A NullPointerException in Java is thrown when an object is expected as a parameter, but null is passed instead. To avoid this when doing String comparisons, use Object.equals instead.
The method signatures for equals() and equalsIgnoreCase() are different (the former accepts an Object as a parameter and the latter accepts a String ), but they both return a boolean primitive value.
This code will throw a NullPointerException if stringTwo is set to null:
This code serves the same function and doesn’t throw the exception.