Java check if boolean is null

Question

How do you check if a boolean is null or not  So if I know  hideInNav  is null  How do I stop  it from further executing  Something like the below doesn t seem to work but why    boolean hideInNav   parent getProperties   get  hideInNav   false   String hideNavigation   hideInNav    null   hideInNav

User · Accepted Answer

boolean can only be true or false because it s a primitive datatype    a boolean variables default value is false   You can use the class Boolean instead if you want to use null values  Boolean is a reference type  that s the reason you can assign null to a Boolean  variable   Example   Boolean testvar   null  if  testvar    null

User · Answer

In Java  null only applies to object references  since boolean is a primitive type  it cannot be assigned null   It s hard to get context from your example  but I m guessing that if hideInNav is not in the object returned by getProperties    the  default value   you ve indicated will be false   I suspect this is the bug that you re seeing  as false is not equal to null  so hideNavigation is getting the empty string   You might get some better answers with a bit more context to your code sample

User · Answer

The only thing that can be a null is a non-primivite  A boolean which can only hold TRUE or FALSE is a primitive  The TRUE FALSE in memory are actually numbers  0 and 1   0   FALSE 1   TRUE  So when you instantiate an object it will be null String str     will equal null On the other hand if you instaniate a primitive it will be assigned to 0 default  boolean isTrue     will be 0 int i     will be 0

User · Answer

boolean is a primitive data type in Java and primitive data types can not be null like other primitives int  float etc  they should be containing default values if not assigned  In Java  only objects can assigned to null  it means the corresponding object has no reference and so does not contain any representation in memory  Hence If you want to work with object as null   you should be using Boolean class which wraps a primitive boolean type value inside its object   These are called wrapper classes in Java  For Example  Boolean bool   readValue          Read Your Value if  bool     null    do This

User · Answer

A boolean cannot be null in java   A Boolean  however  can be null   If a boolean is not assigned a value  say a member of a class  then it will be false by default

User · Answer

boolean is a primitive type  and therefore can not be null   Its boxed type  Boolean  can be null   The function is probably returning a Boolean as opposed to a boolean  so assigning the result to a Boolean-type variable will allow you to test for nullity

User · Answer

null is a value assigned to a reference type  null is a reserved value  indicating that a reference does not resemble an instance of an object   A boolean is not an instance of an Object  It is a primitive type  like int and float  In the same way that  int x has a value of 0  boolean x has a value of false

[java] Java check if boolean is null

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