File I/O using character streams

Using character streams for file I/O operations in Java is mainly useful for manipulating Unicode text, unlike byte-based streams. Classes like FileReader and FileWriter facilitate this operation with text files.

Using FileWriter

The FileWriter class allows you to create a Writer object to write to files. Its main constructors are:

FileWriter(String nomeArquivo) throws IOException
FileWriter(String nomeArquivo, boolean incluir) throws IOException

• filename: Indicates the full path of the file.
• include: Defines whether the writing will be added to the end of the file (true) or whether it will overwrite the existing file (false).

Below is an example of a simple program that reads lines of text from the keyboard and writes them to a file called "test.txt". Reading continues until the user types "stop".

import java.io.*;

class KtoD {
  public static void main(String args[]) {
    String str;
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    System.out.println("Enter text ('stop' to quit).");

    try (FileWriter fw = new FileWriter("test.txt")) {
      do {
        System.out.print(": ");
        str = br.readLine();
        if (str.compareTo("stop") == 0) break;
        str = str + "\r\n"; // adiciona nova linha
        fw.write(str);
      } while (str.compareTo("stop") != 0);
    } catch(IOException exc) {
      System.out.println("I/O Error: " + exc);
    }
  }
}

In this example:

• BufferedReader reads lines of text from the console.
• FileWriter writes the text to the file "test.txt", adding a new line after each entry.
• Stop condition: When user enters "stop", recording stops.

Using FileWriter with BufferedReader simplifies writing text and manipulating data in files, especially in continuous and internationalized text operations.

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