java.lang.NullPointerException with boolean

by

null cannot be auto-unboxed to a primitive boolean value, which is what happens when you try to compare it with true. In 

param == true

The type of true is boolean, therefore the left-hand operand must also be a boolean. You are passing in a Boolean, which is an object, but can be auto-unboxed to boolean.

Therefore this is equivalent to

param.booleanValue() == true

Clearly, if param is null, the above throws NullPointerException.

To avoid the hidden pitfalls of auto-unboxing, you could instead work with the Boolean objects:

if (Boolean.TRUE.equals(param))
  return "a";
if (Boolean.FALSE.equals(param))
  return "b";
return "c";

More Related Contents:

  1. Can't call method from class 1 in class 2 [closed]
  2. How to create a loop thats includes a if statement
  3. Java Questions! About List and Objects
  4. The syntax of the method [closed]
  5. nothing happens when i execute the code. Got my methods right? [closed]
  6. Is it possible to change the return value of a method in this case? [closed]
  7. Java Array Parameter and Array Type Metot [closed]
  8. Variable may not of been initialized even though it has been in the method
  9. Which overload will get selected for null in Java?
  10. Java synchronized static methods: lock on object or class
  11. Why does this Java method appear to have two return types?
  12. Why doesn’t Mockito mock static methods?
  13. Converting Integers to Roman Numerals – Java
  14. Should private helper methods be static if they can be static
  15. Set and Get Methods in java?
  16. Count words in a string method?
  17. How do I intercept a method invocation with standard java features (no AspectJ etc)?
  18. Are there any Java method ordering conventions? [closed]
  19. Compiler error : reference to call ambiguous
  20. If statement using == gives unexpected result [duplicate]
  21. Can non-static methods modify static variables
  22. What does ‘public static void’ mean in Java?
  23. Varargs Java Ambiguous Call
  24. Java: Sending Multiple Parameters to Method [closed]
  25. Java Inheritance – calling superclass method
  26. Final arguments in interface methods – what’s the point?
  27. How can I create a Java method that accepts a variable number of arguments?
  28. Naming conventions for Java methods that return boolean
  29. Why does this generic java method accept two objects of different type?
  30. Static method in Java can be accessed using object instance [duplicate]

Leave a Comment