Pattern Syntax Checker
Method Detail
compile
public static Pattern compile(String regex)
Compiles the given regular expression into a pattern.
Parameters:
regex - The expression to be compiled
Throws:
PatternSyntaxException - If the expression's syntax is invalid
Problem
Using Regex, we can easily match or search for patterns in a text. Before searching for a pattern, we have to specify one using some well-defined syntax.
In this problem, you are given a pattern. You have to check whether the syntax of the given pattern is valid.
Note: In this problem, a regex is only valid if you can compile it using the Pattern.compile method.
Input Style
The first line of input contains an integer N , denoting the number of test cases. The next N lines contain a string of any printable characters representing the pattern of a regex.
Output Format
For each test case, print Valid if the syntax of the given pattern is correct. Otherwise, print Invalid. Do not print the quotes.
Sample Input
3
([A-Z])(.+)
[AZ[a-z](a-z)
batcatpat(nat
Sample Output
Valid
Invalid
Invalid
Recommended: Please try your approach on your integrated development environment (IDE) first, before moving on to the solution.
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Solution
( java )
import java.util.Scanner;
import java.util.regex.*;
public class Solution
{
public static void main(String[] args){
Scanner in = new Scanner(System.in);
int testCases =Integer.parseInt(in.nextLine());
while(testCases>0){
String pattern = in.nextLine();
try{
Pattern.compile(pattern);
System.out.println("Valid");
}
catch(PatternSyntaxException e){
System.out.println("Invalid");
}
testCases--;
}
}
}
