NullPointerException

Class Overview

Thrown when an application attempts to use null in a case where an object is required. These include:

• Calling the instance method of a null object.
• Accessing or modifying the field of a null object.
• Taking the length of null as if it were an array.
• Accessing or modifying the slots of null as if it were an array.
• Throwing null as if it were a Throwable value.

Applications should throw instances of this class to indicate other illegal uses of the null object.

Summary

[Expand] Inherited Methods
From class java.lang.Throwable String getMessage() Returns the error message string of this throwable object. void printStackTrace() Prints this Throwable and its backtrace to the standard error stream. String toString() Returns a short description of this throwable object.
From class java.lang.Object boolean equals(Object obj) Indicates whether some other object is "equal to" this one. final Class<?> getClass() Returns the runtime class of an object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeout, int nanos) Causes current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed. final void wait(long timeout) Causes current thread to wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed. final void wait() Causes current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object.