PrintWriter In Java

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What is PrintWriter?

PrintWriter is a class used for writing formatted text (characters) to an output stream. It can write to various destinations, including files, console, and network sockets. It can be used in a similar way to BufferedWriter but with additional formatting capabilities.

How Does PrintWriter Work?

Without PrintWriter: When using OutputStream or even FileWriter, you might miss easy-to-use formatting methods like printing formatted text (printf(), println()).
With PrintWriter: It provides a higher-level, convenient interface for printing formatted representations of objects, writing text, and handling character data efficiently. It also handles automatic flushing of data when writing to a file or the console.

Constructors of PrintWriter

PrintWriter(Writer out)
PrintWriter(OutputStream out)
PrintWriter(File file)
PrintWriter(String fileName)
PrintWriter(Writer out, boolean autoFlush) // Enable auto flushing after println(), printf(), or format() method calls

Key Methods of PrintWriter

print(): Writes text (characters) to the output without adding a newline.
println(): Writes text followed by a newline.
printf(): Formats and writes text to the output.
flush(): Flushes the stream, ensuring all data is written to the destination.
close(): Closes the writer and releases system resources.

Code Example

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import java.io.PrintWriter;import java.io.IOException;​public class PrintWriterExample {    public static void main(String[] args) {        try (PrintWriter pw = new PrintWriter("output.txt")) {              // Create PrintWriter to write to a file            pw.println("Hello, PrintWriter!");  // Writing text with newline            pw.println("This is another line.");            pw.printf("Formatted number: %.2f", 3.14159);  // Writing formatted text        } catch (IOException e) {            e.printStackTrace();        }    }}

Explanation:

PrintWriter writes to the file output.txt.
println() writes text followed by a newline.
printf() writes formatted text, in this case, a floating-point number with two decimal places.

PrintWriter with Console (System.out)

You can also use PrintWriter with System.out to provide more control over writing to the console.

Code Example

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import java.io.PrintWriter;​public class ConsolePrintWriterExample {    public static void main(String[] args) {        PrintWriter pw = new PrintWriter(System.out, true);  // Auto-flush enabled​        pw.println("Hello from PrintWriter to the console!");  // Print with a newline        pw.printf("Formatted string: %s%n", "Java I/O");  // Print formatted text    }}

Explanation:

PrintWriter is used to write text to the console (standard output, System.out).
Auto-flushing is enabled, meaning the buffer is automatically flushed after println() and printf() calls.

Differences Between BufferedWriter and PrintWriter

Feature	BufferedWriter	PrintWriter
Purpose	Used for efficient character output	Used for formatted character output
Output Destination	Writer or file	Writer, OutputStream, or file
Formatted Output	Does not support formatted output	Supports `printf()`, `println()`, `format()`
Auto-flush Feature	No auto-flush option	Supports auto-flush for certain methods
Use Case	General character-based output to a file	Convenient for formatted output, especially with streams, files, or consoles