asullaherc asullaherc - 21 days ago 4
Bash Question

How to implement shell "ls -v" in java

For example, I run

ls -v /tmp/chk
get:

ar1 ar20 ar100 pr1 pr20 pr100


but when I use following groovy code:

new File("/tmp/chk").listFiles().sort().each {
println it.name
}


the result is:

ar1
ar100
ar20
pr1
pr100
pr20


How to implement
ls -v
algorithm to get same order in java or groovy

Answer

Following code implement alphanumeric sort

public class NaturalOrderComparator implements Comparator {
    int compareRight(String a, String b) {
        int bias = 0;
        int ia = 0;
        int ib = 0;

        // The longest run of digits wins. That aside, the greatest
        // value wins, but we can't know that it will until we've scanned
        // both numbers to know that they have the same magnitude, so we
        // remember it in BIAS.
        for (; ; ia++, ib++) {
            char ca = charAt(a, ia);
            char cb = charAt(b, ib);

            if (!Character.isDigit(ca) && !Character.isDigit(cb)) {
                return bias;
            } else if (!Character.isDigit(ca)) {
                return -1;
            } else if (!Character.isDigit(cb)) {
                return +1;
            } else if (ca < cb) {
                if (bias == 0) {
                    bias = -1;
                }
            } else if (ca > cb) {
                if (bias == 0)
                    bias = +1;
            } else if (ca == 0 && cb == 0) {
                return bias;
            }
        }
    }

    public int compare(Object o1, Object o2) {
        String a = o1.toString();
        String b = o2.toString();

        int ia = 0, ib = 0;
        int nza = 0, nzb = 0;
        char ca, cb;
        int result;

        while (true) {
            // only count the number of zeroes leading the last number compared
            nza = nzb = 0;

            ca = charAt(a, ia);
            cb = charAt(b, ib);

            // skip over leading spaces or zeros
            while (Character.isSpaceChar(ca) || ca == '0') {
                if (ca == '0') {
                    nza++;
                } else {
                    // only count consecutive zeroes
                    nza = 0;
                }

                ca = charAt(a, ++ia);
            }

            while (Character.isSpaceChar(cb) || cb == '0') {
                if (cb == '0') {
                    nzb++;
                } else {
                    // only count consecutive zeroes
                    nzb = 0;
                }

                cb = charAt(b, ++ib);
            }

            // process run of digits
            if (Character.isDigit(ca) && Character.isDigit(cb)) {
                if ((result = compareRight(a.substring(ia), b.substring(ib))) != 0) {
                    return result;
                }
            }

            if (ca == 0 && cb == 0) {
                // The strings compare the same. Perhaps the caller
                // will want to call strcmp to break the tie.
                return nza - nzb;
            }

            if (ca < cb) {
                return -1;
            } else if (ca > cb) {
                return +1;
            }

            ++ia;
            ++ib;
        }
    }

    static char charAt(String s, int i) {
        if (i >= s.length()) {
            return 0;
        } else {
            return s.charAt(i);
        }
    }

    public static void main(String[] args) {
        String[] strings = new String[]{"1-2", "1-02", "1-20", "10-20", "fred", "jane", "pic01",
                "pic2", "pic02", "pic02a", "pic3", "pic4", "pic 4 else", "pic 5", "pic05", "pic 5",
                "pic 5 something", "pic 6", "pic   7", "pic100", "pic100a", "pic120", "pic121",
                "pic02000", "tom", "x2-g8", "x2-y7", "x2-y08", "x8-y8"};

        List orig = Arrays.asList(strings);

        System.out.println("Original: " + orig);

        List scrambled = Arrays.asList(strings);
        Collections.shuffle(scrambled);

        System.out.println("Scrambled: " + scrambled);

        Collections.sort(scrambled, new NaturalOrderComparator());

        System.out.println("Sorted: " + scrambled);
    }
}
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