strip bench

import java.util.Random;

public class Main {

    static interface StripAlg {
        String strip(String old);
        String name();
    }

    private final static StripAlg strip1 = new StripAlg() {
        @Override
        public String strip(final String old) {
            final int length = old.length();
            final char[] oldChars = new char[length];
            old.getChars(0, length, oldChars, 0);
            int newLen = 0;
            for(int j = 0; j < length; j++) {
                final char ch = oldChars[j];
                if (ch >= ' ') {
                    oldChars[newLen] = ch;
                    newLen++;
                }
            }
            return new String(oldChars, 0, newLen);
        }

        @Override
        public String name() {
            return "Alg1";
        }
    };

    private final static StripAlg strip2 = new StripAlg() {
        @Override
        public String strip(final String old) {
            final StringBuffer sb = new StringBuffer(old.length());
            for(int i = 0; i < old.length(); i++) {
                final char ch = old.charAt(i);
                if (ch >= ' ') {
                    sb.append(ch);
                }
            }
            return sb.toString();
        }

        @Override
        public String name() {
            return "Alg2";
        }
    };

    private final static StripAlg strip3 = new StripAlg() {
        @Override
        public String strip(final String old) {
            final int length = old.length();
            final char[] oldChars = new char[length + 1];
            old.getChars(0, length, oldChars, 0);
            oldChars[length] = '\0';// avoiding explicit bound check in while
            int newLen = -1;
            while(oldChars[++newLen] >= ' ')
                ;// find first non-printable,
            // if there are none it ends on the null char I appended
            for(int j = newLen; j < length; j++) {
                final char ch = oldChars[j];
                if (ch >= ' ') {
                    oldChars[newLen] = ch;// the while avoids repeated
                                            // overwriting here when newLen==j
                    newLen++;
                }
            }
            return new String(oldChars, 0, newLen);
        }

        @Override
        public String name() {
            return "Alg3";
        }
    };

    private static String getTestString(final int size, final int maxCharVal, final long seed) {
        final Random rand = new Random(seed);
        final StringBuffer sb = new StringBuffer(size);
        for(int i = 0; i < size; i++) {
            sb.append((char) rand.nextInt(maxCharVal));
        }
        return sb.toString();
    }

    private static double testAlg(final StripAlg alg, final String test, final int runs) {
        final long start = System.nanoTime();
        for(int i = 0; i < runs; i++) {
            alg.strip(test);
        }
        final long end = System.nanoTime();
        return (double)(end - start) / 1000000;
    }

    public static void main(final String[] args) {
        final long seed = 0xdeadcafe;
        final int size = 200;
        final int maxCharVal = 200; // 32/200 ~ percentage of non printables
        final String test = getTestString(size, maxCharVal, seed);
        final int nrRuns = 10000;

        final StripAlg algs[] = { strip1, strip2, strip3 };
        for(final StripAlg alg : algs) {
            getTime(alg, size, test, nrRuns);
        }

    }

    private static void getTime(final StripAlg alg, final int size, final String test,
            final int nrRuns) {
        double minRun = Double.MAX_VALUE;
        for(int i = 0; i < 1000; i++) {
            minRun = Math.min(minRun, testAlg(alg, test, nrRuns));
        }
        System.out.printf("%s takes %.2fms per %d elements (%.2fops/s)%n", alg.name(), minRun, nrRuns,
                (double) nrRuns / minRun * 1000);
    }

}