CODEWITHSUNDEEP
javaperformance
ISJ
ISJ

Reputation: 37

Improving method performance java

A better solution?

   public String toString(byte[] array) {
        if (array == null)
            return "null";

            StringBuilder  sb = new StringBuilder(256).append('[');
            for (int j = 0; j < array.length; ++j) {
                sb.append(array[j]);
                if (j != array.length - 1)
                sb.append(", ");
            }
        return sb.append(']').toString();
    }

A better solution? If possible a more rapid solution to perform this method

Upvotes: 1

Views: 145

Answers (2)

Ebbe M. Pedersen
Ebbe M. Pedersen

Reputation: 7488

The following line:

sb.append(array[j]);

is sort of expensive, as it involves converting an int to a character representation and at the same time keeping track of the working buffer etc.

An alternative:

If you can live with a result like this:

[-123, 123, 002, 000,-022, 127]

instead of 

[-123, 123, 2, 0, -22, 127]

Then below method is 2 - 3 times faster on my machine:

    public String toString(byte[] array) {
        final char DIGITS[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
        if (array == null) {
            return "null";
        }

        char[] res = new char[(array.length * 5) + 1];

        int abs;
        int pos = 0;
        res[pos++] = '[';
        for (int i = 0; i < array.length; i++) {
            if (array[i] < 0) {
                abs = - array[i];
                res[pos++] = '-';
            } else {
                abs = array[i];
                res[pos++] = ' ';
            }
            res[pos++] = (abs >= 100 ? '1' : '0');
            int rest = (abs % 100); 
            res[pos++] = DIGITS[rest / 10]; 
            res[pos++] = DIGITS[rest % 10];
            res[pos++] = ',';
        }
        res[res.length - 1] = ']';

        return new String(res);
    }

Upvotes: 0

Juned Ahsan
Juned Ahsan

Reputation: 68715

Arrays.toString() returns a String representation of the specified array.Maybe this should suffice:

String s1 = Arrays.toString(byte);

Upvotes: 4

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