Auto boxing can fool you | skybert.net

Auto boxing can fool you


Assigning null objects to primitives

public class FalseSafetyWithAutoBoxing {
  private static class Car {
    public Car(Double price) {
      double value = price;
    }
  }

  public static void main(String[] args) throws Exception {
    Double price = null;
    Car car = new Car(price);
  }
}

When you run this, you get:

$ javac FalseSafetyWithAutoBoxing.java && java FalseSafetyWithAutoBoxing
Exception in thread "main" java.lang.NullPointerException
  at FalseSafetyWithAutoBoxing$Car.<init>(FalseSafetyWithAutoBoxing.java:12)
  at FalseSafetyWithAutoBoxing.main(FalseSafetyWithAutoBoxing.java:18)

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