How do I inherit from a generic class in java? -

i have class following

public class foo<idtype extends writablecomparable<idtype>, edata extends writable> {   public foo();    public foo(idtype foo; idtype bar){   this.foo = foo;   this.bar = bar;   }   private idtype foo;   private idtype bar;  } 

now 1 of usage of class following:

elist = new arraylist<foo<stringtype, emptytype>>(); 

so works fine:

now want extend class add 1 more field

private string foobar;

now, instance of have 3 fields.

two of them

   foobar.foo //base class    foobar.bar //base class    foobar.foobar // new variable added 

now, usage still same:

 elist = new arraylist<foobar<stringtype, emptytype>>(); 

i tried simple extension:

 public class foobar extends foo{  private string foobar;  public foobar(string foobar){this.foobar = foobar;} 

}

but when use

i error:

 elist = new arraylist<foobar<stringtype, emptytype>>(); arraylist<foobar><stringtype,emptytype>> cannot resolved type 

if want let user specify types subclass, specify same type parameters, , pass them on base:

public class foobar <idtype extends writablecomparable<idtype>, edata extends writable>     extends foo<idtype, edata> {      ... } 

if want let user specify 1 of types, can that, e.g. want force integer idtype:

public class foobar <edata extends writable>     extends foo<integer, edata> {      ... } 

if want use specific types base, same idea:

public class foobar     extends foo<integer, something> {      ... } 

you can add type:

public class foobar <idtype extends writablecomparable<idtype>, edata extends writable, anothertype>     extends foo<idtype, edata> {      private anothertype x;     ... } 

the point is, specify own parameter types in subclass in way see fit, , can pass types base long compatible types.

edit: responding comment on question above, have specify constraints on foobar type parameters match constraints on base foo. example, following not sufficient:

public class foobar <idtype, edata>     extends foo<idtype, edata> // <-- fail compile {      ... } 

this lead following compilation errors:

type parameter idtype not within bound type parameter edata not within bound 

this because foo expects types extend writablecomparable<idtype> , writable, respectively, above erroneous declaration of foobar attempts pass types not meet constraints type parameters foo.

your error, way, posted, not appear match code , has > @ end. appears made typo when copying , pasting.