What is a null pointer exception in Java?
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What is a null pointer exception in Java?
Null Pointer Exception In Java. NullPointerException is a RuntimeException. In Java, a special null value can be assigned to an object reference. NullPointerException is thrown when program attempts to use an object reference that has the null value. These can be: Invoking a method from a null object.
When is it appropriate to throw a NullPointerException?
If the method is intended to do something to the passed-in object as the above method does, it is appropriate to throw the NullPointerExceptionbecause it’s a programmer error and the programmer will need that information for debugging purposes.
Why do I get a NullPointerException when I try to dereference NUM?
If you attempt to dereference num BEFORE creating the object you get a NullPointerException. In the most trivial cases, the compiler will catch the problem and let you know that “num may not have been initialized,” but sometimes you may write code that does not directly create the object.
How to avoid null pointer exception in J2EE?
In j2ee projects,Nullpointer exception is very common.Some cases reference variables got null values.So You should check the variable initialization properly.And during conditional statement you should always check that flag or reference contains null or not like:- if(flag!=0) { ur code that uses flag } – Amaresh Pattanayak Apr 17 ’15 at 12:58 17
How to replace getactionbar() with getsupportactionbar?
Update: In case you’re using the support library version of the Action Bar, you should replace getActionBar () with getSupportActionBar (). First off, you need to set the toolbar as the support ActionBar. Then if you’re certain it’s going to be there all the time, just assert it as != null.
How to avoid NullPointerException with the ternary operator?
The ternary operator can be used to avoid NullPointerException. First, the Boolean expression is evaluated. If the expression is true then, the value1 is returned, otherwise, the value2 is returned. We can use the ternary operator for handling null pointers:
