Java FileReader read() Method

Example

Read a file one character at a time:

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    FileWriter myWriter = new FileWriter("filename.txt");
    myWriter.write("Hello World");
    myWriter.close();
    FileReader myReader = new FileReader("filename.txt");
    int c;
    while ((c = myReader.read()) != -1) {
      System.out.print((char) c);
    }
    myReader.close();
  }
}

Run Example »

Definition and Usage

The read() method reads one character from the file and returns it as an int (the number code of the character). Use (char) to turn the number into a character. It returns -1 when there are no more characters (the end of the file).

If you give it a char array or a CharBuffer, it reads many characters at once and stores them there. It then returns the number of characters it read, or -1 at the end of the file.

Tip: To read a file line by line, put the FileReader inside a BufferedReader and use its readLine() method.

Syntax

One of the following:

public int read()

public int read(char[] cbuf)

public int read(char[] cbuf, int off, int len)

public int read(CharBuffer target)

Parameter Values

Parameter	Description
cbuf	Optional. A `char` array to store the characters in.
off	Optional. The position in the array where the first character is stored.
len	Optional. The largest number of characters to read.
target	Optional. A `CharBuffer` (from the `java.nio` package) to store the characters in.

Technical Details

Returns:	The character as an `int` (0 to 65535), or the number of characters that were read into the array or buffer. `-1` if the end of the file is reached.
Throws:	`IOException` - if the reader is closed, or if another I/O error occurs. `IndexOutOfBoundsException` - if `off` or `len` is outside the array.