org.jasig.portal.lang
Class ChainedError

java.lang.Object
  java.lang.Throwable
      java.lang.Error
          org.jasig.portal.lang.ChainedError

All Implemented Interfaces:

Serializable, ChainedThrowable

public class ChainedError
extends Error
implements ChainedThrowable

The ChainedError class has facilities for error chaining. Throwables which extend this class inherit these facilities by implementing appropriate constructors.

Version:

"$Revision: 19776 $"

Author:

Jan Nielsen

See Also:

Serialized Form

Constructor Summary

ChainedError()
Constructs an exception with no message and no cause.

ChainedError(String message)
Constructs an exception with a message but no cause.

ChainedError(String message, Throwable cause)
Constructs a new exception instance with a message and a cause.

ChainedError(Throwable cause)
Constructs a new exception instance with no message but a cause.

Method Summary

Throwable	getCause() Returns the cause for this Throwable or null.
String	getLocalizedMessage() Translate the error message to a locale specific error message.
void	printStackTrace() Prints this throwable and its backtrace to the standard error stream.
void	printStackTrace(PrintStream stream) Prints this throwable and its backtrace to the specified print stream.
void	printStackTrace(PrintWriter stream) Prints this throwable and its backtrace to the specified print writer.

Methods inherited from class java.lang.Throwable

fillInStackTrace, getMessage, getStackTrace, initCause, setStackTrace, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ChainedError

public ChainedError()

Constructs an exception with no message and no cause.

ChainedError

public ChainedError(String message)

Constructs an exception with a message but no cause. The message should be an internationalized message.

Parameters:

message - exception message

ChainedError

public ChainedError(Throwable cause)

Constructs a new exception instance with no message but a cause.

Parameters:

cause - underlying cause of the exception

ChainedError

public ChainedError(String message,
                    Throwable cause)

Constructs a new exception instance with a message and a cause. The message should be an internationalized message.

Parameters:

message - exception message

cause - underlying cause of the exception

Method Detail

getCause

public Throwable getCause()

Returns the cause for this Throwable or null. The cause is mean for diagnostic purposes only; Clients should not try to use the cause for additional error handling since that would build an inappropriate subsystem dependency.

Overrides:

getCause in class Throwable

Returns:

throwable associated with this object, or null if not set

getLocalizedMessage

public String getLocalizedMessage()

Translate the error message to a locale specific error message.

Overrides:

getLocalizedMessage in class Throwable

Returns:

localized error message

printStackTrace

public void printStackTrace()

Prints this throwable and its backtrace to the standard error stream. This method prints a stack trace for this Throwable object on the error output stream that is the value of the field System.err. The first line of output contains the result of the Throwable.toString() method for this object. Remaining lines represent data previously recorded by the method Throwable.fillInStackTrace(). The format of this information depends on the implementation, but the following example may be regarded as typical:

 java.lang.NullPointerException
         at MyClass.mash(MyClass.java:9)
         at MyClass.crunch(MyClass.java:6)
         at MyClass.main(MyClass.java:3)
 

This example was produced by running the program:

 class MyClass {
     public static void main(String[] args) {
         crunch(null);
     }
     static void crunch(int[] a) {
         mash(a);
     }
     static void mash(int[] b) {
         System.out.println(b[0]);
     }
 }
 

The backtrace for a throwable with an initialized, non-null cause should generally include the backtrace for the cause. The format of this information depends on the implementation, but the following example may be regarded as typical:

 HighLevelException: MidLevelException: LowLevelException
         at Junk.a(Junk.java:13)
         at Junk.main(Junk.java:4)
 Caused by: MidLevelException: LowLevelException
         at Junk.c(Junk.java:23)
         at Junk.b(Junk.java:17)
         at Junk.a(Junk.java:11)
         ... 1 more
 Caused by: LowLevelException
         at Junk.e(Junk.java:30)
         at Junk.d(Junk.java:27)
         at Junk.c(Junk.java:21)
         ... 3 more
 

Note the presence of lines containing the characters "...". These lines indicate that the remainder of the stack trace for this exception matches the indicated number of frames from the bottom of the stack trace of the exception that was caused by this exception (the "enclosing" exception). This shorthand can greatly reduce the length of the output in the common case where a wrapped exception is thrown from same method as the "causative exception" is caught. The above example was produced by running the program:

 public class Junk {
     public static void main(String args[]) {
         try {
             a();
         } catch(HighLevelException e) {
             e.printStackTrace();
         }
     }
     static void a() throws HighLevelException {
         try {
             b();
         } catch(MidLevelException e) {
             throw new HighLevelException(e);
         }
     }
     static void b() throws MidLevelException {
         c();
     }
     static void c() throws MidLevelException {
         try {
             d();
         } catch(LowLevelException e) {
             throw new MidLevelException(e);
         }
     }
     static void d() throws LowLevelException {
        e();
     }
     static void e() throws LowLevelException {
         throw new LowLevelException();
     }
 }

 class HighLevelException extends Exception {
     HighLevelException(Throwable cause) { super(cause); }
 }

 class MidLevelException extends Exception {
     MidLevelException(Throwable cause)  { super(cause); }
 }

 class LowLevelException extends Exception {
 }
 

Overrides:

printStackTrace in class Throwable

printStackTrace

public void printStackTrace(PrintStream stream)

Prints this throwable and its backtrace to the specified print stream.

Overrides:

printStackTrace in class Throwable

Parameters:

stream - PrintStream to use for output

Throws:

NullPointerException - if stream is null

printStackTrace

public void printStackTrace(PrintWriter stream)

Prints this throwable and its backtrace to the specified print writer.

Overrides:

printStackTrace in class Throwable

Parameters:

stream - PrintWriter to use for output

Throws:

NullPointerException - if stream is null