Java String null and empty value processing __java

In the development process, the author often encountered the following errors in use:

1, Error usage one:

if (name = = "") {
Do something
}

2, Error usage two:
if (Name.equals ("")) {
Do something
}

3, Error usage three:
if (. Name.equals ("")) {
Do something

}

The above error usage 1 is the easiest for beginners, and the least likely to be found, because their syntax is no problem, the Java compiler compiles without error. However, this condition may cause a bug in the program at run time and will never be true, that is to say, the statement in the If block will never be executed.

The above usage two, usage Three's writing, is including many Java proficient also very easy to make the mistake, why is wrong. Maybe you'll be wondering.
Yes, the writing itself is correct, but, without a null judgment condition, imagine, if name=null, what will happen to the consequences? The consequence is that your program will throw NullPointerException exceptions, the system will be suspended and no longer provide normal service.
Of course, if you have previously made null judgments on name exceptions.

The correct wording should precede the condition of name!= NULL, as an example:

if (name!= null &&. Name.equals ("")) {
Do something
}