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  1.  
  2. import java.util.ArrayList;
  3. import java.util.List;
  4.  
  5. public class Main {
  6.  
  7.     public interface Foo<T> {
  8.         T getValue();
  9.         void setValue(T value);
  10.     }
  11.  
  12.     public static class FooImpl<T> implements Foo<T> {
  13.  
  14.         private T value;
  15.  
  16.         public FooImpl(T value) {
  17.             this.value = value;
  18.         }
  19.  
  20.         @Override
  21.         public T getValue() {
  22.             return value;
  23.         }
  24.  
  25.         @Override
  26.         public void setValue(T value) {
  27.             this.value = value;
  28.         }
  29.     }
  30.  
  31.     public static <T> void resetFoos(Iterable<Foo<T>> foos) {
  32.         for (Foo<T> foo : foos) {
  33.             foo.setValue(foo.getValue());
  34.         }
  35.     }
  36.  
  37.     public static void main(String[] args) {
  38.  
  39.         final Foo<Object> objFoo = new FooImpl<>(new Object());
  40.         final Foo<Integer> numFoo = new FooImpl<>(new Integer(42));
  41.         final Foo<String> strFoo = new FooImpl<>("asdf");
  42.  
  43.         List<Foo<?>> foos = new ArrayList<>(3);
  44.         foos.add(objFoo);
  45.         foos.add(numFoo);
  46.         foos.add(strFoo);
  47.  
  48.         resetFoos(foos);
  49.  
  50.         System.out.println("done");
  51.     }
  52. }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
Main.java:48: error: method resetFoos in class Main cannot be applied to given types;
        resetFoos(foos);
        ^
  required: Iterable<Foo<T>>
  found: List<Foo<?>>
  reason: no instance(s) of type variable(s) T exist so that argument type List<Foo<?>> conforms to formal parameter type Iterable<Foo<T>>
  where T is a type-variable:
    T extends Object declared in method <T>resetFoos(Iterable<Foo<T>>)
1 error
stdout
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Standard output is empty
https://ideone.com/uUfDub
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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