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## java.lang
Class ClassNotFoundException

    java.lang.Object
      |
      +--java.lang.Throwable
            |
            +--java.lang.Exception
                  |
                  +--java.lang.ClassNotFoundException

All Implemented Interfaces:
  Serializable

public class ClassNotFoundException
extends Exception

Thrown when an application tries to load in a class through its string name using:

- The `forName` method in class `Class`.
- The `findSystemClass` method in class `ClassLoader` .
- The `loadClass` method in class `ClassLoader`.

but no definition for the class with the specified name could be found.

As of release 1.4, this exception has been retrofitted to conform to the general purpose exception-chaining mechanism. The "optional exception that was raised while loading the class" that may be provided at construction time and accessed via the `getException()` method is now known as the cause, and may be accessed via the `Throwable.getCause()` method, as well as the aforementioned "legacy method."

Since:
  JDK1.0
See Also:
  `Class.forName(java.lang.String)`, `ClassLoader.findSystemClass(java.lang.String)`, `ClassLoader.loadClass(java.lang.String, boolean)`, Serialized Form

Constructor Summary
`ClassNotFoundException()` Constructs a `ClassNotFoundException` with no detail message.
`ClassNotFoundException(String s)` Constructs a `ClassNotFoundException` with the specified detail message.
`ClassNotFoundException(String s, Throwable ex)` Constructs a `ClassNotFoundException` with the specified detail message and optional exception that was raised while loading the class.

Method Summary
`Throwable` | `getCause()` Returns the the cause of this exception (the exception that was raised if an error occurred while attempting to load the class; otherwise `null`).
`Throwable` | `getException()` Returns the exception that was raised if an error occurred while attempting to load the class.

Methods inherited from class java.lang.Throwable
`fillInStackTrace, getLocalizedMessage, getMessage, getStackTrace, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### ClassNotFoundException

    public ClassNotFoundException()

  Constructs a `ClassNotFoundException` with no detail message.

### ClassNotFoundException

    public ClassNotFoundException(String s)

  Constructs a `ClassNotFoundException` with the specified detail message.

Parameters:
  `s` - the detail message.

### ClassNotFoundException

    public ClassNotFoundException(String s,
                                  Throwable ex)

  Constructs a `ClassNotFoundException` with the specified detail message and optional exception that was raised while loading the class.

Parameters:
  `s` - the detail message
  `ex` - the exception that was raised while loading the class
Since:
  1.2

Method Detail

### getException

    public Throwable getException()

  Returns the exception that was raised if an error occurred while attempting to load the class. Otherwise, returns `null`.

  This method predates the general-purpose exception chaining facility. The `Throwable.getCause()` method is now the preferred means of obtaining this information.

  Returns:
    the `Exception` that was raised while loading a class
  Since:
    1.2

### getCause

    public Throwable getCause()

  Returns the the cause of this exception (the exception that was raised if an error occurred while attempting to load the class; otherwise `null`).

  Overrides:
    `getCause` in class `Throwable`
  Returns:
    the cause of this exception.
  Since:
    1.4

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.