#nullpointerexception

How to Solve Java.lang.NullPointerException Error

Java protects application performance by using pointers to other memory locations when Objects are stored within an application. However, that means we have to check to see if an address is available before use. #java #syntax #null #NullPointerException

💚 TIP: References Quick List Java Types, Values and Variables Javadoc: NullPointerException Table of Contents Table of ContentsIntroductionJava PrimitivesJava Objects The Meaning of nullSafe Guards for null ValuesNull Pointer ExceptionsThrowing A NullPointerExceptionNullPointerExceptions Thrown by JavaSummary Introduction When we create new Objects, Java may be able to figure out what size…

according to the documentation, the method String.valueOf(Object obj) returns:

if the argument is null, then a string equal to "null"; otherwise, the value of obj.toString() is returned.

But how come when I try do this:

System.out.println("String.valueOf(null) = " + String.valueOf(null));

it throws NPE instead? (try it yourself if you don’t believe!)

Exception in thread "main"…

Gracefully avoiding NullPointerException in Java

Consider this line:

if (object.getAttribute("someAttr").equals("true")) { // ....

Obviously this line is a potential bug, the attribute might be null and we will get a NullPointerException. So we need to refactor it to one of two choices:

First option:

if ("true".equals(object.getAttribute("someAttr"))) { // ....

Second option:

String attr = object.getAttribute("someAttr"); if (attr != null)…