Programming Tutorials

How to use regionMatches() in Java

By: Mashoud in Java Tutorials on 2007-09-02  

The regionMatches() method in Java is used to check whether the substring of the specified string matches with the substring of another string or not. It has the following two overloaded versions:

1. boolean regionMatches(int toffset, String other, int ooffset, int len): This method compares a substring of the calling string object that begins at the index toffset and has length len with the substring of the other string that begins at index ooffset and has length len. The method returns true if the two substrings match and false otherwise. The comparison is case-sensitive.
2. boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len): This method is similar to the previous one, but it allows the comparison to be case-insensitive if the ignoreCase parameter is set to true.

Here's an example of using the regionMatches() method:

String str1 = "Hello World";
String str2 = "world";
String str3 = "World";
boolean match1 = str1.regionMatches(6, str2, 0, 5); // false
boolean match2 = str1.regionMatches(true, 6, str2, 0, 5); // true
boolean match3 = str1.regionMatches(6, str3, 0, 5); // true
System.out.println(match1);
System.out.println(match2);
System.out.println(match3);

In this example, we have a string str1 and we are comparing its substring "World" starting at index 6 with two other strings str2 and str3. The first comparison is case-sensitive and since the substring of str1 doesn't match with str2, the regionMatches() method returns false. The second comparison is case-insensitive and it returns true because "World" matches with "world". The third comparison is also case-sensitive, but this time it returns true because "World" matches with "World".