Java - Ignore case checking user input

Question

I need to check if the user input matches anything in a Set or List, but I am currently using .contains(). Obviously this is not working when the user inputs something that is not the correct case, so I was thinking of using .matches( regex ), but am not a professional regexer.

Would could I use Regex or Pattern to check if the user input matches anything in a List, case aside.

Thank you.

I did just notice that I will have to use a for-loop to get the elements out of my Set before comparing them with .matches().

Solution 1

You can temporarily convert both strings into lowercase or both into uppercase and then do the matching.

for(int i=0;i<myList.length-1;i++){
       if(myString.toLowerCase().contains(myList.get(i).toLowerCase())){
           // your code if myString is contained within a String in the List
       }
}

or

for(int i=0;i<myList.length-1;i++){
       if(myString.toUpperCase().contains(myList.get(i).toUpperCase())){
           // your code if myString is contained within a String in the List
       }
}

Solution 2

You can try Pattern.CASE_INSENSITIVE with the Pattern.

Solution 3

I don't understand why you can't use String.equalsIgnoreCase(). Regex is not needed for this. If you use a List, you can use .stream().anyMatch() with this Predicate:

c -> c.equalsIgnoreCase(data)

Code Sample:

public static void main(String[] args) throws Exception {
    List<String> check = new ArrayList() {{
        add("dog");  
        add("CAT");
        add("oWl");
        add("GiraFFe");
    }};

    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter data: ");
    String data = scanner.nextLine();

    if (check.stream().anyMatch(c -> c.equalsIgnoreCase(data))) {
        System.out.println("Data found");
    } else {
        System.out.println("Data not found");
    }
}

Results:

Enter data: gIRAffE
Data found

Enter data: lamb
Data not found

Comments

[Shar1er80]

Why bother upper/lower casing when you can just use String.equalsIgnoreCase()?

[RoHaN]

String.equalsIgnoreCase() checks whether that it is that actual string not more not less. we need contains to check whether that it contains the string not equals to the exact string.

[David Veszelovszki]

String.equalsIgnoreCase() checks whether that it is the full string. OP needs contains() to check if it contains the string, not equals to it.