ByteToStringPerformanceTest

gistfile1.txt

package test;

import org.junit.Test;

public class StringPerformanceTest {

  @Test
  public void bytesToString() throws Exception {
    for (int i = 0; i < 10; i++) {
      bytesToString(10000000);
    }
  }

  public void bytesToString(final int count) throws Exception {
    long start, end;
    byte data[] = "MyData".getBytes();
    StringBuilder builder = new StringBuilder(16);
    char[] buffer = new char[16];

    for (int i = 0; i < 10; i++) {
      for (int j = 0; j < 10; j++) {
        new String(data);
      }
      Thread.sleep(100);
    }

    start = System.currentTimeMillis();
    for (int j = 0; j < count; j++) {
      new String(data);
    }
    end = System.currentTimeMillis();
    System.out.format("(new) duration: %d ms, ratio: %.4f", end - start, count / ((end - start) / 1000.0));
    System.out.println();

    for (int i = 0; i < 10; i++) {
      for (int j = 0; j < 10; j++) {
        stringBuilder(data, builder);
      }
      Thread.sleep(100);
    }

    start = System.currentTimeMillis();
    for (int j = 0; j < count; j++) {
      stringBuilder(data, builder);
    }
    end = System.currentTimeMillis();
    System.out.format("(builder) duration: %d ms, ratio: %.4f", end - start, count / ((end - start) / 1000.0));
    System.out.println();

    for (int i = 0; i < 10; i++) {
      for (int j = 0; j < 10; j++) {
        stringValueOf(data, buffer);
      }
      Thread.sleep(100);
    }

    start = System.currentTimeMillis();
    for (int j = 0; j < count; j++) {
      stringValueOf(data, buffer);
    }
    end = System.currentTimeMillis();
    System.out.format("(valueOf) duration: %d ms, ratio: %.4f", end - start, count / ((end - start) / 1000.0));
    System.out.println();
  }

  String stringBuilder(final byte[] data, final StringBuilder builder) {
    builder.delete(0, builder.length());
    for (int i = 0; i < data.length; i++) {
      builder.append((char) data[i]);
    }
    return builder.toString();
  }

  String stringValueOf(final byte[] data, final char[] buffer) {
    for (int i = 0; i < data.length; i++) {
      buffer[i] = (char) data[i];
    }
    return String.valueOf(buffer, 0, data.length);
  }

}