Default value of boolean and Boolean in Java

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What are the default values of boolean  primitive  and Boolean  primitive wrapper  in Java

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The default value of any Object  such as Boolean  is null   The default value for a boolean is false   Note  Every primitive has a wrapper class  Every wrapper uses a reference which has a default of null  Primitives have different default values   boolean - gt  false  byte  char  short  int  long - gt  0  float  double - gt  0 0   Note  2   void has a wrapper Void which also has a default of null and is it s only possible value  without using hacks

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boolean Can be true or false  Default value is false    Source  Java Primitive Variables   Boolean Can be a Boolean object representing true or false  or can be null  Default value is null

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If you need to ask  then you need to explicitly initialize your fields variables  because if you have to look it up  then chances are someone else needs to do that too   The value for a primitive boolean is false as can be seen here   As mentioned by others the value for a Boolean will be null by default

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Boolean is an Object   So if it s an instance variable it will be null   If it s declared within a method you will have to initialize it  or there will be a compiler error   If you declare as a primitive i e  boolean   The value will be false by default if it s an instance variable  or class variable    If it s declared within a method you will still have to initialize it to either true or false  or there will be a compiler error

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An uninitialized Boolean member  actually a reference to an object of type Boolean  will have the default value of null   An uninitialized boolean  primitive  member will have the default value of false

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class BooleanTester       boolean primitive      Boolean object       public static void main String   args            BooleanTester booleanTester   new BooleanTester            System out println  primitive      booleanTester getPrimitive             System out println  object      booleanTester getObject            public boolean getPrimitive             return primitive             public Boolean getObject             return object            output    primitive  false object  null   This seems obvious but I had a situation where Jackson  while serializing an object to JSON  was throwing an NPE after calling a getter  just like this one  that returns a primitive boolean which was not assigned  This led me to believe that Jackson was receiving a null and trying to call a method on it  hence the NPE  I was wrong   Moral of the story is that when Java allocates memory for a primitive  that memory has a value even if not initialized  which Java equates to false for a boolean  By contrast  when allocating memory for an uninitialized complex object like a Boolean  it allocates only space for a reference to that object  not the object itself - there is no object in memory to refer to - so resolving that reference results in null   I think that strictly speaking   defaults to false  is a little off the mark  I think Java does not allocate the memory and assign it a value of false until it is explicitly set  I think Java allocates the memory and whatever value that memory happens to have is the same as the value of  false   But for practical purpose they are the same thing

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There is no default for Boolean  Boolean must be constructed with a boolean or a String  If the object is unintialized  it would point to null   The default value of primitive boolean is false   http   download oracle com javase 6 docs api java lang Boolean html https   docs oracle com javase tutorial java nutsandbolts datatypes html

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The default value for a Boolean  object  is null  The default value for a boolean  primitive  is false

[java] Default value of 'boolean' and 'Boolean' in Java

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