Java primitive types (such as int , double , or float ) cannot have null values , which you must consider in choosing your result expression and host expression types.
Read moreHow do you check if an object is a double in Java?
As Java is a statically typed language, you always know if something is a double at compile time. That also means that the if statement is completely unnecessary. If the variable v is possibly of type Double (the wrapped type of double ) then you can simply use v instanceof Double to check.
Read moreIs object null Java?
Is null an Object in Java? No it’s not , and for those who wonder why such a question, there are languages where null is indeed an object like any, for example Ruby. In Scala, which is very meticulous about types, there is a type Null (a trait, actually) having a single instance null .
Read moreIs == null in Java?
7. == and != The comparison and not equal to operators are allowed with null in Java . This can made useful in checking of null with objects in java.
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