Java - RandomAccessFile readChar() method

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Description

The Java RandomAccessFile readChar() method reads a character from this file. This method reads two bytes from the file, starting at the current file pointer.

Declaration

Following is the declaration for java.io.RandomAccessFile.readChar() method.

public final char readChar()

Parameters

NA

Return Value

This method returns the next two bytes of this file, interpreted as a char.

Exception

• IOException − If an I/O error occurs.

• EOFException − If this file reaches the end before reading two bytes.

Example - Usage of RandomAccessFile readChar() method

The following example shows the usage of RandomAccessFile readChar() method.

RandomAccessFileDemo.java

package com.tutorialspoint;

import java.io.RandomAccessFile;
import java.io.IOException;

public class RandomAccessFileDemo {
   public static void main(String[] args) {

      try {
         char c = 'H';
         
         // create a new RandomAccessFile with filename test
         RandomAccessFile raf = new RandomAccessFile("test.txt", "rw");

         // write something in the file
         raf.writeChar('C');

         // set the file pointer at 0 position
         raf.seek(0);

         // read char
         System.out.println(raf.readChar());

         // set the file pointer at 0 position
         raf.seek(0);

         // write a char at the start
         raf.writeChar(c);

         // set the file pointer at 0 position
         raf.seek(0);

         // read char
         System.out.println(raf.readChar());
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Output

Assuming we have a text file test.txt in current directory which has the following content. This file will be used as an input for our example program −

ABCDE

Let us compile and run the above program, this will produce the following result −

C 
H

Example - Writing and Reading Characters

The following example shows the usage of RandomAccessFile readChar() method.

RandomAccessFileDemo.java

package com.tutorialspoint;

import java.io.RandomAccessFile;
import java.io.IOException;

public class RandomAccessFileDemo {
   public static void main(String[] args) {
      try {
         RandomAccessFile raf = new RandomAccessFile("chars.dat", "rw");

         // Write characters to the file (2 bytes each)
         raf.writeChar('X');
         raf.writeChar('Y');

         // Move file pointer back to the start
         raf.seek(0);

         // Read and print characters
         char c1 = raf.readChar();
         char c2 = raf.readChar();

         System.out.println("First char: " + c1); // X
         System.out.println("Second char: " + c2); // Y

         raf.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result−

First char: X
Second char: Y

Explanation

• writeChar() writes a 16-bit Unicode character (2 bytes).

• readChar() reads 2 bytes and returns them as a char.

• You must read them in the same format they were written.

• This is ideal for reading files with fixed-size Unicode character data.

Example - Jump to a specific character position

The following example shows the usage of RandomAccessFile readChar() method.

RandomAccessFileDemo.java

package com.tutorialspoint;

import java.io.RandomAccessFile;
import java.io.IOException;

public class RandomAccessFileDemo {
   public static void main(String[] args) {
      try {
         RandomAccessFile raf = new RandomAccessFile("chars2.dat", "rw");

         // Write 3 characters
         raf.writeChar('A'); // Position 0
         raf.writeChar('B'); // Position 2
         raf.writeChar('C'); // Position 4

         // Move to second character (position 2)
         raf.seek(2);
         char secondChar = raf.readChar();

         System.out.println("Second character: " + secondChar); // B

         raf.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result−

Second character: B

Explanation

• Each character takes 2 bytes, so positions are 0, 2, 4...

• seek(2) jumps directly to the second character.

• readChar() reads from that point.

• This makes RandomAccessFile powerful for fixed-format files or random lookups in binary data.