Equals VS indexOf

[Jordan Smith]

Hi!
I want to check if "News" appears in a string
what is being calculated quicker?

  String theString="www.mysite.com/News";
boolean isEqaul = theString.equals("www.mysite.com/News");

  

or

String theString="www.mysite.com/News";
boolean isEqaul = theString.indexOf("News")!=-1;

    

[Paul Sturrock]

If your requirement is to find out if a pattern appears in a String you can't use equals. This will only match if the whole String is equal to your test.

[Jordan Smith]

right.
this is why my condition is different in each case
actually the string for sure will start with www.mysite.com/ and the question is about the word News.

I thought to write endsWith instead of equals. but still, what is quicker? endsWith or indexOf?

[Henry Wong]

I don't think this will make a notable difference, as you application will do something else after it validates the URL. However, if you really are concerned, then you can write a test -- and test both options.

Henry

[Sean Clark]

Hey,

I don't think it will make a lot of of difference, you could also use the matches method, I prefer using this as it allows you to add a REGEX which is I think is more powerful. so...

String url = "www.mysite.com/News";
url.matches("News"); // true
url.matches("News$"); // true as long as news is at the end of the String

Also indexOf() only searches for a character so would be no use for you.
Ends with would also work so long as you weren't going to be adding any GET parameters on the end of your URL.
You could also use .contains("News");

You have a load of choices!

Sean

[Ireneusz Kordal]

odelya yomtov-glick wrote:what is quicker? endsWith or indexOf?

endsWith is absolutely quicker.
But you wrote

I want to check if "News" appears in a string

in this case endWith wont work, because it cheks if the string ENDS with given substring,
but not if the substring appears somewhere in the string - you must use indexOf to check it.

[Rob Spoor]

I agree with Ireneusz that endsWith, startsWith and equals are most likely faster than indexOf.

In those 3 methods, the start position is known, so you need only one loop: over the string to check for. With indexOf, you will need to loop over the string to search in, checking each time if the string to search for is located at that position. I've confirmed this by checking String.java - equals, startsWith and endsWith only have one single loop whereas indexOf has a loop in a loop.

[R van Vliet]

You could, ofcourse, test it

[Joanne Neal]

Sean Clark wrote:Also indexOf() only searches for a character so would be no use for you.

Unless you use the version of indexOf that searches for a String

[Sean Clark]

Joanne Neal wrote:

Sean Clark wrote:Also indexOf() only searches for a character so would be no use for you.

Unless you use the version of indexOf that searches for a String

Good point, I'm not sure how I missed that.
I have a lot to learn!

[Anjali Raman]

Hi,
You could use the contains() method too. Its pretty fast.

Cheers
Anjali

[D. Ogranos]

Sean Clark wrote:Hey,

I don't think it will make a lot of of difference, you could also use the matches method, I prefer using this as it allows you to add a REGEX which is I think is more powerful. so...

Since the OP asked about the quickest way, I wouldn't recommend using regular expressions. They are a LOT slower than using indexOf().

That said, I ran two quick tests. I found that equals() is about 6-7 times faster than indexOf() (rather, I compared the the expressions equals(x) and indexOf(x) != -1). However, endsWith() is only slightly faster than indexOf(), which in turn is slightly faster than contains(). A test of matches() vs. indexOf() showed that indexOf() was about 33 times faster than matches(). Of course, all these tests are simple and with short example strings only.

[Sean Clark]

I wouldn't recommend using regular expressions. They are a LOT slower than using indexOf().

I agree... Regexs have their place, but not here.

apparently equals() and contains() are about the same speed.