practice: removing all string occurrences from another

Question

I'm doing some beginner's coding practice and I ran into this problem:Given two strings, base and remove, return a version of the base string where all instances of the remove string have been removed. (not case sensitive).

This is what I have so far, but it's not working at all.

public String withoutString(String base, String remove) {

 for (int i=0; i<base.length()-remove.length(); i++){
  if (base.substring(i, i+remove.length()).equals(remove)){
  base = base.substring(i, base.indexOf("remove")-1) + base.substring(base.indexOf("remove"), base.length()-remove.length());
    }
  }
  return base;
}

I've yet to deal with the case sensitive part to make it more visible for myself. I'm also not sure why I can't use base.replaceAll("remove",""); Any help is appreciated.

EDIT*: I made a rookie mistake and the replaceAll still works. Additionally, how could I have done this using loops and conditionals? Would it have been messy like what I had previously?

Answer 1

You can use

String result = base.replaceAll(remove,"");

With quotes as you where trying it is actually trying to remove the string "remove" .

To deal with the case insenstive you can use the regex flag for ignore case (?i) in the front so then you can call

String result = base.replaceAll("(?i)" + remove,"");

This does mean that the String remove, is now a regular expression now so special characters may have undesired results. For example if your remove string was . , you would end up with every character removed. If you don't want it as a regex then use

String result =  Pattern.compile(remove, Pattern.LITERAL).matcher(base).replaceAll("")

Which can also include the case insensitive flag like so as they are a bitmask, see Pattern for more

Pattern.LITERAL | Pattern.CASE_INSENSITIVE

EDIT

To do it using your loop, just do this loop

for (int i=0; i <= base.length()-remove.length(); i++)
{
    if (base.substring(i, i+remove.length()).equals(remove))
    {  
        base = base.substring(0, i) + base.substring(i + remove.length() , base.length());
        i--;
    }
}

Answer 2

indexOf("remove") means, you are searching for the (fixed) STRING remove , not for the value of the String named remove - which is most likey not, what you want to do. Same applies for your replaceAll("remove") attempt.

remove the " so you are using the VALUE of the String named remove , not the fixed string "remove"

Example:

String remove = "test";
System.out.println(remove) // will print: test
System.out.println("remove") // will print: remove

Answer 3

你应该使用(?i)标志或：

base = Pattern.compile(remove, Pattern.CASE_INSENSITIVE).matcher(base).replaceAll("");

Answer 4

Try this :

if(base.indexOf(remove) != -1){
base.replaceAll(remove,"");
}