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javanullguavapredicatenotnull

All Null, Any Null is possible guava Predicate

I'm currently facing a code readability issue. The problem is the following:

Have three objects

// initialization skipped, all of three could be null as result of their initalization
Object obj1;
Object obj2;
Object obj3;

I want to create two booleans from them as follows:

// all are null
boolean bool1 = (obj1 == null && obj2 == null && obj3 == null); 

// any of them is null

boolean bool2 = (obj1 == null || obj2 == null || obj3 == null);

I know guava provides built-in predicates like isNull and notNull.

Is there a way to implement a custom predicate that fulfills those two booleans? (assuming that .apply(..) function would take 3 parameters then)

Solution

  • I'm not sure what you want, but the answer is most probably: Yes, but it makes little sense.

    You can use

    FluentIterable<Object> it =
    FluentIterable.from(Lists.newArrayList(obj1, obj2, obj3));

boolean allNull = it.allMatch(Predicates.isNull());
boolean anyNull = it.anyMatch(Predicates.isNull());

    but be assured that it's both much less readable and much slower than doing it the normal way.