@Test
public void testStringReplaxeAll() {
	String in1 = "qwe asd, ZXC";
	String in2 = "ФЫВ, ЙЦУ ячс";

	String out1 = in1.replaceAll("\\W+", "");
	String out2 = in2.replaceAll("\\W+", "");

	assertEquals("qweasdZXC", out1);
	assertEquals("ФЫВЙЦУячс", out2); // org.junit.ComparisonFailure: expected:<[ФЫВЙЦУячс]> but was:<[]>
}

@Test
public void testStringPatternUnicode() {
	Pattern pattern = Pattern.compile("\bФЫВ\b", Pattern.UNICODE_CHARACTER_CLASS);
	Matcher matcher = pattern.matcher("ФЫВФЫВ, ФЫВ");
	assertTrue(matcher.matches()); // java.lang.AssertionError 
}

@Test
public void testStringReplaceAllUnicode() {
	String in1 = "ФЫВФЫВ, ФЫВ";
	String out1 = in1.replaceAll("(?U)\bФЫВ\b", "фыв");
	assertEquals("ФЫВФЫВ, фыв", out1); // org.junit.ComparisonFailure: expected:<ФЫВФЫВ, [фыв]> but was:<ФЫВФЫВ, [ФЫВ]>
}

\b => (?:(?<=[\pL\pM\p{Nd}\p{Nl}\p{Pc}[\p{InEnclosedAlphanumerics}&&\p{So}]])(?![\pL\pM\p{Nd}\p{Nl}\p{Pc}
	[\p{InEnclosedAlphanumerics}&&\p{So}]])|(?<![\pL\pM\p{Nd}\p{Nl}\p{Pc}[\p{InEnclosedAlphanumerics}&&\p{So}]])
	(?=[\pL\pM\p{Nd}\p{Nl}\p{Pc}[\p{InEnclosedAlphanumerics}&&\p{So}]]))