FULL PRODUCT VERSION :
java version  " 1.7.0_25 " 
Java(TM) SE Runtime Environment (build 1.7.0_25-b15)
Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
3.8.0-25-generic #37-Ubuntu SMP Thu Jun 6 20:47:07 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
The problem does not happen when the test is run in Turkish locale.
In order to reproduce the problem, the locale should be set to English (or probably any non-Turkish locale)

In English locale, if a string with dotted-capital-I (Turkish-I, \u0130) character is converted to lower case, using toLoweCase method, an extra (and invalid) character is added to the resulting string just after the Turkish-I character.


REGRESSION.  Last worked in version 6u45

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
       String stringWithDottedI =  " \u0130 " ;
        Locale.setDefault(new Locale( " en " ,  " US " ));

        String lowerCasedString = stringWithDottedI.toLowerCase();

        assertEquals(stringWithDottedI.length(), lowerCasedString.length());

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
lowerCasedString.length() == 1
ACTUAL -
lowerCasedString.length() == 2

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package test;

import org.junit.Before;
import org.junit.Test;

import java.util.Locale;

import static org.junit.Assert.assertEquals;

public class StringTest {
    private final String stringWithDottedI =  " \u0130 " ;

    @Before
    public void setup() {
    }

    @Test
    public void testWhenLocaleIsTurkish_lowerCasedStringShouldHaveSameLength() {
        Locale.setDefault(new Locale( " tr " ,  " TR " ));

        String lowerCasedString = stringWithDottedI.toLowerCase();

        assertEquals(stringWithDottedI.length(), lowerCasedString.length());
    }

    @Test
    public void testWhenLocaleIsEnglish_lowerCasedStringShouldHaveSameLength() {
        Locale.setDefault(new Locale( " en " ,  " US " ));

        String lowerCasedString = stringWithDottedI.toLowerCase();

        assertEquals(stringWithDottedI.length(), lowerCasedString.length());
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
set default locale to Turkish ( new Locale( " tr " , " TR " ) )
or call  toLowerCase method which accepts a locale parameter and pass a Turkish locale parameter