instance_of.java

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package test.java.semantics;
 
import java.util.List;
 
//hmmm: convert this to simple unit test.
class instance_of
{
  public instance_of()
  {
  }
 
  public Object cogitate()
  {
    return null;
  }
 
  public static void main(String s[]) throws Exception
  {
    // we are just asserting that it is safe to do instanceof on an object that is null.
    // let's test that theory.
    instance_of tony = new instance_of();
    Object fred = tony.cogitate(); // will produce null.
    if (fred instanceof List<?>) {
      throw new Exception("FAILURE!  fred should not be instance of List<?> !  null is an instance of something!");
    } else {
      System.out.println("told us null is not an instance of List, which is correct.");
    }
  }
}