Performance of StringBuilder + Write

gistfile1.java

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.Writer;

import org.junit.Test;

public class SizeTest {

  @Test
	public void write_stringbuilder_to_file() throws Exception {
		final long startTime = System.currentTimeMillis();
		printMemoryInfo();
		final StringBuilder builder = new StringBuilder(200 * 10000);
		for (int i = 0; i < 10000; i++) {
			builder.append("a text line that is about two hundred characters ........................................................................");
		}
		final long endTime1 = System.currentTimeMillis();
		System.out.println("String Builder Creation Time in ms: " + (endTime1 - startTime));
		System.out.println("StringBuilder size: " + builder.length());
		printMemoryInfo();

		final Writer writer = new BufferedWriter(new FileWriter("/tmp/out.txt"));
		writer.append(builder.toString());

		final long endTime2 = System.currentTimeMillis();
		System.out.println("File Writing Time in ms: " + (endTime2 - endTime1));
		System.out.println("Total Elapsed Time in ms: " + (endTime2 - startTime));
		printMemoryInfo();
	}

	private void printMemoryInfo() {
		final Runtime rt = Runtime.getRuntime();
		System.out.println("(MB) Total Memory: " + mb(rt.totalMemory()) + " Free Memory: " + mb(rt.freeMemory()) + " Max Memory: " + mb(rt.maxMemory()));

	}

	private long mb(final long memory) {
		return memory / 1024 / 1024;
	}
}