java.lang.NullPointerException in Java
In Java “java.lang.NullPointerException” exception is the one that every beginner face once a while. The reason is variable at which the error occurred, does not contain any value or object reference.
1. If u define any reference variable and don’t create any object for that variable
2. If u define any reference variable globally but when u create the object then again define it
Object a; // declare an object a.hashcode(); // trying to call a method on the object. //"mind it! I have not initialized it yet" // above line will definitely give you an exception, //obviously NullPointerException as reference a is still null.
Object a; // declare an object a=new Object(); //initialized, Yes! you can do it on above line as will a.hashcode();
Wanna deep dive? Go here