Best way to implement while loop in java 8 or later

Question

I have to remove all slash (/) from the beginning of string. So I have written

while (convertedUrl.startsWith("\\")) 
{
     convertedUrl = convertedUrl.substring(1);
}

Above code creates string for each substring. Is there any better way to write this code in java 8 or later? How can I do it keeping mind memory utilisation and performance.

Check this similar post... stackoverflow.com/questions/28741673/… — Reeta Wani
– Reeta Wani, Commented Apr 8, 2020 at 14:09
Your code handles \ but in your question you claim you want to remove / so which is it? — Pshemo
– Pshemo, Commented Apr 8, 2020 at 14:11
Anyway what is the exact text you are handling and what you want to achieve? If it is some common task maybe using URI/URL classes would be easier? — Pshemo
– Pshemo, Commented Apr 8, 2020 at 14:13
Aside from that you could use regex like convertedUrl = convertedUrl.replaceFirst("^\\\\+", ""); (if you want to remove series of \ at beginning of string). Change \\\\ to / if you want to remove /. — Pshemo
– Pshemo, Commented Apr 8, 2020 at 14:17
Keep in mind that you only need to optimize this for performance if you measure your program's performance and this is the bottleneck — lucidbrot
– lucidbrot, Commented Apr 8, 2020 at 14:26

Oleg · Accepted Answer · 2020-04-08 14:30:12Z

4

I would guess at:

 int len = str.length();
 int i=0;
 for (; i<len && str.charAt(i) == '\\'; ++i) {
      ;
 }
 return str.substring(i);

I write str instead of convertedUrl because this should be in its own method.

It is unlikely this is a performance bottleneck, but the original code may run as slow as O(n^2) (depending on implementation).

edited Apr 8, 2020 at 14:30

Oleg

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answered Apr 8, 2020 at 14:11

Tom Hawtin - tackline

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Comments

TechSavvy · Accepted Answer · 2020-04-08 14:22:03Z

-1

can you simply not use something like this, to replace all the "/" in one go

convertedUrl = convertedUrl.replaceAll("\\/","");

I am sorry for the initial one, but I think this will do:

convertedUrl = convertedUrl.replaceFirst("^/*","");

OR this:

convertedUrl = convertedUrl.replaceAll("^/*","");

both will get the job done! as they replaces all the leading "/" chars!

edited Apr 8, 2020 at 14:22

answered Apr 8, 2020 at 14:15

TechSavvy

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2 Comments

Pshemo Over a year ago

That would replace all / in string. Not what OP wants (at least according to his code).

Pshemo Over a year ago

Also you don't need to escape / in Java regex since it doesn't use /regex/flags syntaks which makes / special, but plain regex where / doesn't have any special meaning.

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