org.apache.hadoop.chukwa.util

Class RegexUtil.CheckedPatternSyntaxException

java.lang.Object

java.lang.Throwable

java.lang.Exception

org.apache.hadoop.chukwa.util.RegexUtil.CheckedPatternSyntaxException

All Implemented Interfaces:

Serializable

Enclosing class:

RegexUtil

public static class RegexUtil.CheckedPatternSyntaxException
extends Exception

A checked version of PatternSyntaxException.

This exception is useful when an illegal regex is detected but the contextual information to report a helpful error message is not available at the current depth in the call stack. By using a checked PatternSyntaxException the error must be handled up the call stack where a better error message can be reported.

Typical usage is:

 void myMethod(...) throws CheckedPatternSyntaxException {
   ...
   if (! isRegex(myString)) {
     throw new CheckedPatternSyntaxException(...);
   }
   ... Pattern.compile(myString) ...
 

Simply calling Pattern.compile would have a similar effect, in that PatternSyntaxException would be thrown at run time if myString is not a regular expression. There are two problems with such an approach. First, a client of myMethod might forget to handle the exception, since PatternSyntaxException is not checked. Also, the Regex Checker would issue a warning about the call to Pattern.compile that might throw an exception. The above usage pattern avoids both problems.

See Also:

PatternSyntaxException, Serialized Form

Constructor Summary

Constructors

Constructor and Description
CheckedPatternSyntaxException(PatternSyntaxException pse) Constructs a new CheckedPatternSyntaxException equivalent to the given PatternSyntaxException.
CheckedPatternSyntaxException(String desc, String regex, int index) Constructs a new CheckedPatternSyntaxException.

Method Summary

Modifier and Type	Method and Description
String	getDescription() Retrieves the description of the error.
int	getIndex() Retrieves the error index.
String	getMessage() Returns a multi-line string containing the description of the syntax error and its index, the erroneous regular-expression pattern, and a visual indication of the error index within the pattern.
String	getPattern() Retrieves the erroneous regular-expression pattern.

Methods inherited from class java.lang.Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CheckedPatternSyntaxException

public CheckedPatternSyntaxException(PatternSyntaxException pse)

Constructs a new CheckedPatternSyntaxException equivalent to the given PatternSyntaxException.

Consider calling this constructor with the result of RegexUtil.regexError(java.lang.String).

Parameters:

pse - is PatternSyntaxException object

CheckedPatternSyntaxException

public CheckedPatternSyntaxException(String desc,
                                     String regex,
                                     int index)

Constructs a new CheckedPatternSyntaxException.

Parameters:

desc - A description of the error

regex - The erroneous pattern

index - The approximate index in the pattern of the error, or -1 if the index is not known

Method Detail

getDescription

public String getDescription()

Retrieves the description of the error.

Returns:

The description of the error

getIndex

public int getIndex()

Retrieves the error index.

Returns:

The approximate index in the pattern of the error, or -1 if the index is not known

getMessage

public String getMessage()

Returns a multi-line string containing the description of the syntax error and its index, the erroneous regular-expression pattern, and a visual indication of the error index within the pattern.

Overrides:

getMessage in class Throwable

Returns:

The full detail message

getPattern

public String getPattern()

Retrieves the erroneous regular-expression pattern.

Returns:

The erroneous pattern