Check if null Boolean is true results in exception

Question

I have the following code   Boolean bool   null   try        if  bool                  DoSomething                             catch  Exception e         System out println e getMessage                      Why does my check up on the Boolean variable  bool  result in an exception  Shouldn t it just jump right past the if statement when it  sees  that it isn t true  When I remove the if statement or check up on if it s NOT null  the exception goes away

User · Accepted Answer

When you have a boolean it can be either true or false  Yet when you have a Boolean it can be either Boolean TRUE  Boolean FALSE or null as any other object   In your particular case  your Boolean is null and the if statement triggers an implicit conversion to boolean that produces the NullPointerException  You may need instead   if bool    null  amp  amp  bool

User · Answer

as your variable bool is pointing to a null  you will always get a NullPointerException  you need to initialize the variable first somewhere with a not null value  and then modify it

User · Answer

Boolean is the object wrapper class for the primitive boolean  This class  as any class  can indeed be null  For performance and memory reasons it is always best to use the primitive   The wrapper classes in the Java API serve two primary purposes    To provide a mechanism to    wrap    primitive values in an object so that the primitives can be included in activities reserved for objects  like as being added to Collections  or returned from a method with an object return value   To provide an assortment of utility functions for primitives  Most of these functions are related to various conversions  converting primitives to and from String objects  and converting primitives and String objects to and from different bases  or radix   such as binary  octal  and hexadecimal    http   en wikipedia org wiki Primitive wrapper class

User · Answer

Or with the power of Java 8 Optional  you also can do such trick   Optional ofNullable boolValue  orElse false

User · Answer

Use the Apache BooleanUtils    If peak performance is the most important priority in your project then look at one of the other answers for a native solution that doesn t require including an external library    Don t reinvent the wheel  Leverage what s already been built and use isTrue      BooleanUtils isTrue  bool      Checks if a Boolean value is true  handling null by returning false   If you re not limited to the libraries you re  allowed  to include  there are a bunch of great helper functions for all sorts of use-cases  including Booleans and Strings  I suggest you peruse the various Apache libraries and see what they already offer

User · Answer

Boolean types can be null  You need to do a null check as you have set it to null    if  bool    null  amp  amp  bool        DoSomething

User · Answer

If you don t like extra null checks   if  Boolean TRUE equals value

[java] Check if null Boolean is true results in exception

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