WriterBenchmark.java

import java.io.*;

public class WriterBenchmark {
    public static final int N = 1000000;

    public static void main(String... args) throws IOException, InterruptedException  {
        long sum = 0;
    
        for (int i = 0; i < 200; i++) {
            long start = System.nanoTime();

            writeDirectly();
            // withBufferedWriter();
            // buffered();

            long time = System.nanoTime() - start;

            System.out.println(i + " " + time / 1000.0 / 1000.0);

            if (i >= 150) {
                sum += time;
                Thread.sleep(100);
            }
        }

        System.out.println(sum / 50.0 / 1000.0 / 1000.0);
    }

    public static void writeDirectly() throws IOException {
        Writer writer = new FileWriter("test.dat");

        try {
            for (int i = 0; i < N; i++) {
                writer.write("1");
            }
        } finally {
            writer.close();
        }
    }

    public static void withBufferedWriter() throws IOException {
        Writer writer = new BufferedWriter(new FileWriter("test.dat"));

        try {
            for (int i = 0; i < N; i++) {
                writer.write("1");
            }
        } finally {
            writer.close();
        }
    }

    public static void buffered() throws IOException {
        StringBuilder builder = new StringBuilder();

        for (int i = 0; i < N; i++) {
            builder.append("1");
        }

        FileWriter writer = new FileWriter("test.dat");

        try {
            writer.write(builder.toString());
        } finally {
            writer.close();
        }
    }
}