How can I convert all forms of a specific word in a String to lowercase?-CodePudding

I'm in my first semester in coding and completely stuck on this one.

I want to get all forms of a word (ex: HeLLo, hEllO, heLlo, ...) to change to lowercase and don't know how to get there without writing a condition for every single variation in my file. I have many words I have to convert to either lowercase or uppercase so I realized that there must be a better way of doing but can't figure out which.

Is there a way to get all of these variations at once and convert them to lowercase?

Input = " HeLlo this is my program called HELLO "

Output = " hello this is my program called hello "

I've only tried:

word.replace("HELLO", "hello");

word.replace("Hello", "hello"); and so on..

CodePudding user response：

For a regex solution:

word = word.replaceAll("(?i)hello", "hello");

This is a "case-insensitive" replacement; i.e., all instances of "hello" regardless of case (Hello, HeLlO, HELLO, etc.) will be replaced with "hello".

I found this article to be particularly helpful when learning regex. Here's a live working example.

CodePudding user response：

word.toLowerCase()

or for the opposite

word.toUpperCase()

I hope this helps!

CodePudding user response：

Providing that your input text is the value 'text' (you can make the variable names whatever you want), it should output the correct string. You can add words you want to change to lowercase and uppercase (make sure when you add them they are in lower case)

String text = "Hello I am No GoodBYE";
        String[] lowercase = {"hello", "goodbye"};
        String[] uppercase = {"no", "yes"};
        String[] split_string = text.split(" ");
        for (int i=0;i < split_string.length;i  ){
            for (String low:lowercase){
                if (split_string[i].toLowerCase().equals(low)){
                    split_string[i] = split_string[i].toLowerCase();
                }

        }
            for (String upper:uppercase){
                if (split_string[i].toLowerCase().equals(upper)){
                    split_string[i] = split_string[i].toUpperCase();
                }
            }
    }
        String final_result = "";
        for(String word:split_string){
            final_result = final_result   " "   word;
        }
        System.out.println(final_result);

CodePudding user response：

You can use java.util.regex.Pattern with the CASE_INSENSITIVE Option:

Pattern pattern = Pattern.compile(Pattern.quote("hallo"), Pattern.CASE_INSENSITIVE);
String test = "Hallo FoO HallO BaR HaLLo BAz";  
String replaced = pattern.matcher(test).replaceAll("hallo");
// Output: hallo FoO hallo BaR hallo BAz

CodePudding user response：

Idea:

Change the whole string to lower: HeLlo There heLLO WorlD -> hello there hello world
Look for the index of the target word: indexes of "hello" -> [0, 12]
Change the indexes in the original: hello There hello WorlD

pseudo

String toLower(String input, String replacement) {
     indices = input.toLower().allIndecesOf(replacement)
     result = input.clone()
     for i in indices {
        result = result.replace( i, replacement )
     }
     return result
}