Class NullPointerException

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.lang.NullPointerException

All Implemented Interfaces:

Serializable

public class NullPointerException
extends RuntimeException

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. NullPointerException objects may be constructed by the virtual machine as if suppression were disabled and/or the stack trace was not writable.

Since:

1.0

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
NullPointerException()	Constructs a NullPointerException with no detail message.
NullPointerException(String s)	Constructs a NullPointerException with the specified detail message.

Method Summary

Modifier and Type	Method	Description
String	getMessage()	Returns the detail message string of this throwable.

Methods declared in class Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Modifier and Type	Method	Description
final void	addSuppressed(Throwable exception)	Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.
Throwable	fillInStackTrace()	Fills in the execution stack trace.
Throwable	getCause()	Returns the cause of this throwable or null if the cause is nonexistent or unknown.
String	getLocalizedMessage()	Creates a localized description of this throwable.
StackTraceElement[]	getStackTrace()	Provides programmatic access to the stack trace information printed by Throwable.printStackTrace().
final Throwable[]	getSuppressed()	Returns an array containing all of the exceptions that were suppressed, typically by the try-with-resources statement, in order to deliver this exception.
Throwable	initCause(Throwable cause)	Initializes the cause of this throwable to the specified value.
void	printStackTrace()	Prints this throwable and its backtrace to the standard error stream.
void	printStackTrace(PrintStream s)	Prints this throwable and its backtrace to the specified print stream.
void	printStackTrace(PrintWriter s)	Prints this throwable and its backtrace to the specified print writer.
void	setStackTrace(StackTraceElement[] stackTrace)	Sets the stack trace elements that will be returned by Throwable.getStackTrace() and printed by Throwable.printStackTrace() and related methods.
String	toString()	Returns a short description of this throwable.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this 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.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

NullPointerException

public NullPointerException()

Constructs a NullPointerException with no detail message.

NullPointerException

public NullPointerException(String s)

Constructs a NullPointerException with the specified detail message.

Parameters:

s - the detail message.

Method Details

getMessage

public String getMessage()

Returns the detail message string of this throwable.

If a non-null message was supplied in a constructor it is returned. Otherwise, an implementation specific message or null is returned.

Overrides:

getMessage in class Throwable

Implementation Note:

If no explicit message was passed to the constructor, and as long as certain internal information is available, a verbose description of the null reference is returned. The internal information is not available in deserialized NullPointerExceptions.

Returns:

the detail message string, which may be null.