Databases
StackOverflow2013
Postsdbo
POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
    primarykey
    data
    text
    <p>I'm attempting to iterate a <code>List</code> of objects. like so.. </p> <pre><code>for(System s : usersSystems){ } </code></pre> <p>Where <code>usersSystems</code> is of type <code>List&lt;UserSystems&gt;</code>. <code>usersSystems</code> is a fairly simple class simply consisting of a constructor...</p> <pre><code>public UsersSystems(System system,int ID) { this.system = system; this.ID = ID; } </code></pre> <p>Assigning <code>usersSystems</code> is done by making it equal to <code>user.sources</code> which is initialized and given a default value in the <code>User</code> constructor. Below is my stacktrace. Why am I getting the above error and how do I correct it?</p> <pre><code>play.exceptions.JavaExecutionException: java.util.LinkedHashMap cannot be cast to models.Systems at play.mvc.ActionInvoker.invoke(ActionInvoker.java:227) at Invocation.HTTP Request(Play!) Caused by: java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to models.Systems at controllers.Start.starting(Start.java:40) at play.mvc.ActionInvoker.invokeWithContinuation(ActionInvoker.java:540) at play.mvc.ActionInvoker.invoke(ActionInvoker.java:498) at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:474) at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:469) at play.mvc.ActionInvoker.invoke(ActionInvoker.java:157) ... 1 more </code></pre> <p><strong>EDIT:</strong></p> <p><strong>UserSystem</strong></p> <pre><code>@Entity public class UsersSystem extends Model{ public int ID; public System system; public UsersSystem(System system, int ID) { this.source = source; this.ID = ID; } } </code></pre> <p><strong>SYSTEM</strong></p> <pre><code>@Entity public class System extends Model{ private String name; private int ID; public System(String name, int ID){ this.name = name; this.ID = ID; } } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USuser596186
    1. USuser596186
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
      1. This table or related slice is empty.
      1. VTUndeletion
    1. COYou first say that your list holds System instances. Then you tell us that System is a simple class with a constructor, and show us the constructor of a class named UserSystems (and not System). And finally, your list, according to the exception contains LinkedHashMap instances, and tries to cast it to Systems (with a final s). That makes four different types. You seem to be very confused with your types. And without seeing the code which instantiates and populates the list, it's impossible to tell you where the error is.
      singulars
      1. POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
      1. USJB Nizet
    2. CO@JBNizet Woops! I've clarified my question hopefully this makes more sense.
      singulars
      1. POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
      1. USuser596186
    3. COShow us the code. And does System extend UsersSystems, because if it's not, then the code you showed should not even compile?
      singulars
      1. POPlay-Framework: ClassCastException occured : java.util.LinkedHashMap cannot be cast to models.Systems
      1. USJB Nizet
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload