şöyle olabilir

int count = StringUtils.countMatches("a.b.c.d", ".");

veya

int count = line.length() - line.replace(".", "").length();

veya

int replaceAll = testString.replaceAll("[^.]", "").length();

veya

int replaceAllCase2 = testString.length() - testString.replaceAll("\\.", "").length();

veya

int split = testString.split("\\.",-1).length-1;