Htykuut

 public String removeStrings()

 {  

    String cleaned = sentence; //sentence and remove are inputs

    int loc = cleaned.indexOf(remove);

    while (loc>-1) //need explanation on how this works

    { 

      cleaned = cleaned.substring(0, loc-1)+cleaned.substring(loc+remove.length());

      loc = cleaned.indexOf(remove);

    }

    return cleaned;

}

Example input sentence="xR-MxR-MHelloxR-M" and remove="R-M" //has to remove x as well in this case
https://github.com/AndrewWeiler/AndrewMac/blob/master/ACSWeiler/src/Lab09/StringRemover.java

String.substring() either returns the part ob a String between two positions (in cleaned.substring(0, 1), that would be the content of cleaned between position 0 and 1) or if you give that method just 1 int-argument, it returns the part of your String, that comes after that position.

For example, with sentence="xR-MxR-MHelloxR-M" and remove="R-M" you would get:

cleaned = "xR-MxR-MHelloxR-M"

loc = 1

So the while-loop would go like this:

cleaned.substring(0, loc-1) returns "x" and cleaned.substring(loc+remove.length()) returns "xR-MHelloxR-M". So cleaned = "xxR-MHelloxR-M". Then, loc becomes the position of the next occurrence of remove.

In words, your while loop removes every occurrence of the String remove out of the String sentence and saves the result in cleaned.

For substring() check https://www.javatpoint.com/substring.

Edit:

If you want the first character before your substring to be removed too, you just need to say

loc = cleaned.indexOf(remove) - 1;