private String getCaseCorrectedLookupString(LookupElement item) { String lookupString = item.getLookupString(); if (item.isCaseSensitive()) { return lookupString; } final String prefix = itemPattern(item); final int length = prefix.length(); if (length == 0 || !itemMatcher(item).prefixMatches(prefix)) return lookupString; boolean isAllLower = true; boolean isAllUpper = true; boolean sameCase = true; for (int i = 0; i < length && (isAllLower || isAllUpper || sameCase); i++) { final char c = prefix.charAt(i); boolean isLower = Character.isLowerCase(c); boolean isUpper = Character.isUpperCase(c); // do not take this kind of symbols into account ('_', '@', etc.) if (!isLower && !isUpper) continue; isAllLower = isAllLower && isLower; isAllUpper = isAllUpper && isUpper; sameCase = sameCase && isLower == Character.isLowerCase(lookupString.charAt(i)); } if (sameCase) return lookupString; if (isAllLower) return lookupString.toLowerCase(); if (isAllUpper) return StringUtil.toUpperCase(lookupString); return lookupString; }