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# Class java.lang.NullPointerException

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

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()
  Constructs a `NullPointerException` with no detail message.
NullPointerException(String)
  Constructs a `NullPointerException` with the specified detail message.

##

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.

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