Java PrintWriter With Example
In this article, we will look at one of the important classes of Java version 7, PrintWriter. Let's get started.
Introduction
The PrintWriter class in Java was released in Java 7, as a subclass of the Writer class. This class is basically used for printing the formatted representations of objects to a text-output stream.
The PrintWriter class implements all the methods of the PrintStream class. However, this class does not have any methods that are used for writing raw bytes.
Note: the PrintWriter class is also used for write a file in Java.
The PrintWriter class has some differences when compared to the PrintStream class. In the PrintStream class, when automatic flushing is enabled, output will be sent when the newline character is the output.
But, in the PrintWriter class, when automatic flushing is enabled, ouput will be printed when the following methods are invoked: println, printf, etc.
Basically, the above-mentioned methods use the platform's notion of a line separator, not a new-line character. One important thing about the PrintWriter class is that it never throws any I/O exceptions. However, its constructor does in case of an error.
This class has a method checkError(), which can be invoked by the client to check whether any error is occurred.
You may also like: Java 8 (A Comprehensive Look): Part 1.1 - Lambdas Under the Hood
Methods of PrintWriter Class
| Method | Description |
|---|---|
| void println(boolean x) | This is used to print the boolean value provided in the method parameter. |
| void println(char[] x) | This method is used to print an array of characters provided in the parameter. |
| void println(int x) | This is used for printing an integer value. |
| PrintWriter append(char c) | This method appends the specified character to the writer. |
| PrintWriter append(CharSequence ch) | This method appends the specified character sequence to the writer. |
| PrintWriter append(CharSequence ch, int start, int end) | This method is used for appending a subsequence of specified character to the writer. |
| boolean checkError() | This method is used to flushes the stream and check its error state. |
| protected void setError() | This method indicates that an error occurs. |
| protected void clearError() | This method is used to clear all the errors. |
| PrintWriter format(String format, Object... args) | This method is used for writing a formatted string to the writer using specified arguments and format string. |
| void print(Object obj) | This method simply prints the object. |
| void flush() | This method flushes the stream. |
| void close() | This is to close the stream. |
PrintWriter Example
package com.dzone;
import java.io.File;
import java.io.PrintWriter;
public class PrintWriterTest {
public static void main(String[] args) throws Exception {
PrintWriter writerObj = new PrintWriter(System.out);
writerObj.write("Dzone article");
writerObj.flush();
writerObj.close();
PrintWriter writerObj1 =null;
writerObj1 = new PrintWriter(new File("C:\\main.txt"));
writerObj1.write("Dzone Line number 2");
writerObj1.flush();
writerObj1.close();
}
}
Further Reading
Opinions expressed by DZone contributors are their own.