Android Method TextUtils.regionMatches

Question

I has found this android method TextUtils.regionMatches

But for some reason, so it is not clear how this function works.

The function can be found here: http://developer.android.com/reference/android/text/TextUtils.html#regionMatches%28java.lang.CharSequence,%20int,%20java.lang.CharSequence,%20int,%20int%29

And the base code for this method here, http://androidxref.com/4.1.1/xref/frameworks/base/core/java/android/text/TextUtils.java#220

Thanks for those who might shed some light on how the function is called.

Answer 1

public static boolean regionMatches (CharSequence one,
                   int toffset, CharSequence two, int ooffset, int len)

Sample code:

CharSequence one = "asdfQWERTYc1234";
CharSequence two = "ghjklzxcQWERTYg7890kl";
boolean match = TextUtils.regionMatches(one, 4, two, 8, 6);

match is true.

Explanation:

In charsequence one, start from toffset (4) and get a number of characters equal to len (6) => QWERTY

In charsequence two, start from ooffset (8) and get a number of characters equal to len (6) => QWERTY

Both charsequences match, so the method returns true.

Answer 2

I just wrote this to check for "http" at the very first of a string and another example always helps visitors.

url = "url.without/protocol.info"; // will match
// url = "http://url.with/protocol.info"; // won't match

String match = "http";
if(!url.regionMatches(true, 0, match, 0, match.length())) {
    //do something
}