Java String Difference difference(String str1, String str2)

Description

difference

License

Mozilla Public License

Declaration

public static String difference(String str1, String str2) 

Method Source Code

//package com.java2s;
//License from project: Mozilla Public License 

public class Main {
    public static final String EMPTY = "";

    public static String difference(String str1, String str2) {
        if (str1 == null) {
            return str2;
        }//w  w w. j a v  a 2 s.  c  o  m

        if (str2 == null) {
            return str1;
        }

        int at = indexOfDifference(str1, str2);

        if (at == -1) {
            return EMPTY;
        }

        return str2.substring(at);
    }

    public static int indexOfDifference(String str1, String str2) {
        if (str1.equals(str2)) {
            return -1;
        }

        if (str1 == null || str2 == null) {
            return 0;
        }

        int i;

        for (i = 0; i < str1.length() && i < str2.length(); ++i) {
            if (str1.charAt(i) != str2.charAt(i)) {
                break;
            }
        }

        if (i < str2.length() || i < str1.length()) {
            return i;
        }

        return -1;
    }

    public static int indexOfDifference(String[] strs) {
        if (strs == null || strs.length <= 1) {
            return -1;
        }

        boolean anyStringNull = false;

        boolean allStringsNull = true;

        int arrayLen = strs.length;

        int shortestStrLen = Integer.MAX_VALUE;

        int longestStrLen = 0;

        for (int i = 0; i < arrayLen; i++) {
            if (strs[i] == null) {
                anyStringNull = true;

                shortestStrLen = 0;
            } else {
                allStringsNull = false;

                shortestStrLen = Math.min(strs[i].length(), shortestStrLen);

                longestStrLen = Math.max(strs[i].length(), longestStrLen);
            }
        }

        if (allStringsNull || (longestStrLen == 0 && !anyStringNull)) {
            return -1;
        }

        if (shortestStrLen == 0) {
            return 0;
        }

        int firstDiff = -1;

        for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) {
            char comparisonChar = strs[0].charAt(stringPos);

            for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) {
                if (strs[arrayPos].charAt(stringPos) != comparisonChar) {
                    firstDiff = stringPos;

                    break;
                }
            }

            if (firstDiff != -1) {
                break;
            }
        }

        if (firstDiff == -1 && shortestStrLen != longestStrLen) {
            return shortestStrLen;
        }

        return firstDiff;
    }

    public static String substring(String str, int start) {
        if (str == null) {
            return null;
        }

        if (start < 0) {
            start = str.length() + start;
        }

        if (start < 0) {
            start = 0;
        }

        if (start > str.length()) {
            return EMPTY;
        }

        return str.substring(start);
    }

    public static String substring(String str, int start, int end) {
        if (str == null) {
            return null;
        }

        if (end < 0) {
            end = str.length() + end;
        }

        if (start < 0) {
            start = str.length() + start;
        }

        if (end > str.length()) {
            end = str.length();
        }

        if (start > end) {
            return EMPTY;
        }

        if (start < 0) {
            start = 0;
        }

        if (end < 0) {
            end = 0;
        }

        return str.substring(start, end);
    }

    public static boolean equals(String str1, String str2) {
        return str1 == null ? str2 == null : str1.equals(str2);
    }

    public static int length(String str) {
        return str == null ? 0 : str.length();
    }
}

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