Be careful nullpointerexception

Nullpointerexception

It's so ubiquitous that I ran it out accidentally.

Debugging is required for the victim for half a day.

 

Note the following secret points:

For example, for native type encapsulation such as integer, they can be used in the place where native types are used, and they will be implicitly converted by themselves. However, if the conversion is null before the conversion, it will be a tragedy, the nullpointerexception is thrown.

 

For example

Void func (int ){}

 

 

Integer A = NULL;

Func ();

 

At this time, a null pointer exception will be thrown in func (a); it will be silly if you have never experienced it...

 

 

PS:

I have never written a blog for a long time.

There is also a photography blog, which has not been updated for a long time. Even if you are free, you can take the camera everywhere...

Address:

Http://lifangeye.blogbus.com/

Lifangeye ......CubeWatching the world, haha

Is it better to lifangview... poor English...