File Output Stream in Java

FileOutputStream is used to create a file and write data into it.The stream would create a file, if it doesn't already exist, before opening it for output. Here are two constructors which can be used to create a FileOutputStream object.

Following constructor takes a file name as a string to create an input stream object to write the file:
OutputStream f = new FileOutputStream("C:/java/hello")

Following constructor takes a file object to create an output stream object to write the file. First we create a file object using File() method as follows:
File f = new File("C:/java/hello");
OutputStream f = new FileOutputStream(f);

DataOutputStream
The DataOutputStream stream let you write the primitives to an output source. Following is the constructor to create an DataOutputStream.
DataOutputStream out = DataOutputStream(OutputStream out);

Example:
Following is the example to demonstrate DataInputStream and DataInputStream. This example reads 5 lines given in a file test.txt and convert those lines into capital letters and finally copies them into another file test1.txt.
import java.io.*;
public class Test{
public static void main(String args[])throws IOException{
DataInputStream d = new DataInputStream(new
FileInputStream("test.txt"));
DataOutputStream out = new DataOutputStream(new
FileOutputStream("test1.txt"));
String count;
while((count = d.readLine()) != null){
String u = count.toUpperCase();
System.out.println(u);
out.writeBytes(u + " ,");
}
d.close();
out.close();
}
}