FilterOutputStream

FilterOutputStream is the wrapper class for the Java OutputStream Class and it provides special features and improves the performance in writing to a file. FilterOutputStream overrides all the methods of OutputStream.

The subclasses of FilterOutputStream are Java BufferedOutputStream - BufferedOutputStream In Java, DataOutputStream, Java PrintStream Class
Constructor :

Constructor	Description
`protected FilterInputStream(InputStream in)`	Creates a `FilterInputStream` object for the passed `Inputstream` Object

Important Methods :

Method	Description
`void write(int b)`	Writes the specified byte to this output stream.
`void flush()`	Flushes the output stream and forces any buffered output bytes to be written out to the stream.
`void close()`	Closes this output stream and releases any system resources associated with the stream.

FilterOutputStreamDemo

CODE

Try it Online

import java.io.*;

class FilterOutputStreamDemo
{
    public static void main(String arg[])
    {
        File f = new File("E:/JavaPrograms/FolderOne/fileOne.java"); // LINE A
        if(f.exists())
            System.out.println("File exists.");
        else
            System.out.println("File not found.");
        FilterOutputStream fos = new FilterOutputStream(new FileOutputStream(f)); // LINE B
                                                                    
        
        String s = "I love programming.";
        byte[] b = s.getBytes(); // LINE C
        fos.write(b); // LINE D
        fos.close(); // LINE E
    
    }
}

OUTPUT

File exists.
I love programming.

DESCRIPTION

At LINE A we are declaring the path of the file. At LINE B we are creating the FilterOutputStream for FileOutputStream object so that to improve the performance. At LINE C we are converting the string to byte array. At LINE D we are writing into File At LINE E we are closing the Stream object.

THINGS TO TRY

Now write I LOVE JAVA to file.

Comment the LINE E and run the program. See the file to check the data. No data will be present since the Stream is not closed the file no data will be shown.

Try it Online

Rest Of Methods :

Method	Description
`void write(byte[] b)`	Writes `b.length` bytes to the output stream.
`void write(byte[] b, int off, int len)`	Writes `len` bytes from the specified byte array starting at offset `off` to the output stream.