java.lang.NullPointerException
In java many times you face a "java.lang.NullPointerException" exception in running a program. The reason is variable at which the error occurred does not contain any value or object.
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
ex. JButton btn; /* defined globally */
JButton btn=new JButton(); /* on the time of creating the object */
This will give an "java.lang.NullPointerException" when u run the program or pass any event on this button.
solution :-
1. btn= new JButton /* on the time of creating the object */
2. When u don't know then check that for your "object==null" if this is true then initialize object with some value
In java many times you face a "java.lang.NullPointerException" exception in running a program. The reason is variable at which the error occurred does not contain any value or object.
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
ex. JButton btn; /* defined globally */
JButton btn=new JButton(); /* on the time of creating the object */
This will give an "java.lang.NullPointerException" when u run the program or pass any event on this button.
solution :-
1. btn= new JButton /* on the time of creating the object */
2. When u don't know then check that for your "object==null" if this is true then initialize object with some value
