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Introduction
The java.util.regex.PatternSyntaxException class represents a unchecked exception thrown to indicate a syntax error in a regular-expression pattern.
Class declaration
Following is the declaration for java.util.regex.PatternSyntaxException class −
public class PatternSyntaxException extends IllegalArgumentException
Constructors
| Sr.No | Method & Description |
|---|---|
| 1 | PatternSyntaxException(String desc, String regex, int index)
Constructs a new instance of this class. |
Class methods
| Sr.No | Method & Description |
|---|---|
| 1 | String getDescription()
Retrieves the description of the error. |
| 2 | int getIndex()
Retrieves the error index. |
| 3 | 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. |
| 4 | String getPattern()
Retrieves the erroneous regular-expression pattern. |
Methods inherited
This class inherits methods from the following classes −
- Java.lang.Throwable
- Java.lang.Object
Example
The following example shows the usage of java.util.regex.Pattern.PatternSyntaxException class methods.
package com.tutorialspoint;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
public class PatternSyntaxExceptionDemo {
private static String REGEX = "[";
private static String INPUT = "The dog says meow " + "All dogs say meow.";
private static String REPLACE = "cat";
public static void main(String[] args) {
try{
Pattern pattern = Pattern.compile(REGEX);
// get a matcher object
Matcher matcher = pattern.matcher(INPUT);
INPUT = matcher.replaceAll(REPLACE);
} catch(PatternSyntaxException e){
System.out.println("PatternSyntaxException: ");
System.out.println("Description: "+ e.getDescription());
System.out.println("Index: "+ e.getIndex());
System.out.println("Message: "+ e.getMessage());
System.out.println("Pattern: "+ e.getPattern());
}
}
}
Let us compile and run the above program, this will produce the following result −
PatternSyntaxException: Description: Unclosed character class Index: 0 Message: Unclosed character class near index 0 [ ^ Pattern: [
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