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Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class NullPointerException - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.lang
Class NullPointerException

java.lang.Object
  |
  +--java.lang.Throwable
        |
        +--java.lang.Exception
              |
              +--java.lang.RuntimeException
                    |
                    +--java.lang.NullPointerException

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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.

Since:

JDK1.0

See Also:

Serialized Form

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Constructor Summary

NullPointerException()           Constructs a NullPointerException with no detail message.

NullPointerException(String s)           Constructs a NullPointerException with the specified detail message.

 

Methods inherited from class java.lang.Throwable

fillInStackTrace, getLocalizedMessage, getMessage, printStackTrace, printStackTrace, printStackTrace, toString

 

Methods inherited from class java.lang.Object

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

 

Constructor Detail

NullPointerException

public NullPointerException()

Constructs a NullPointerException with no detail message.

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NullPointerException

public NullPointerException(String s)

Constructs a NullPointerException with the specified detail message.

Parameters:

s - the detail message.

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