Java String Difference difference(String str1, String str2)

Description

difference

License

Open Source License

Declaration

public static String difference(String str1, String str2) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    public static final int INDEX_NOT_FOUND = -1;
    public static final String EMPTY = "";

    public static String difference(String str1, String str2) {
        if (str1 == null) {
            return str2;
        }//from ww  w.jav a  2 s .co  m
        if (str2 == null) {
            return str1;
        }
        int at = indexOfDifference(str1, str2);
        if (at == INDEX_NOT_FOUND) {
            return EMPTY;
        }
        return str2.substring(at);
    }

    public static int indexOfDifference(CharSequence cs1, CharSequence cs2) {
        if (cs1 == cs2) {
            return INDEX_NOT_FOUND;
        }
        if (cs1 == null || cs2 == null) {
            return 0;
        }
        int i;
        for (i = 0; i < cs1.length() && i < cs2.length(); ++i) {
            if (cs1.charAt(i) != cs2.charAt(i)) {
                break;
            }
        }
        if (i < cs1.length() || i < cs2.length()) {
            return i;
        }
        return INDEX_NOT_FOUND;
    }

    public static int indexOfDifference(CharSequence... css) {
        if (css == null || css.length <= 1) {
            return INDEX_NOT_FOUND;
        }
        boolean anyStringNull = false;
        boolean allStringsNull = true;
        int arrayLen = css.length;
        int shortestStrLen = Integer.MAX_VALUE;
        int longestStrLen = 0;

        for (int i = 0; i < arrayLen; i++) {
            if (css[i] == null) {
                anyStringNull = true;
                shortestStrLen = 0;
            } else {
                allStringsNull = false;
                shortestStrLen = Math.min(css[i].length(), shortestStrLen);
                longestStrLen = Math.max(css[i].length(), longestStrLen);
            }
        }
        if (allStringsNull || longestStrLen == 0 && !anyStringNull) {
            return INDEX_NOT_FOUND;
        }
        if (shortestStrLen == 0) {
            return 0;
        }

        int firstDiff = -1;
        for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) {
            char comparisonChar = css[0].charAt(stringPos);
            for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) {
                if (css[arrayPos].charAt(stringPos) != comparisonChar) {
                    firstDiff = stringPos;
                }
            }
            if (firstDiff != -1) {
                break;
            }
        }

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

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