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Java OutputStreamWriter flush() Method with Example

OutputStreamWriter Class flush() method: Here, we are going to learn about the flush() method of OutputStreamWriter Class with its syntax and example.
Submitted by Preeti Jain, on April 16, 2020

OutputStreamWriter Class flush() method

• flush() method is available in java.io package.
• flush() method is used to flush this stream.
• flush() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• flush() method may throw an exception at the time of flushing the stream.
  IOException: This exception may throw when getting any input/output error while performing.

Syntax:

    public void flush();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of the method is void, it returns nothing.

Example:

// Java program to demonstrate the example 
// of void flush() method 
// of OutputStreamWriter

import java.io.*;

public class FlushOfOSW {
 public static void main(String[] args) throws Exception {
  OutputStream os_stm = null;
  OutputStreamWriter osw_stm = null;
  InputStream is_stm = null;
  int val = 65;
  try {

   // Instantiates FileOutputStream and 
   // FileInputStream and OutputStreamWriter
   os_stm = new FileOutputStream("D:\\includehelp.txt");
   osw_stm = new OutputStreamWriter(os_stm);

   // Loop to write byte to the stream
   for (int i = 0; i < 3; ++i) {
    osw_stm.write(val);
    val++;
   }

   // By using flush() method is to
   // flush the stream
   osw_stm.flush();
   System.out.println("Stream Flushed...");

   is_stm = new FileInputStream("D:\\includehelp.txt");

   // Loop to read byte from the stream
   for (int i = 0; i < 3; ++i) {
    char ch = (char) is_stm.read();
    System.out.println("ch: " + ch);

   }

   osw_stm.close();
   System.out.println("Stream Closed Successfully....");

  } catch (Exception ex) {
   System.out.println(ex.toString());
  } finally {
   // with the help of this block is to
   // free all necessary resources linked
   // with the stream
   if (is_stm != null) {
    is_stm.close();
    if (os_stm != null) {
     os_stm.close();
    }
   }
  }
 }
}

Output

Stream Flushed...
ch: A
ch: B
ch: C
Stream Closed Successfully....