How to find if a Java String contains X or Y and contains Z

Question

I\'m pretty sure regular expressions are the way to go, but my head hurts whenever I try to work out the specific regular expression.

What regular expression do I ne

Answer 1

If you're not 100% comfortable with regular expressions, don't try to use them for something like this. Just do this instead:

string s = test_string.toLowerCase();
if (s.contains("parsing") && (s.contains("error") || s.contains("warning")) {
    ....

because when you come back to your code in six months time you'll understand it at a glance.

Edit: Here's a regular expression to do it:

(?i)(?=.*parsing)(.*(error|warning).*)

but it's rather inefficient. For cases where you have an OR condition, a hybrid approach where you search for several simple regular expressions and combine the results programmatically with Java is usually best, both in terms of readability and efficiency.

Answer 2

try:

 If((str.indexOf("WARNING") > -1 || str.indexOf("ERROR") > -1) && str.indexOf("parsin") > -1)

Answer 3

I usually use this applet to experiment with reg. ex. The expression may look like this:

if (str.matches("(?i)^.*?(WARNING|ERROR).*?parsing.*$")) {
...

But as stated in above answers it's better to not use reg. ex. here.

Answer 4

If you've a variable number of words that you want to match I would do something like that:

String mystring = "Text I want to match";
String[] matchings = {"warning", "error", "parse", ....}
int matches = 0;
for (int i = 0; i < matchings.length(); i++) {
  if (mystring.contains(matchings[i]) {
    matches++;
  }
}

if (matches == matchings.length) {
   System.out.println("All Matches found");
} else {
   System.out.println("Some word is not matching :(");
}

Note: I haven't compiled this code, so could contain typos.

Answer 5

With multiple .* constucts the parser will invoke thousands of "back off and retry" trial matches.

Never use .* at the beginning or in the middle of a RegEx pattern.

Answer 6

Regular Expressions are not needed here. Try this:

if((string1.toUpperCase().indexOf("ERROR",0) >= 0 ||  
  string1.toUpperCase().indexOf("WARNING",0) >= 0 ) &&
  string1.toUpperCase().indexOf("PARSING",0) >= 0 )

This also takes care of the case-insensitive criteria