Buffered Writer Example in Java

Introduction

Buffered Writer is a classic Java console program that demonstrates the concept with complete source code and sample output. Java I/O reads and writes bytes and characters from files, streams and the console.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

The Buffered Writer writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.

Buffered Writer Example Program

import java.io.*;

public class BufferedWriterDemo {
	public static void main(String[] args) throws IOException {
		StringWriter strwrit = null;
		BufferedWriter buffwrit = null;
		String str = "She sells sea shells on the sea shore.";
		try{
			strwrit = new StringWriter();
			buffwrit = new BufferedWriter(strwrit);
			buffwrit.write(str);
			buffwrit.flush();
			StringBuffer strbuff = strwrit.getBuffer();
			System.out.println(strbuff);
		}catch(IOException e){
			e.printStackTrace();
			}finally{
			if(strwrit!=null)
            strwrit.close();
			if(buffwrit!=null)
            buffwrit.close();
		}
	}
}

Sample Output

She sells sea shells on the sea shore.

When to use

Use this buffered writer example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. import java.io.*; imports a class used later in the program.

3. StringWriter strwrit = null; updates a variable used in the calculation or output.

4. BufferedWriter buffwrit = null; updates a variable used in the calculation or output.

5. String str = "She sells sea shells on the sea shore."; updates a variable used in the calculation or output.

6. strwrit = new StringWriter(); updates a variable used in the calculation or output.

7. buffwrit = new BufferedWriter(strwrit); updates a variable used in the calculation or output.

8. A println / print call writes text to the console — part of the sample output below.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.