Java IO Tutorial - Java DataOutputStream

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DataOutputStream can write Java primitive data type values to an output stream.

The DataOutputStream class contains a write method to write a data type. It supports writing a string to an output stream using the writeUTF(String text) method.

To write Java primitive data type values to a file named primitives.dat, we construct an object of DataOutputStream as follows:

DataOutputStream dos  = new DataOutputStream(new FileOutputStream("primitives.dat"));

Example

The following code writes an int value, a double value, a boolean value, and a string to a file named primitives.dat.

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
/*  w w  w. j  a  v  a 2 s  .co  m*/
public class Main {
  public static void main(String[] args) {
    String destFile = "primitives.dat";

    try (DataOutputStream dos = new DataOutputStream(new FileOutputStream(
        destFile))) {
      dos.writeInt(765);
      dos.writeDouble(6789.50);
      dos.writeBoolean(true);
      dos.writeUTF("Java Input/Output  is cool!");

      dos.flush();

      System.out.println("Data has  been  written to "
          + (new File(destFile)).getAbsolutePath());
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

The code above generates the following result.

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