.  Take a look at
>> lines 37-39 of TestListPage:
>> <
>> http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TestListPage.java
>> >
>>
>> This is a mess, and generates the following warning:
>>   [javac] TestListPage.java:39: warning: [unchecked] unchecked cast
>>   [javac] found   : capture#294 of ?
>>   [javac] required: java.util.List<java.lang.String>
>>   [javac]     List<String> metaVars = (List<String>)
>> varsModel.getObject();
>>
>> I have a feeling that my whole approach to getting values out of the table
>> for testing is wrong, but I don't know what the correct approach is.
>>
>> If any of you can give me a hand, the first Mai Tai is on me the next time
>> you are in Hawaii.
>>
>> Thanks!
>> Philip
>>
>>
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@...
>> For additional commands, e-mail: users-help@...
>>
>>
>

[PhilipJohnson]

Thanks so much, both of you!

Anyone have any ideas about the WicketTester code?

Problem 3:  WicketTester and generics.

I clearly don't understand how to test with WicketTester.  Take a look at lines 37-39 of TestListPage:
<http://code.google.com/p/ics-wicket-examples/source/browse/trunk/example02/src/edu/hawaii/wicket/TestListPage.java>

This is a mess, and generates the following warning:
    [javac] TestListPage.java:39: warning: [unchecked] unchecked cast
    [javac] found   : capture#294 of ?
    [javac] required: java.util.List<java.lang.String>
    [javac]     List<String> metaVars = (List<String>) varsModel.getObject();


Cheers,
Philip