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## org.apache.commons.lang.exception
Class NestableDelegate

    java.lang.Object
      org.apache.commons.lang.exception.NestableDelegate

All Implemented Interfaces:
  Serializable

    public class NestableDelegate

extends Object
implements Serializable

A shared implementation of the nestable exception functionality.

The code is shared between `NestableError`, `NestableException` and `NestableRuntimeException`.

Since:
  1.0
Version:
  $Id: NestableDelegate.java 905636 2010-02-02 14:03:32Z niallp $
Author:
  Apache Software Foundation, Rafal Krzewski, Daniel L. Rall, Kasper Nielsen, Steven Caswell, Sean C. Sullivan
See Also:
  Serialized Form

Field Summary
`static boolean` | `matchSubclasses` Whether to match subclasses via indexOf.
`static boolean` | `topDown` Whether to print the stack trace top-down.
`static boolean` | `trimStackFrames` Whether to trim the repeated stack trace.

Constructor Summary
`NestableDelegate(Nestable nestable)` Constructs a new `NestableDelegate` instance to manage the specified `Nestable`.

Method Summary
`String` | `getMessage(int index)` Returns the error message of the `Throwable` in the chain of `Throwable`s at the specified index, numbered from 0.
`String` | `getMessage(String baseMsg)` Returns the full message contained by the `Nestable` and any nested `Throwable`s.
`String[]` | `getMessages()` Returns the error message of this and any nested `Throwable`s in an array of Strings, one element for each message.
`protected String[]` | `getStackFrames(Throwable t)` Captures the stack trace associated with the specified `Throwable` object, decomposing it into a list of stack frames.
`Throwable` | `getThrowable(int index)` Returns the `Throwable` in the chain of `Throwable`s at the specified index, numbered from 0.
`int` | `getThrowableCount()` Returns the number of `Throwable`s contained in the `Nestable` contained by this delegate.
`Throwable[]` | `getThrowables()` Returns this delegate's `Nestable` and any nested `Throwable`s in an array of `Throwable`s, one element for each `Throwable`.
`int` | `indexOfThrowable(Class type, int fromIndex)` Returns the index, numbered from 0, of the first `Throwable` that matches the specified type, or a subclass, in the chain of `Throwable`s with an index greater than or equal to the specified index.
`void` | `printStackTrace()` Prints the stack trace of this exception the the standar error stream.
`void` | `printStackTrace(PrintStream out)` Prints the stack trace of this exception to the specified stream.
`void` | `printStackTrace(PrintWriter out)` Prints the stack trace of this exception to the specified writer.
`protected void` | `trimStackFrames(List stacks)` Trims the stack frames.

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

Field Detail

### topDown

    public static boolean topDown

  Whether to print the stack trace top-down. This public flag may be set by calling code, typically in initialisation. This exists for backwards compatability, setting it to false will return the library to v1.0 behaviour (but will affect all users of the library in the classloader).

  Since:
    2.0

### trimStackFrames

    public static boolean trimStackFrames

  Whether to trim the repeated stack trace. This public flag may be set by calling code, typically in initialisation. This exists for backwards compatability, setting it to false will return the library to v1.0 behaviour (but will affect all users of the library in the classloader).

  Since:
    2.0

### matchSubclasses

    public static boolean matchSubclasses

  Whether to match subclasses via indexOf. This public flag may be set by calling code, typically in initialisation. This exists for backwards compatability, setting it to false will return the library to v2.0 behaviour (but will affect all users of the library in the classloader).

  Since:
    2.1

Constructor Detail

### NestableDelegate

    public NestableDelegate(Nestable nestable)

  Constructs a new `NestableDelegate` instance to manage the specified `Nestable`.

  Parameters:
    `nestable` - the Nestable implementation (must extend `Throwable`)
  Since:
    2.0

Method Detail

### getMessage

    public String getMessage(int index)

  Returns the error message of the `Throwable` in the chain of `Throwable`s at the specified index, numbered from 0.

  Parameters:
    `index` - the index of the `Throwable` in the chain of `Throwable`s
  Returns:
    the error message, or null if the `Throwable` at the specified index in the chain does not contain a message
  Throws:
    `IndexOutOfBoundsException` - if the `index` argument is negative or not less than the count of `Throwable`s in the chain
  Since:
    2.0

### getMessage

    public String getMessage(String baseMsg)

  Returns the full message contained by the `Nestable` and any nested `Throwable`s.

  Parameters:
    `baseMsg` - the base message to use when creating the full message. Should be generally be called via `nestableHelper.getMessage(super.getMessage())`, where `super` is an instance of `Throwable`.
  Returns:
    The concatenated message for this and all nested `Throwable`s
  Since:
    2.0

### getMessages

    public String[] getMessages()

  Returns the error message of this and any nested `Throwable`s in an array of Strings, one element for each message. Any `Throwable` not containing a message is represented in the array by a null. This has the effect of cause the length of the returned array to be equal to the result of the `getThrowableCount()` operation.

  Returns:
    the error messages
  Since:
    2.0

### getThrowable

    public Throwable getThrowable(int index)

  Returns the `Throwable` in the chain of `Throwable`s at the specified index, numbered from 0.

  Parameters:
    `index` - the index, numbered from 0, of the `Throwable` in the chain of `Throwable`s
  Returns:
    the `Throwable`
  Throws:
    `IndexOutOfBoundsException` - if the `index` argument is negative or not less than the count of `Throwable`s in the chain
  Since:
    2.0

### getThrowableCount

    public int getThrowableCount()

  Returns the number of `Throwable`s contained in the `Nestable` contained by this delegate.

  Returns:
    the throwable count
  Since:
    2.0

### getThrowables

    public Throwable[] getThrowables()

  Returns this delegate's `Nestable` and any nested `Throwable`s in an array of `Throwable`s, one element for each `Throwable`.

  Returns:
    the `Throwable`s
  Since:
    2.0

### indexOfThrowable

    public int indexOfThrowable(Class type,
                                int fromIndex)

  Returns the index, numbered from 0, of the first `Throwable` that matches the specified type, or a subclass, in the chain of `Throwable`s with an index greater than or equal to the specified index. The method returns -1 if the specified type is not found in the chain.

  NOTE: From v2.1, we have clarified the `Nestable` interface such that this method matches subclasses. If you want to NOT match subclasses, please use `ExceptionUtils.indexOfThrowable(Throwable, Class, int)` (which is avaiable in all versions of lang). An alternative is to use the public static flag `matchSubclasses` on `NestableDelegate`, however this is not recommended.

  Parameters:
    `type` - the type to find, subclasses match, null returns -1
    `fromIndex` - the index, numbered from 0, of the starting position in the chain to be searched
  Returns:
    index of the first occurrence of the type in the chain, or -1 if the type is not found
  Throws:
    `IndexOutOfBoundsException` - if the `fromIndex` argument is negative or not less than the count of `Throwable`s in the chain
  Since:
    2.0

### printStackTrace

    public void printStackTrace()

  Prints the stack trace of this exception the the standar error stream.

### printStackTrace

    public void printStackTrace(PrintStream out)

  Prints the stack trace of this exception to the specified stream.

  Parameters:
    `out` - `PrintStream` to use for output.
  See Also:
    `printStackTrace(PrintWriter)`

### printStackTrace

    public void printStackTrace(PrintWriter out)

  Prints the stack trace of this exception to the specified writer. If the Throwable class has a `getCause` method (i.e. running on jre1.4 or higher), this method just uses Throwable's printStackTrace() method. Otherwise, generates the stack-trace, by taking into account the 'topDown' and 'trimStackFrames' parameters. The topDown and trimStackFrames are set to 'true' by default (produces jre1.4-like stack trace).

  Parameters:
    `out` - `PrintWriter` to use for output.

### getStackFrames

    protected String[] getStackFrames(Throwable t)

  Captures the stack trace associated with the specified `Throwable` object, decomposing it into a list of stack frames.

  Parameters:
    `t` - The `Throwable`.
  Returns:
    An array of strings describing each stack frame.
  Since:
    2.0

### trimStackFrames

    protected void trimStackFrames(List stacks)

  Trims the stack frames. The first set is left untouched. The rest of the frames are truncated from the bottom by comparing with one just on top.

  Parameters:
    `stacks` - The list containing String[] elements
  Since:
    2.0

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