Option to ignore case with .contains method?

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Is there an option to ignore case with .contains() method?

I have an ArrayList of DVD object. Each DVD object has a few elements, one of them is a title. And I have a method that searches for a specific title. It works, but I'd like it to be case insensitive.


I'm guessing you mean ignoring case when searching in a string?

I don't know any, but you could try to convert the string to search into either to lower or to upper case, then search.

// s is the String to search into, and seq the sequence you are searching for.
bool doesContain = s.toLowerCase().contains(seq);

Edit: As Ryan Schipper suggested, you can also (and probably would be better off) do seq.toLowerCase(), depending on your situation.

Case-Insensitive String Matching in Java, Learn how to perform case-insensitive String matching in Java. this case, we'll transform both strings to lowercase and then use the contains() method: Another option is by using String.matches() with regular expressions:. It looks more elegant then converting the whole string to lower case and it may be more efficient. With toLowerCase() the code have two pass over the string, one pass is on the entire string to convert it to lower case and another is to look for the desired index.


If you're using Java 8

List<String> list = new ArrayList<>();

boolean containsSearchStr = list.stream().anyMatch("search_value"::equalsIgnoreCase);

Java String equals() and equalsIgnoreCase() Methods example, In this tutorial we will discuss equals() and equalsIgnoreCase() methods. Both of these methods are used for comparing two strings. The only difference between  If you stumbled upon this post it probably means that you’re trying to use the String. Contains method in a C# application in a case-insensitive way: as a matter of fact, there isn’t a built-in overload method accepting a StringComparison options object, hence is not possible to do that.


private boolean containsIgnoreCase(List<String> list, String soughtFor) {
    for (String current : list) {
        if (current.equalsIgnoreCase(soughtFor)) {
            return true;
        }
    }
    return false;
}

localizedCaseInsensitiveContains(_:), Returns a Boolean value indicating whether the string contains a given string by performing a case-insensitive, locale-aware search. Availability. iOS 8.0+  The string.Contains() method in C# is case sensitive. And there is not StringComparison parameter available similar to Equals() method, which helps to compare case insensitive. If you run the following tests, TestStringContains2() will fail.


This probably isn't the best way for your particular problem, but you can use the String.matches(String regex) method or the matcher equivalent. We just need to construct a regular expression from your prospective title. Here it gets complex.

List<DVD> matchingDvds(String titleFragment) {
    String escapedFragment = Pattern.quote(titleFragment);
    // The pattern may have contained an asterisk, dollar sign, etc.
    // For example, M*A*S*H, directed by Robert Altman.
    Pattern pat = Pattern.compile(escapedFragment, Pattern.CASE_INSENSITIVE);
    List<DVD> foundDvds = new ArrayList<>();
    for (DVD dvd: catalog) {
        Matcher m = pat.matcher(dvd.getTitle());
        if (m.find()) {
            foundDvds.add(dvd);
        }
    }
    return foundDvds;
}

But this is inefficient, and it's being done purely in Java. You would do better to try one of these techniques:

  1. Learn the Collator and CollationKey classes.
  2. If you have no choice but to stay in the Java world, add a method to DVD, boolean matches(String fragment). Have the DVD tell you what it matches.
  3. Use a database. If it supports case-insensitive collations, declare the title column of the DVD table that way. Use JDBC or Hibernate or JPA or Spring Data, whichever you choose.
  4. If the database supports advanced text search, like Oracle, use that.
  5. Back in the Java world, use Apache Lucene and possibly Apache Solr.
  6. Use a language tuned for case-insensitive matches.

If you can wait until Java 8, use lambda expressions. You can avoid the Pattern and Matcher class that I used above by building the regex this way:

   String escapedFragment = Pattern.quote(titleFragment);
   String fragmentAnywhereInString = ".*" + escapedFragment + ".*";
   String caseInsensitiveFragment = "(?i)" + fragmentAnywhereInString;
   // and in the loop, use:
   if(dvd.getTitle().matches(caseInsensitiveFragment)) {
        foundDvds.add(dvd);
    }

But this compiles the pattern too many times. What about lower-casing everything?

if (dvd.getTitle().toLowerCase().contains(titleFragment.toLowerCase()))

Congratulations; you've just discovered the Turkish problem. Unless you state the locale in toLowerCase, Java finds the current locale. And the lower-casing is slow because it has to take into account the Turkish dotless i and dotted I. At least you have no patterns and no matchers.

Java: How to perform a case-insensitive search using the String , syntax to make your search case-insensitive. (Also, remember that when you use the matches method, your regex pattern must match the entire  str.contains(null); Java String contains() method Example. The second print statement displayed false because the contains() method is case sensitive. You can also use the contains() method for case insensitive check, I have covered this at the end of this tutorial.


In Java 8 you can use the Stream interface:

return dvdList.stream().anyMatch(d -> d.getTitle().equalsIgnoreCase("SomeTitle"));

Match regular expression (case insensitive), This MATLAB function returns the starting index of each substring of str that To disable case-sensitive matching for regexp , use the 'ignorecase' option. Each expression can contain characters, metacharacters, operators, tokens, and flags​  Another option is to use String#regionMatches() method, which takes a boolean argument stating whether to do case-sensitive matching or not. You can use it like this: String haystack = "Session"; String needle = "sEsSi"; System.out.println(haystack.regionMatches(true, 0, needle, 0, 5)); // true


Is there case-insensitive option for "-replace" and "[contains , Use the Replace() method of a string object. $_.'#text'.Replace('text','fool'). It's case-sensitive already. You aren't using the -contains operator; I'm not familiar  pandas.Series.str.contains¶ Series.str.contains (self, pat, case = True, flags = 0, na = nan, regex = True) [source] ¶ Test if pattern or regex is contained within a string of a Series or Index. Return boolean Series or Index based on whether a given pattern or regex is contained within a string of a Series or Index. Parameters pat str


pandas.Series.str.contains, If True, case sensitive. flags : int, default 0 (no flags). Flags to pass through to the re module, e.g. re.IGNORECASE. na : default NaN. Fill value for missing values. This method compares this String to another String, ignoring case considerations. Two strings are considered equal ignoring case, if they are of the same length, and corresponding characters in the two strings are equal ignoring case. Syntax. Here is the syntax of this method − public boolean equalsIgnoreCase(String anotherString) Parameters


ArrayList contains case sensitivity, Option to ignore case with .contains method?, List<String> list = new ArrayList<>(​); boolean containsSearchStr = list.stream(). Use a language tuned for  .NET Framework only: To determine whether a string contains a specified substring by using something other than ordinal comparison (such as culture-sensitive comparison, or ordinal case-insensitive comparison), you can create a custom method. The following example illustrates one such approach.