Java Reference
In-Depth Information
Display 10.22
Random Access to a File
(part 1 of 2)
1
import
java.io.RandomAccessFile;
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import
java.io.IOException;
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import
java.io.FileNotFoundException;
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public class
RandomAccessDemo
5{
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public static void
main(String[] args)
7 {
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try
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{
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RandomAccessFile ioStream =
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new
RandomAccessFile("bytedata", "rw");
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System.out.println("Writing 3 bytes to the file bytedata.");
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ioStream.writeByte(1);
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ioStream.writeByte(2);
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ioStream.writeByte(3);
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System.out.println("The length of the file is now = "
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+ ioStream.length());
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System.out.println("The file pointer location is "
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+ ioStream.getFilePointer());
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System.out.println("Moving the file pointer to location 1.");
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ioStream.seek(1);
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byte oneByte = ioStream.readByte();
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System.out.println("The value at location 1 is " + oneByte);
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oneByte = ioStream.readByte();
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System.out.println("The value at the next location is "
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+ oneByte);
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System.out.println("Now we move the file pointer back to");
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System.out.println("location 1, and change the byte.");
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ioStream.seek(1);
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ioStream.writeByte(9);
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ioStream.seek(1);
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oneByte = ioStream.readByte();
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System.out.println("The value at location 1 is now " + oneByte);
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System.out.println("Now we go to the end of the file");
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System.out.println("and write a double.");
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ioStream.seek(ioStream.length());
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ioStream.writeDouble(41.99);
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System.out.println("The length of the file is now = "
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+ ioStream.length());
