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Generics

 
Suguna Gollapally
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Posts: 37
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import java.util.*;
class shape { }
class Rect extends shape { }
class cir extends shape { }
class shade extends Rect{}
class Test {

public static void add(List<? extends shape>l,int pos,Rect r) {

l.add(pos,r);
}

public static void main(String ar[]) {

List<shade>=new ArrayList<shade>();
add(l,o,newshade());
}
}
What is the error in this program?? is this add() method..
 
Keith Lynn
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Originally posted by Suguna Gollapally:
import java.util.*;
class shape { }
class Rect extends shape { }
class cir extends shape { }
class shade extends Rect{}
class Test {

public static void add(List<? extends shape>l,int pos,Rect r) {

l.add(pos,r);
}

public static void main(String ar[]) {

List<shade>=new ArrayList<shade>();
add(l,o,newshade());
}
}
What is the error in this program?? is this add() method..


Because the parameter to the method accepts a List containing shape or anything that extends shape, there is no way to allow anything to be added to the List in the method.
 
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