Compare null in java

So whenever you call a method with unitialized object which is a null object then it will throw NullPointerException. In your case, there is possibility that your String status is not initialized So you need to make it sure. BTW you should check null without using equals method because it doesn't make sense that you are checking a null object's method for its null value. You must do like this. Just for the info while using equals , try to use it like "anyValue".

By this you are just checking if value content of status variable is "null" String or not. IF you want to do a null check you need to do the following. This is exactly the reason why the HashMap cannot store more than one null values. Because it always compares the key with other valuues and if a null is inputted the second time , it throws NPE.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. NullPointerException when comparing with null values in java [duplicate] Ask Question. Asked 8 years, 5 months ago. Active 8 years, 5 months ago. Reference Materials String. Start Learning Java. Explore Java Examples. Multiply two Floating Point Numbers. Compute Quotient and Remainder.

Swap Two Numbers. Check Whether a Number is Even or Odd. Check Whether an Alphabet is Vowel or Consonant. Related Topics Java String isEmpty. Java String contains. Originally posted by Murali Nanchala: Exactly, whatever is sending the parameter in, is sending a String "null" instead of a null String Object.

Originally posted by Jim Yingst: If you want to ask about why you get a NullPointerException, please show code that actually throws a NullPointerException, and show the stack trace you get. Using the code shown so far the problem is clearly a NumberFormatException caused by the fact that the string "null" is not a number.

I don't get any NullPointerException in my stack traces here. Forum: Java in General. How to compare String with null??

R K Singh. I like Optional 'thank-you' note:. Very simple question, but just want to share with you all. First time I have to compare null like this: if myString. I cant recollect what was the exact problem. But we had lot of problem in running our code on JRun. Is Java becoming like C?? Write server dependent code.

Trelan Hylton. Thomas Paul. It is no different than asking if mystring. Joel McNary. Another more likely? Jim Yingst. Good point, Joel. Looks like this is the case as I am using Tomcat inside the eclipse.

So when I start the Tomcat, it runs inside the Eclipse. Thanks for your input. And then there's the minor detail that since equals is a method, if you try to invoke it on a null reference, you'll get a NullPointerException. Since Java 1. This class consists of static utility methods for operating on objects. These utilities include null-safe or null-tolerant methods for computing the hash code of an object, returning a string for an object, and comparing two objects.

If an Object variable is null, one cannot call an equals method upon it, thus an object reference check of null is proper. If you try calling equals on a null object reference, then you'll get a null pointer exception thrown.

According to sources it doesn't matter what to use for default method implementation:. EDIT: here is the org. Because equal is a function derived from Object class, this function compares items of the class. You code breaks Demeter's law. That's why it's better to refactor the design itself. As a workaround, you can use Optional.

This will first check the object reference and then check the object itself providing the reference isnt null. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 11 years ago. Active 1 year, 6 months ago. Viewed k times. Hubert Kario Jim Jeffries Jim Jeffries 9, 13 13 gold badges 58 58 silver badges bronze badges.

The easiest thing is to try null checking with equals and see. When you try it will instantly be obvious — Goran Jovic. By the way, a google search with keywords "java null check" without quotes gave me as one of the top hits this thread , which has the same info as the answers here. Add a comment.