Example usage for java.io RandomAccessFile seek

Introduction

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

Prototype

public void seek(long pos) throws IOException 

Source Link

Document

Sets the file-pointer offset, measured from the beginning of this file, at which the next read or write occurs.

Usage

From source file:Main.java

public static void main(String[] args) {
    try {/*from w  ww . j  av  a 2 s . 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:Main.java

public static void main(String[] args) {
    try {/*from   w w  w  . java 2  s .  c o  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 boolean
        System.out.println(raf.readBoolean());

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

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

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

}

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From source file:MainClass.java

public static void main(String[] args) {
    try {/*ww w. j a  v a2 s . c  om*/
        RandomAccessFile raf = new RandomAccessFile("c:\\temp\\RAFsample.txt", "rw");
        raf.writeInt(10);
        raf.writeInt(43);
        raf.writeInt(88);
        raf.writeInt(455);

        // change the 3rd integer from 88 to 99
        raf.seek((3 - 1) * 4);
        raf.writeInt(99);
        raf.seek(0); // go to the first integer
        int i = raf.readInt();
        while (i != -1) {
            System.out.println(i);

            i = raf.readInt();
        }
        raf.close();
    } catch (IOException e) {
    }
}

---

From source file:org.commoncrawl.service.queryserver.master.S3Helper.java

public static void main(String[] args) {
    File arcFile = new File(args[0]);
    long offset = Long.parseLong(args[1]);
    long contentSize = Long.parseLong(args[2]);

    try {/* ww w . j  a  v  a  2 s.  c  o  m*/
        RandomAccessFile fileHandle = new RandomAccessFile(arcFile, "r");

        fileHandle.seek(Math.max(offset - 10, 0));

        byte data[] = new byte[(int) contentSize + 10];
        fileHandle.readFully(data);

        ByteBuffer buffer = ByteBuffer.wrap(data);
        buffer.position(0);

        int position = scanForGZIPHeader(buffer.slice());

        buffer.position(position);

        StreamingArcFileReader reader = new StreamingArcFileReader(false);
        reader.available(buffer);
        ArcFileItem nextItem = reader.getNextItem();
        System.out.println(nextItem.getUri());

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

---

From source file:Main.java

public static void main(String[] args) throws Exception {
    RandomAccessFile raf = new RandomAccessFile("books.dat", "rw");

    String books[] = new String[5];
    books[0] = "A";
    books[1] = "B";
    books[2] = "C";
    books[3] = "D";
    books[4] = "E";

    for (int i = 0; i < books.length; i++) {
        raf.writeUTF(books[i]);// w ww.j a  va 2 s.com
    }
    raf.seek(raf.length());
    raf.writeUTF("Servlet & JSP Programming");

    raf.seek(0);

    while (raf.getFilePointer() < raf.length()) {
        System.out.println(raf.readUTF());
    }
}

---

From source file:Main.java

License:asdf

public static void main(String[] args) throws Exception {
    RandomAccessFile randomAccessFile = null;

    String line1 = "line\n";
    String line2 = "asdf1234\n";

    // read / write permissions
    randomAccessFile = new RandomAccessFile("yourFile.dat", "rw");

    randomAccessFile.writeBytes(line1);//w w  w . j a  v a2  s. c o m
    randomAccessFile.writeBytes(line2);

    // Place the file pointer at the end of the first line
    randomAccessFile.seek(line1.length());

    byte[] buffer = new byte[line2.length()];
    randomAccessFile.read(buffer);
    System.out.println(new String(buffer));

    randomAccessFile.close();
}

---

From source file:Main.java

License:asdf

public static void main(String[] args) throws Exception {
    RandomAccessFile randomAccessFile = null;

    String line1 = "java2s.com\n";
    String line2 = "asdf1234\n";

    // read / write permissions
    randomAccessFile = new RandomAccessFile("yourFile.dat", "rw");

    randomAccessFile.writeBytes(line1);/*from   w w w. j  a  va  2 s  . c  o m*/
    randomAccessFile.writeBytes(line2);

    // Place the file pointer at the end of the first line
    randomAccessFile.seek(line1.length());

    byte[] buffer = new byte[line2.length()];
    randomAccessFile.read(buffer);
    System.out.println(new String(buffer));

    randomAccessFile.close();
}

---

From source file:RandomFileTest.java

public static void main(String[] args) {
    Employee[] staff = new Employee[3];

    staff[0] = new Employee("Harry Hacker", 35000);
    staff[1] = new Employee("Carl Cracker", 75000);
    staff[2] = new Employee("Tony Tester", 38000);
    try {/*from  w  w  w. ja  v a2 s. c om*/
        DataOutputStream out = new DataOutputStream(new FileOutputStream("employee.dat"));
        for (int i = 0; i < staff.length; i++)
            staff[i].writeData(out);
        out.close();
    } catch (IOException e) {
        System.out.print("Error: " + e);
        System.exit(1);
    }

    try {
        RandomAccessFile in = new RandomAccessFile("employee.dat", "r");
        int count = (int) (in.length() / Employee.RECORD_SIZE);
        Employee[] newStaff = new Employee[count];

        for (int i = count - 1; i >= 0; i--) {
            newStaff[i] = new Employee();
            in.seek(i * Employee.RECORD_SIZE);
            newStaff[i].readData(in);
        }
        for (int i = 0; i < newStaff.length; i++)
            newStaff[i].print();
    } catch (IOException e) {
        System.out.print("Error: " + e);
        System.exit(1);
    }
}

---

From source file:RandomFileTest.java

public static void main(String[] args) {
    Employee[] staff = new Employee[3];

    staff[0] = new Employee("Carl Cracker", 75000, 1987, 12, 15);
    staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
    staff[2] = new Employee("Tony Tester", 40000, 1990, 3, 15);

    try {/*from ww w .  j a  va 2  s .c  om*/
        // save all employee records to the file employee.dat
        DataOutputStream out = new DataOutputStream(new FileOutputStream("employee.dat"));
        for (Employee e : staff)
            e.writeData(out);
        out.close();

        // retrieve all records into a new array
        RandomAccessFile in = new RandomAccessFile("employee.dat", "r");
        // compute the array size
        int n = (int) (in.length() / Employee.RECORD_SIZE);
        Employee[] newStaff = new Employee[n];

        // read employees in reverse order
        for (int i = n - 1; i >= 0; i--) {
            newStaff[i] = new Employee();
            in.seek(i * Employee.RECORD_SIZE);
            newStaff[i].readData(in);
        }
        in.close();

        // print the newly read employee records
        for (Employee e : newStaff)
            System.out.println(e);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

---

From source file:CreateEmployeeFile.java

public static void main(String[] args) throws Exception {
    String[] fnames = { "A", "B", "C" };

    String[] lnames = { "a", "b", "c" };

    String[] addresses = { "Box 100", "55 Street", "6 Lane" };

    byte[] ages = { 46, 59, 32 };

    double[] salaries = { 5.0, 6.0, 3.0 };

    RandomAccessFile raf = new RandomAccessFile("employee.dat", "rw");

    EmployeeRecord er = new EmployeeRecord();

    for (int i = 0; i < fnames.length; i++) {
        er.setFirstName(fnames[i]);/*w  w w . j  a v  a2  s .  com*/
        er.setLastName(lnames[i]);
        er.setAddress(addresses[i]);
        er.setAge(ages[i]);
        er.setSalary(salaries[i]);
        er.write(raf);
    }
    raf = new RandomAccessFile("employee.dat", "rw");

    er = new EmployeeRecord();

    int numRecords = (int) raf.length() / er.size();

    for (int i = 0; i < numRecords; i++) {
        er.read(raf);

        System.out.print(er.getFirstName() + " ");
        System.out.print(er.getLastName() + " ");
        System.out.print(er.getAddress() + " ");
        System.out.print(er.getAge() + " ");
        System.out.println(er.getSalary());
    }
    raf.seek(0);
    for (int i = 0; i < numRecords; i++) {
        er.read(raf);
        if (er.getAge() >= 55) {
            er.setSalary(0.0);
            raf.seek(raf.getFilePointer() - er.size());
            er.write(raf);
            raf.seek(raf.getFilePointer() - er.size());
            er.read(raf);
        }
        System.out.print(er.getFirstName() + " ");
        System.out.print(er.getLastName() + " ");
        System.out.print(er.getAddress() + " ");
        System.out.print(er.getAge() + " ");
        System.out.println(er.getSalary());
    }

}

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