Class ExceptionUtils


  • public class ExceptionUtils
    extends java.lang.Object

    ExceptionUtils provides utilities for manipulating Throwable objects.

    Since:
    1.0
    Author:
    Daniel Rall, Dmitri Plotnikov, Stephen Colebourne
    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected static java.lang.String[] CAUSE_METHOD_NAMES
      The names of methods commonly used to access a wrapped exception.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected ExceptionUtils()
      Constructs a new ExceptionUtils.
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static void addCauseMethodName​(java.lang.String methodName)
      Adds to the list of method names used in the search for Throwable objects.
      static java.lang.Throwable getCause​(java.lang.Throwable throwable)
      Introspects the specified Throwable to obtain the cause.
      static java.lang.Throwable getCause​(java.lang.Throwable throwable, java.lang.String[] methodNames)
      Introspects the specified Throwable to obtain the cause using a supplied array of method names.
      static java.lang.String getFullStackTrace​(java.lang.Throwable t)
      A way to get the entire nested stack-trace of an throwable.
      static java.lang.Throwable getRootCause​(java.lang.Throwable throwable)
      Walks through the exception chain to the last element -- the "root" of the tree -- using getCause(Throwable), and returns that exception.
      static java.lang.String[] getRootCauseStackTrace​(java.lang.Throwable t)
      Creates a compact stack trace for the root cause of the supplied throwable.
      static java.lang.String[] getStackFrames​(java.lang.Throwable t)
      Captures the stack trace associated with the specified Throwable object, decomposing it into a list of stack frames.
      static java.lang.String getStackTrace​(java.lang.Throwable t)
      A convenient way of extracting the stack trace from an exception.
      static int getThrowableCount​(java.lang.Throwable throwable)
      Returns the number of Throwable objects in the exception chain.
      static java.lang.Throwable[] getThrowables​(java.lang.Throwable throwable)
      Returns the list of Throwable objects in the exception chain.
      static int indexOfThrowable​(java.lang.Throwable throwable, java.lang.Class type)
      Delegates to indexOfThrowable(Throwable, Class, int), starting the search at the beginning of the exception chain.
      static int indexOfThrowable​(java.lang.Throwable throwable, java.lang.Class type, int fromIndex)
      Returns the (zero based) index, of the first Throwable that matches the specified type in the exception chain of Throwable objects with an index greater than or equal to the specified index, or -1 if the type is not found.
      static boolean isNestedThrowable​(java.lang.Throwable throwable)
      Whether an Throwable is considered nested or not.
      static void printRootCauseStackTrace​(java.lang.Throwable t)
      Equivalent to printRootCauseStackTrace(t, System.err)
      static void printRootCauseStackTrace​(java.lang.Throwable t, java.io.PrintStream stream)
      Prints a compact stack trace for the root cause of a throwable.
      static void printRootCauseStackTrace​(java.lang.Throwable t, java.io.PrintWriter writer)
      Same as printRootCauseStackTrace(t, stream), except it takes a PrintWriter as an argument.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • CAUSE_METHOD_NAMES

        protected static java.lang.String[] CAUSE_METHOD_NAMES
        The names of methods commonly used to access a wrapped exception.
    • Constructor Detail

      • ExceptionUtils

        protected ExceptionUtils()
        Constructs a new ExceptionUtils. Protected to discourage instantiation.
    • Method Detail

      • addCauseMethodName

        public static void addCauseMethodName​(java.lang.String methodName)

        Adds to the list of method names used in the search for Throwable objects.

        Parameters:
        methodName - the methodName to add to the list, null and empty strings are ignored
      • getCause

        public static java.lang.Throwable getCause​(java.lang.Throwable throwable)

        Introspects the specified Throwable to obtain the cause.

        The method searches for methods with specific names that return a Throwable object. This will pick up most wrapping exceptions, including those from JDK 1.4, and The method names can be added to using addCauseMethodName(String). The default list searched for are:

        • getCause()
        • getNextException()
        • getTargetException()
        • getException()
        • getSourceException()
        • getRootCause()
        • getCausedByException()
        • getNested()

        In the absence of any such method, the object is inspected for a detail field assignable to a Throwable.

        If none of the above is found, returns null.

        Parameters:
        throwable - The exception to introspect for a cause.
        Returns:
        The cause of the Throwable.
        Throws:
        java.lang.NullPointerException - if the throwable is null
      • getCause

        public static java.lang.Throwable getCause​(java.lang.Throwable throwable,
                                                   java.lang.String[] methodNames)

        Introspects the specified Throwable to obtain the cause using a supplied array of method names.

        Parameters:
        throwable - The exception to introspect for a cause.
        methodNames - the methods names to match
        Returns:
        The cause of the Throwable.
        Throws:
        java.lang.NullPointerException - if the method names array is null or contains null
        java.lang.NullPointerException - if the throwable is null
      • getRootCause

        public static java.lang.Throwable getRootCause​(java.lang.Throwable throwable)

        Walks through the exception chain to the last element -- the "root" of the tree -- using getCause(Throwable), and returns that exception.

        Parameters:
        throwable - the throwable to get the root cause for
        Returns:
        The root cause of the Throwable.
      • getThrowableCount

        public static int getThrowableCount​(java.lang.Throwable throwable)

        Returns the number of Throwable objects in the exception chain.

        Parameters:
        throwable - the exception to inspect
        Returns:
        The throwable count.
      • getThrowables

        public static java.lang.Throwable[] getThrowables​(java.lang.Throwable throwable)

        Returns the list of Throwable objects in the exception chain.

        Parameters:
        throwable - the exception to inspect
        Returns:
        The list of Throwable objects.
      • indexOfThrowable

        public static int indexOfThrowable​(java.lang.Throwable throwable,
                                           java.lang.Class type)

        Delegates to indexOfThrowable(Throwable, Class, int), starting the search at the beginning of the exception chain.

        Parameters:
        throwable - the exception to inspect
        type - Class to look for
        Returns:
        index of the stack matching the type
        See Also:
        indexOfThrowable(Throwable, Class, int)
      • indexOfThrowable

        public static int indexOfThrowable​(java.lang.Throwable throwable,
                                           java.lang.Class type,
                                           int fromIndex)

        Returns the (zero based) index, of the first Throwable that matches the specified type in the exception chain of Throwable objects with an index greater than or equal to the specified index, or -1 if the type is not found.

        Parameters:
        throwable - the exception to inspect
        type - Class to look for
        fromIndex - the (zero based) index of the starting position in the chain to be searched
        Returns:
        the first occurrence of the type in the chain, or -1 if the type is not found
        Throws:
        java.lang.IndexOutOfBoundsException - If the fromIndex argument is negative or not less than the count of Throwables in the chain.
      • printRootCauseStackTrace

        public static void printRootCauseStackTrace​(java.lang.Throwable t,
                                                    java.io.PrintStream stream)
        Prints a compact stack trace for the root cause of a throwable. The compact stack trace starts with the root cause and prints stack frames up to the place where it was caught and wrapped. Then it prints the wrapped exception and continues with stack frames until the wrapper exception is caught and wrapped again, etc.

        The method is equivalent to t.printStackTrace() for throwables that don't have nested causes.

        Parameters:
        t - the exception
        stream - the stream
      • printRootCauseStackTrace

        public static void printRootCauseStackTrace​(java.lang.Throwable t)
        Equivalent to printRootCauseStackTrace(t, System.err)
        Parameters:
        t - the exception
      • printRootCauseStackTrace

        public static void printRootCauseStackTrace​(java.lang.Throwable t,
                                                    java.io.PrintWriter writer)
        Same as printRootCauseStackTrace(t, stream), except it takes a PrintWriter as an argument.
        Parameters:
        t - the cause
        writer - the writer
      • getRootCauseStackTrace

        public static java.lang.String[] getRootCauseStackTrace​(java.lang.Throwable t)
        Creates a compact stack trace for the root cause of the supplied throwable. See printRootCauseStackTrace(Throwable t, PrintStream s)
        Parameters:
        t - the cause
        Returns:
        the Stack
      • getStackTrace

        public static java.lang.String getStackTrace​(java.lang.Throwable t)
        A convenient way of extracting the stack trace from an exception.
        Parameters:
        t - The Throwable.
        Returns:
        The stack trace as generated by the exception's printStackTrace(PrintWriter) method.
      • getFullStackTrace

        public static java.lang.String getFullStackTrace​(java.lang.Throwable t)
        A way to get the entire nested stack-trace of an throwable.
        Parameters:
        t - The Throwable.
        Returns:
        The nested stack trace, with the root cause first.
      • isNestedThrowable

        public static boolean isNestedThrowable​(java.lang.Throwable throwable)
        Whether an Throwable is considered nested or not.
        Parameters:
        throwable - The Throwable.
        Returns:
        boolean true/false
      • getStackFrames

        public static java.lang.String[] getStackFrames​(java.lang.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.