Java String Snake Case toSnakeCase(String str, boolean capitalize, Boolean upper)

Description

to Snake Case

License

MIT License

Declaration

public static String toSnakeCase(String str, boolean capitalize, Boolean upper) 

Method Source Code

//package com.java2s;
/*!// w  ww . ja v a  2 s.  c o m
 * mifmi-commons4j
 * https://github.com/mifmi/mifmi-commons4j
 *
 * Copyright (c) 2015 mifmi.org and other contributors
 * Released under the MIT license
 * https://opensource.org/licenses/MIT
 */

public class Main {
    public static String toSnakeCase(String str, boolean capitalize, Boolean upper) {
        return changeSeparator(str, '_', capitalize, null, upper);
    }

    public static String changeSeparator(String str, int separatorChar, boolean capitalize, Boolean firstCapital,
            Boolean upper) {
        if (str == null) {
            return null;
        }

        int len = str.length();

        if (len == 0) {
            return "";
        }

        int cnt = Character.codePointCount(str, 0, len);

        StringBuilder sb = new StringBuilder(len);
        boolean inWord = false;
        boolean isFirstWord = false;
        boolean isFirstLineWord = true;
        boolean isBeforeUpper = false;
        for (int i = 0; i < cnt; i++) {
            int cp = str.codePointAt(i);

            if (isASCII(cp)) {
                if (Character.isAlphabetic(cp) || Character.isDigit(cp)) {
                    if (Character.isUpperCase(cp)) {
                        isFirstWord = !isBeforeUpper;
                        if (!isFirstWord && i + 1 < cnt) {
                            int ncp = str.codePointAt(i + 1);
                            if (Character.isAlphabetic(ncp)
                                    && !(Character.isUpperCase(ncp) || Character.isDigit(cp))) {
                                isFirstWord = true;
                            }
                        }
                        isBeforeUpper = true;
                    } else {
                        isFirstWord = !inWord;
                        isBeforeUpper = false;
                    }
                    inWord = true;
                } else if (cp == '\r' || cp == '\n') {
                    isFirstWord = false;
                    inWord = false;
                    isBeforeUpper = false;

                    isFirstLineWord = true;
                } else {
                    isFirstWord = false;
                    inWord = false;
                    isBeforeUpper = false;
                }
            } else {
                isFirstWord = !inWord;
                inWord = true;
                isBeforeUpper = false;
            }

            if (inWord) {
                if (isFirstWord) {
                    if (isFirstLineWord) {
                        isFirstLineWord = false;
                    } else {
                        if (0 <= separatorChar) {
                            sb.append((char) separatorChar);
                        }
                    }
                }
                if (capitalize) {
                    if (isFirstWord) {
                        if (i == 0) {
                            if (firstCapital == null || firstCapital.booleanValue()) {
                                sb.appendCodePoint(Character.toUpperCase(cp));
                            } else {
                                sb.appendCodePoint(Character.toLowerCase(cp));
                            }
                        } else {
                            sb.appendCodePoint(Character.toUpperCase(cp));
                        }
                    } else {
                        sb.appendCodePoint(Character.toLowerCase(cp));
                    }
                } else {
                    if (upper == null) {
                        sb.appendCodePoint(cp);
                    } else if (upper.booleanValue()) {
                        sb.appendCodePoint(Character.toUpperCase(cp));
                    } else {
                        sb.appendCodePoint(Character.toLowerCase(cp));
                    }
                }
            } else {
                if (cp == '\r' || cp == '\n') {
                    sb.appendCodePoint(cp);
                }
            }
        }

        return sb.toString();
    }

    public static boolean isASCII(char c) {
        if ('\u007F' < c) {
            return false;
        }
        return true;
    }

    public static boolean isASCII(int codePoint) {
        if ('\u007F' < codePoint) {
            return false;
        }
        return true;
    }

    public static boolean isASCII(String str) {
        if (str == null || str.isEmpty()) {
            return true;
        }
        int len = str.length();
        for (int i = 0; i < len; i++) {
            char ch = str.charAt(i);
            if (!isASCII(ch)) {
                return false;
            }
        }
        return true;
    }

    public static String toString(StringBuilder sb, boolean trim) {
        if (sb == null) {
            return null;
        }

        if (!trim) {
            return sb.toString();
        }

        int len = sb.length();
        if (len == 0) {
            return "";
        }

        int sIdx;
        for (sIdx = 0; sIdx < len; sIdx++) {
            char ch = sb.charAt(sIdx);
            if (!Character.isWhitespace(ch)) {
                break;
            }
        }

        if (sIdx == len) {
            return "";
        }

        int eIdx;
        for (eIdx = len - 1; 0 <= eIdx; eIdx--) {
            char ch = sb.charAt(eIdx);
            if (!Character.isWhitespace(ch)) {
                break;
            }
        }

        return sb.substring(sIdx, eIdx + 1);
    }
}

Related

1. toSnakeCase(String camelCase)
2. toSnakeCase(String s)
3. toSnakeCase(String src)
4. toSnakeCase(String str)
5. toSnakeCase(String str)