java - Regex not valid when trying to invalidate alpha's and non-zeros -

java - Regex not valid when trying to invalidate alpha's and non-zeros -

wrote method takes in string , checks see follow conditions:

if string "quit", terminate program. if string value other integer, should homecoming "invalid input ". any negative integers , 0 should homecoming "invalid input".

however, when passed in 10, returned "invalid input"?

please advise:

public static string validate(string input) { pattern pattern = pattern.compile(".*[^1-9].*"); stringbuilder results = new stringbuilder(); if (input.equals("quit")) { system.exit(1); } else if (!pattern.matcher(input).matches() == false) { results.append("invalid input "); results.append("'"); results.append(input); results.append("'"); } homecoming results.tostring(); }

what's wrong doing?

you should write pattern of expect instead of you're not. describe want simpler describe rest of it.

so expect :

pattern acceptpattern = pattern.compile("[1-9][0-9]*");

you may consider create conditional look simpler , right not using both ! , == false @ same time:

which create :

if (!acceptpattern .matcher(input).matches()) {//invalid input code}

or

if (acceptpattern .matcher(input).matches() == false) {//invalid input code}

note :

you write if(!a == false) => if(a == true) => if(a) inverse

java regex