问题
What are the default values of boolean (primitive) and Boolean (primitive wrapper) in Java?
回答1:
The default value for a Boolean (object) is null.
The default value for a boolean (primitive) is false.
回答2:
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 -> false
byte, char, short, int, float -> 0
float, double -> 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).
回答3:
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.
回答4:
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.
回答5:
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.
回答6:
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.
回答7:
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
来源：https://stackoverflow.com/questions/6226290/default-value-of-boolean-and-boolean-in-java