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Editorial Team
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Asked: 2026-05-24T22:58:14+00:00

This is puzzling me and I would like an explanation. public foo(EventPoint… eventPoints) {

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This is puzzling me and I would like an explanation.

public foo(EventPoint... eventPoints) { 
  //...
}


boolean isThisHappening;

foo(isThisHappening ? new EventPoint() : new EventPoint[]{});

Even though foo(new EventPoint()); is valid and foo(new EventPoint[]{}); is also valid. Is this the ternary operator failing due to type evaluation?

Using JDK 1.7.0
Getting the error:
required: EventPoint[]
found: Object
reason: argument type Object does not conform to vararg element type EventPoint

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1 Answer

  1. Editorial Team

    Is this the ternary operator failing?

    The type of a ternary expression is basically the most specific subtype of the two last operands (JLS Reference). The most specific subtype of EventPoint and EventPoint[] is Object. If your var-arg method is declared to accept EventPoint... it simply won’t work.

    You should change 

    foo(state == ItemEvent.SELECTED ? (EventPoint) e.getItem()
                                : new EventPoint[]{});

    to

    foo(state == ItemEvent.SELECTED ? new EventPoint[] { (EventPoint) e.getItem() }
                                : new EventPoint[] { });

    and it should compile just fine.

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