Java Writer Class
What is Java Writer Class?
The Java Writer class is a subclass of the abstract class Writer, which provides a way to write characters to a file or another output stream.
The Writer class is a character stream class, which means it reads and writes Unicode characters, one at a time.The Writer class provides a set of methods that allow you to write characters to the stream
To understand the Java Writer Class, Read the Complete Article.
Sub Class of Writer:
The Java Writer class is an abstract class and cannot be instantiated. Instead, you can create instances of its subclasses to write characters to various types of output streams.
Here are some common subclasses of the Java Writer class:
- FileWriter: Writes characters to a file. It inherits the methods of the Writer class and provides additional methods for working with files.
- StringWriter: Writes characters to a string. It is useful for capturing output that would normally be written to the console or a file.
- BufferedWriter: Adds buffering to an existing Writer instance, which can improve performance by reducing the number of write operations to the underlying stream.
- CharArrayWriter: Writes characters to an in-memory buffer, which can be accessed as a character array.
- PrintWriter: Provides methods for writing formatted text to an output stream.
- OutputStreamWriter: Converts a byte-oriented OutputStream into a character-oriented Writer. This is useful for writing characters to streams that are designed to handle only bytes, such as network sockets or file streams.
Create a writer:
Choose a subclass of Writer that matches your needs. For example, if you want to write characters to a file, you can use the FileWriter class.
Create an instance of the chosen Writer subclass by calling its constructor and passing in the appropriate arguments.
Use the write() method of the Writer instance to write characters to the output stream.
Once you have finished writing characters to the output stream, it is important to call the close() method on the Writer instance to release any resources associated with it.
Methods of Writer:
- write(char[] cbuf) - writes an array of characters to the output stream.
- write(char[] cbuf, int off, int len) - writes a portion of an array of characters to the output stream, starting from the offset off and writing len characters.
- write(int c) - writes a single character to the output stream. write(String str) - writes a string to the output stream.
- write(String str, int off, int len) - writes a portion of a string to the output stream, starting from the offset off and writing len characters.
- flush() - flushes the output stream, ensuring that any buffered characters are written to the underlying stream.
- close() - closes the output stream and releases any resources associated with it
Let’s look at the Java Writer Class Using FileWriter Method to perform certain operations.
Example 1: Java Program to Writer Using FileWriter Method
Run
import java.io.*;
public class Main
{
public static void main (String[]args)
{
try
{
// Create a FileWriter object with the name of the file to write
FileWriter writer = new FileWriter ("output.txt");
// Write a string to the file
writer.write ("Hello, World!");
// Close the FileWriter object to release any resources held by it
writer.close ();
System.out.println ("Successfully wrote to the file.");
} catch (IOException e)
{
System.out.println ("An error occurred.");
e.printStackTrace ();
}
}
}
Output
Hello, World!
Explanation:
In this program, we create a FileWriter object by passing the name of the file we want to write to ("output.txt") as an argument to the constructor.
We then call the write() method on the FileWriter object to write the string "Hello, World!" to the file.
Finally, we close the FileWriter object using the close() method to release any resources held by it.
When you run this program, it will create a file named "output.txt" in the same directory as the Java file, and write the string "Hello, World!" to it.
Example 2 : Java HashMap getOrDefault() Method
Run
import java.io.FileWriter;
import java.io.IOException;
public class Main {
public static void main(String[] args) {
// Specify the file path and name
String filePath = "example.txt";
// Use try-with-resources to ensure the FileWriter is closed properly
try (FileWriter writer = new FileWriter(filePath)) {
// Write some data to the file
writer.write("Hello, world!");
writer.write(System.lineSeparator());
writer.write("This is an example of using FileWriter to write data to a file.");
} catch (IOException e) {
System.err.println("An error occurred while writing to the file: " + e.getMessage());
}
}
}
Output
Hello, world! This is an example of using FileWriter to write data to a file.
Explanation:
In this example, the FileWriter is created and opened for writing to the file specified by filePath.
The write method is then called to write some data to the file, including a newline character using System.lineSeparator().
Finally, the FileWriter is closed automatically by the try-with-resources block.
If an error occurs while writing to the file, such as if the file cannot be created or written to, an IOException will be thrown and the error message will be printed to the console.
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