How do I test null keys on any Java map implementation?
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Java
I want to make sure that the map passed to the method as a parameter does not contain a null key People will think that the following situations will:
if ( map.containsKey(null) ) …
However, if the method passed is similar to treemap, it will be broken. According to the general Java map contract, it is free to reject null keys with a NPE
Do we have a reasonable way to test null keys while accepting any map implementation?
Solution
boolean hasAnyNull = yourMap.keySet()
boolean hasAnyNull = yourMap.keySet() .stream() .anyMatch(Objects::isNull);
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