String 经常用法最优算法实现总结 （二）

1. String getOrderedString(boolean isDuplicated, String … str)

说明：

Orders all characters in the input strings and return the ordered string.(note: only considering the alphabets and digits)

i.e:

(false, {"ahcdx", "abcuy", "cejm"}) ->"abcdehjmuxy"

(true, {"ahcdx", "abcuy", "cejm"}) ->"aabcdehjmuxy"

/**
* Orders all characters in the input strings without duplicated str.
*
* @Title: getOrderedString
* @param isDuplicated true/false
* @param str input str
* @return ordered string
*/
public static String getOrderedString(boolean isDuplicated, String... str) {
if (str == null || str.length == 0) {
return null;
}

// initialize array
int[] charArrayTmp = new int[MAX_CHAR_LENGTH];
System.arraycopy(CHARARRAY, 0, charArrayTmp, 0, MAX_CHAR_LENGTH);

int length = str.length;
String value = null;
int valueLength = 0;
char tempValue;
int totalCounts = 0;

// merge and sort the input strs
for (int i = 0; i < length; i++) {
value = str[i];
valueLength = value.length();
totalCounts += valueLength;

for (int j = 0; j < valueLength; j++) {
tempValue = value.charAt(j);

if (isDuplicated) {
charArrayTmp[tempValue] += 1;
} else {
charArrayTmp[tempValue] = 1;
}

}
}

char[] newChar = new char[totalCounts];
int counts = 0;
int len = 0;
// append result that has been merged and sorted
for (int i = MIN_CHAR_LENGTH; i < MAX_CHAR_LENGTH; i++) {
len = charArrayTmp[i];

if (len != 0) {
for (int j = 0; j < len; j++) {
newChar[counts++] = (char) i;
}
}

}
return new String(newChar, 0, counts);
}

2. List<String> getMostLongDifferent(String str)
说明：
Returns the longest consecutive different substring.

i.e:

("abcabefg") -> "cabefg"

/**
* @Description: get the longest consecutive different substring.
* @Title: getMostLongDifferent
* @param str input string
* @return the longest consecutive different substring of input
*/
public static List<String> getMostLongDifferent(String str) {
if (isEmpty(str)) {
return null;
}
int len = str.length();
Map<Character, Integer> cursor = new HashMap<Character, Integer>();
cursor.put(str.charAt(0), 0);
int[] lengthAt = new int[len];
lengthAt[0] = 1;
int max = 0;
for (int i = 1; i < len; i++) {
char cha = str.charAt(i);

if (cursor.containsKey(cha)) {
lengthAt[i] = Math.min(lengthAt[i - 1] + 1, i - cursor.get(cha));
} else {
lengthAt[i] = lengthAt[i - 1] + 1;
}
max = (max >= lengthAt[i]) ? max : lengthAt[i];
cursor.put(cha, i);
}

List<String> resultList = new ArrayList<String>();
for (int i = 0; i < len; i++) {
if (max == lengthAt[i]) {
String resultString = str.substring(i - max + 1, i + 1);
if (!resultList.contains(resultString)) {
resultList.add(resultString);
}
}
}
return resultList;
}

3. String normalizeSpace(String str)
说明：
Remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.

/**
* Remove leading and trailing whitespace and then replacing sequences of whitespace characters.
* by a single space
*
* @param str the string need to be normalize space
* @return string result after normalize space
*/
public static String normalizeSpace(String str) {
if (str == null) {
return null;
}

str = str.trim();

if (str.length() <= 3) {
return str;
}

if (str.indexOf(CommonConstants.DOUBLE_BLANKS, 1) >= 0) {
char[] chars = str.toCharArray();
int index = 0;

for (int i = 0, len = chars.length; i < len; i++) {
if (chars[i] != CommonConstants.CHAR_BLANKS || chars[i - 1] != CommonConstants.CHAR_BLANKS) {
chars[index++] = chars[i];
}
}

return new String(chars, 0, index);
} else {
return str;
}
}