OnJava8-Examples/newio/LargeMappedFiles.java at network_tests · Java-Edge/OnJava8-Examples

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// newio/LargeMappedFiles.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

// Creating a very large file using mapping

import java.nio.*;

import java.nio.channels.*;

import java.io.*;

public class LargeMappedFiles {

static int length = 0x8000000; // 128 MB

public static void

main(String[] args) throws Exception {

try(RandomAccessFile tdat =

new RandomAccessFile("test.dat", "rw")) {

MappedByteBuffer out = tdat.getChannel()

.map(FileChannel.MapMode.READ_WRITE, 0, length);

for(int i = 0; i < length; i++)

out.put((byte)'x');

System.out.println("Finished writing");

for(int i = length/2; i < length/2 + 6; i++)

System.out.print((char)out.get(i));

}

/* Output:

Finished writing

xxxxxx