Java String StringBuffer StringBuilder 效率测试

package ersatz;

import java.io.FileNotFoundException;

public class Ersatz {
  public static void main(String[] args) throws FileNotFoundException {
    long commenceTime = 0L;
    long closureTime = 0L;
    StringBuffer buffer = new StringBuffer("");

    commenceTime = System.currentTimeMillis();
    for (int i = 0; i < 80000; ++i) {
      buffer.append(String.valueOf(i));
    }
    closureTime = System.currentTimeMillis();
    System.out.println("StringBuffer elapsed: " + (closureTime - commenceTime));

    StringBuilder builder = new StringBuilder("");
    commenceTime = System.currentTimeMillis();
    for (int i = 0; i < 80000; ++i) {
      builder.append(String.valueOf(i));
    }
    closureTime = System.currentTimeMillis();
    System.out.println("StringBuilder elapsed: " + (closureTime - commenceTime));
    String str = "";
    commenceTime = System.currentTimeMillis();
    for (int i = 0; i < 80000; ++i) {
      str += String.valueOf(i);
    }
    closureTime = System.currentTimeMillis();
    System.out.println("String elapsed: " + (closureTime - commenceTime));
  }
}