Stream Write: 0.37
Mapped Write: Exception in thread "main" java.nio.BufferOverflowException
        at java.nio.Buffer.nextPutIndex(Buffer.java:521)
        at java.nio.DirectIntBufferS.put(DirectIntBufferS.java:297)
        at
com.thinkInJava.study.ioSystem.MappedIO$2.test(MappedIO.java:52)
        at
com.thinkInJava.study.ioSystem.MappedIO$Tester.runTest(MappedIO.java:21)
        at
com.thinkInJava.study.ioSystem.MappedIO.main(MappedIO.java:106)

import java.nio.*;
        import java.nio.channels.*;
        import java.io.*;

        public class MappedIO {
            //Byte size
            private static int numOfInts = 4000000;
            private static int numOfUbuffInts = 200000;
            //Test run time
            private abstract static class Tester {
                private String name;
                public Tester(String name) { this.name = name; }
                public void runTest() {
                    System.out.print(name + ": ");
                    try {
                        long start = System.nanoTime();
                        test();
                        double duration = System.nanoTime() - start;
                        //Convert to seconds
                        System.out.format("%.2fn", duration/1.0e9);
                    } catch(IOException e) {
                        throw new RuntimeException(e);
                    }
                }
                public abstract void test() throws IOException;
            }

        //Compare the performance of six io streams
        private static Tester[] tests = {
                new Tester("Stream Write") {
                    public void test() throws IOException {
                        DataOutputStream dos = new DataOutputStream(
                                new BufferedOutputStream(
                                        new FileOutputStream(new File("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFiles\temp.tmp"))));
                        for(int i = 0; i < numOfInts; i++)
                            dos.writeInt(i);
                        dos.close();
                    }
                },
                new Tester("Mapped Write") {
                    public void test() throws IOException {
                        FileChannel fc =
                                new RandomAccessFile("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFilestemp.tmp", "rw")
                                        .getChannel();
                        IntBuffer ib = fc.map(
                                FileChannel.MapMode.READ_WRITE, 0, fc.size())
                                .asIntBuffer();
                        for(int i = 0; i < numOfInts; i++)
                            ib.put(i);
                        fc.close();
                    }
                },
                new Tester("Stream Read") {
                    public void test() throws IOException {
                        DataInputStream dis = new DataInputStream(
                                new BufferedInputStream(
                                        new FileInputStream("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFilestemp.tmp")));
                        for(int i = 0; i < numOfInts; i++)
                            dis.readInt();
                        dis.close();
                    }
                },
                new Tester("Mapped Read") {
                    public void test() throws IOException {
                        FileChannel fc = new FileInputStream(
                                new File("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFilestemp.tmp")).getChannel();
                        IntBuffer ib = fc.map(
                                FileChannel.MapMode.READ_ONLY, 0, fc.size())
                                .asIntBuffer();
                        while(ib.hasRemaining())
                            ib.get();
                        fc.close();
                    }
                },
                new Tester("Stream Read/Write") {
                    public void test() throws IOException {
                        RandomAccessFile raf = new RandomAccessFile(
                                new File("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFilestemp.tmp"), "rw");
                        raf.writeInt(1);
                        for(int i = 0; i < numOfUbuffInts; i++) {
                            raf.seek(raf.length() - 4);
                            raf.writeInt(raf.readInt());
                        }
                        raf.close();
                    }
                },
                new Tester("Mapped Read/Write") {
                    public void test() throws IOException {
                        FileChannel fc = new RandomAccessFile(
                                new File("X:\IntelliJ IDEA 2019.1.3\JavaCode\src\com\thinkInJava\study\ioSystem\TestFilestemp.tmp"), "rw").getChannel();
                        IntBuffer ib = fc.map(
                                FileChannel.MapMode.READ_WRITE, 0, fc.size())
                                .asIntBuffer();
                        ib.put(0);
                        for(int i = 1; i < numOfUbuffInts; i++)
                            ib.put(ib.get(i - 1));
                        fc.close();
                    }
                }
        };
        public static void main(String[] args) {
            for(Tester test : tests)
                test.runTest();
        }
    }