string.equals(null) vs string == null [duplicate]

Question

I've seen some of this answered for PHP, SQL and C++, but can't find by java. There is some convention or best practice with that?

I'm asking about null not equals vs ==

if (myString != null && myString == null)

or

if (!myString.equals(null) && myString.equals(null))

Here is the answer I think: stackoverflow.com/questions/4501061/… — marc3l
– marc3l, Commented May 21, 2015 at 9:18
It is the answer for your null. Equals will throw a NullPointerException in your case. — marc3l
– marc3l, Commented May 21, 2015 at 9:19
if myString == null, myString.equals(null) throw null pointer .. — Hacketo
– Hacketo, Commented May 21, 2015 at 9:19
Because if it's null, it's like writing null.equals(null). — Maroun
– Maroun, Commented May 21, 2015 at 9:22

Yuri · Accepted Answer · 2015-05-21 09:20:03Z

7

mystring == null, if mystring would actually be null it would throw an exception, because you are trying to access its equals method.

answered May 21, 2015 at 9:20

Yuri

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2 Comments

Hacketo Over a year ago

And if you don't want to care about checking null before check a string value , you can do "astring".equals(myString)

JimLohse Over a year ago

This answer gives good additional reasons why not to use .equals, even if OP is specifically not asking about it :) stackoverflow.com/a/4501084/3255525

Zereges · Accepted Answer · 2015-05-21 09:22:05Z

1

If myString is not null, myString.equals(null) is false by definition. If it is null, it will throw NullPointerException.

If you want to check whether myString is null, you have to check it by myString == null;

answered May 21, 2015 at 9:22

Zereges

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Comments

Michael Lloyd Lee mlk · Accepted Answer · 2015-05-21 09:21:32Z

0

if (!myString.equals(null) && myString.equals(null))

Would not work as you are attempting to call a method (.equals) on the the none-existent object myString.

answered May 21, 2015 at 9:21

Michael Lloyd Lee mlk

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