Example usage for java.io RandomAccessFile readByte

Introduction

In this page you can find the example usage for java.io RandomAccessFile readByte.

Prototype

public final byte readByte() throws IOException 

Source Link

Document

Reads a signed eight-bit value from this file.

Usage

From source file:Main.java

public static void main(String[] args) {
    try {/*from  ww  w.j  a  v  a  2  s  . c om*/
        byte[] b1 = { 15, 8 };

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");

        raf.writeByte(b1[0]);

        raf.seek(0);

        System.out.println(raf.readByte());

        raf.seek(0);

        raf.writeByte(b1[1]);

        raf.seek(0);

        System.out.println(raf.readByte());
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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From source file:ReverseFile.java

public static void main(String args[]) throws Exception {
    RandomAccessFile raf = new RandomAccessFile(args[0], "r");
    long position = raf.length();
    while (position > 0) {
        position -= 1;//from   w ww  .j a va  2s .co m
        raf.seek(position);
        byte b = raf.readByte();
        System.out.print((char) b);
    }
}

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From source file:Main.java

public static void main(String[] args) {
    try {//  w ww.  java 2s.  co m
        byte[] b = { 1 };

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");
        raf.write(b);

        // set the file pointer at 0 position
        raf.seek(0);

        System.out.println(raf.readByte());
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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From source file:Main.java

public static void main(String[] args) {
    try {//from   w  w  w .  j a v a2  s  .c o  m
        int b1 = 15;
        int b2 = 20;

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");
        raf.write(b1);

        // set the file pointer at 0 position
        raf.seek(0);

        System.out.println(raf.readByte());

        raf.write(b2);

        raf.seek(1);

        System.out.println(raf.readByte());
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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From source file:MainClass.java

public static void main(String args[]) {

    try {/*from  ww w  . j  av  a 2 s  .c  om*/

        RandomAccessFile raf = new RandomAccessFile(args[0], "r");

        long position = raf.length();

        while (position > 0) {

            position -= 1;

            raf.seek(position);
            byte b = raf.readByte();

            System.out.print((char) b);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

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From source file:Tail.java

public static void main(String args[]) throws Exception {
    RandomAccessFile raf = new RandomAccessFile(args[0], "r");
    long count = 10;
    long position = raf.length();
    position -= count;/*from w ww . j av  a2s.  co  m*/
    if (position < 0)
        position = 0;
    raf.seek(position);
    while (true) {
        try {
            byte b = raf.readByte();
            System.out.print((char) b);
        } catch (EOFException eofe) {
            break;
        }
    }
}

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From source file:Main.java

public static void main(String[] args) {
    try {// ww  w  . j  a va2 s.c om
        byte[] b = { 1, 2, 3, 4, 5, 6 };

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");

        // write 2 bytes in the file
        raf.write(b, 2, 2);

        // set the file pointer at 0 position
        raf.seek(0);

        // print the two bytes we wrote
        System.out.println(raf.readByte());
        System.out.println(raf.readByte());
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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From source file:Main.java

public static void main(String[] args) {
    try {//from ww w .j a  v  a2s .  co m

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");

        // write something in the file
        raf.writeUTF("Hello World from java2s.com");

        // set the file pointer at 0 position
        raf.seek(0);

        // read byte
        System.out.println(raf.readByte());

        // set the file pointer at 0 position
        raf.seek(0);

        // write 0 at the start
        raf.write(0);

        // read byte
        System.out.println(raf.readByte());
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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From source file:au.org.ala.layers.grid.GridCacheBuilder.java

static public float getNextValue(RandomAccessFile raf, Grid g) {
    float f = Float.NaN;
    try {//from w  w  w.j av a2  s. co  m
        int size;
        byte[] b;
        if (g.datatype.charAt(0) == 'B') {//"BYTE")) {
            f = raf.readByte();
        } else if (g.datatype.charAt(0) == 'U') {//equalsIgnoreCase("UBYTE")) {
            f = raf.readByte();
            if (f < 0) {
                f += 256;
            }
        } else if (g.datatype.charAt(0) == 'S') {//equalsIgnoreCase("SHORT")) {
            size = 2;
            b = new byte[size];
            raf.read(b);
            if (g.byteorderLSB) {
                f = (short) (((0xFF & b[1]) << 8) | (b[0] & 0xFF));
            } else {
                f = (short) (((0xFF & b[0]) << 8) | (b[1] & 0xFF));
            }
        } else if (g.datatype.charAt(0) == 'I') {//equalsIgnoreCase("INT")) {
            size = 4;
            b = new byte[size];
            raf.read(b);
            if (g.byteorderLSB) {
                f = ((0xFF & b[3]) << 24) | ((0xFF & b[2]) << 16) + ((0xFF & b[1]) << 8) + (b[0] & 0xFF);
            } else {
                f = ((0xFF & b[0]) << 24)
                        | ((0xFF & b[1]) << 16) + ((0xFF & b[2]) << 8) + ((0xFF & b[3]) & 0xFF);
            }
        } else if (g.datatype.charAt(0) == 'L') {//equalsIgnoreCase("LONG")) {
            size = 8;
            b = new byte[size];
            raf.read(b);
            if (g.byteorderLSB) {
                f = ((long) (0xFF & b[7]) << 56) + ((long) (0xFF & b[6]) << 48) + ((long) (0xFF & b[5]) << 40)
                        + ((long) (0xFF & b[4]) << 32) + ((long) (0xFF & b[3]) << 24)
                        + ((long) (0xFF & b[2]) << 16) + ((long) (0xFF & b[1]) << 8) + (0xFF & b[0]);
            } else {
                f = ((long) (0xFF & b[0]) << 56) + ((long) (0xFF & b[1]) << 48) + ((long) (0xFF & b[2]) << 40)
                        + ((long) (0xFF & b[3]) << 32) + ((long) (0xFF & b[4]) << 24)
                        + ((long) (0xFF & b[5]) << 16) + ((long) (0xFF & b[6]) << 8) + (0xFF & b[7]);
            }
        } else if (g.datatype.charAt(0) == 'F') {//.equalsIgnoreCase("FLOAT")) {
            size = 4;
            b = new byte[size];
            raf.read(b);
            ByteBuffer bb = ByteBuffer.wrap(b);
            if (g.byteorderLSB) {
                bb.order(ByteOrder.LITTLE_ENDIAN);
            }
            f = bb.getFloat();

        } else if (g.datatype.charAt(0) == 'D') {//.equalsIgnoreCase("DOUBLE")) {
            size = 8;
            b = new byte[8];
            raf.read(b);
            ByteBuffer bb = ByteBuffer.wrap(b);
            if (g.byteorderLSB) {
                bb.order(ByteOrder.LITTLE_ENDIAN);
            }
            f = (float) bb.getDouble();
        }
        //replace not a number            
        if ((float) f == (float) g.nodatavalue) {
            f = Float.NaN;
        }
    } catch (Exception e) {
    }
    return f;
}

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From source file:com.sangupta.snowpack.SnowpackRecover.java

/**
 * Try and recover from a chunk.//ww  w.  j  a  va2 s.co  m
 * 
 * @param chunkID
 * @param chunkFile
 * @param metadataDB 
 * @return
 * @throws IOException 
 */
private static ChunkInfo recoverChunkInfo(final int chunkID, final File chunkFile,
        SnowpackMetadataDB metadataDB) throws IOException {
    // open the file for reading
    RandomAccessFile raf = new RandomAccessFile(chunkFile, "r");

    // read the length first
    int nameLength, length, terminator, headerLength, numFiles = 0;
    long offset;

    List<FlakeMetadata> metas = new ArrayList<FlakeMetadata>();

    try {
        while (raf.getFilePointer() < raf.length()) {
            offset = raf.getFilePointer();

            nameLength = raf.readInt();
            byte[] name = new byte[nameLength];
            raf.readFully(name);

            length = raf.readInt();
            raf.readLong();
            raf.skipBytes((int) length);

            terminator = raf.readByte();
            if (terminator != 0) {
                System.out.print(" invalid descriptor found...");
                return null;
            }

            headerLength = 4 + name.length + 4 + 8;

            numFiles++;

            metas.add(new FlakeMetadata(new String(name), nameLength, chunkID, offset, headerLength));
        }
    } finally {
        raf.close();
    }

    // all clear for recovery

    // save all metadata in new DB
    for (FlakeMetadata meta : metas) {
        metadataDB.save(meta);
    }

    // return chunk info
    ChunkInfo info = new ChunkInfo();
    info.chunkID = chunkID;
    info.numFiles = numFiles;
    info.writePointer = -1;

    return info;
}

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