User Input as regex not working in JAVA

Question

When I use the following code, it works:

String input = "8:32:03";
String filter = "(\\d{1,2}):(\\d{2})";
Pattern p = Pattern.compile(filter);
Matcher m = p.matcher(input);
if(m.find()) {  //Enters the condition.
    System.out.println("Found => " + m.group() );
}

However, when I try to take user input as regex it does not work?

String input = "8:32:03";
Scanner reader = new Scanner(System.in);
String filter = reader.nextLine();
Pattern p = Pattern.compile(filter);
Matcher m = p.matcher(input);
if(m.find()) {  //Does not enter the condition.
    System.out.println("Found => " + m.group() );
}

I tried using Pattern p = Pattern.compile(Pattern.quote(filter));
But that does not work either.
How can I take user input as a valid regex?

What is your input?

Arcturus
– Arcturus

2017-09-07 10:01:05 +00:00
Commented Sep 7, 2017 at 10:01 — Arcturus
– Arcturus, Commented Sep 7, 2017 at 10:01

Arcturus · Accepted Answer · 2017-09-07 10:02:20Z

2

I am making an assumption here.. Are you inputting (\\d{1,2}):(\\d{2}) ?

If so, the \\ in your example act as escape for the \.. so for your input to be the same, you would need: (\d{1,2}):(\d{2})

answered Sep 7, 2017 at 10:02

Arcturus

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