Java - CharArrayReader read() method

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Description

The Java CharArrayReader read() method reads a single character. If the stream ends, it returns -1.

Declaration

Following is the declaration for java.io.CharArrayReader.read() method −

public int read()

Parameters

NA

Return Value

The method returns the character read, as an integer from the range 0 to 65535. If the stream has reached it's end the read() returns -1.

Exception

IOException − If any I/O error occurs.

Example - Using CharArrayReader read() method

The following example shows the usage of Java CharArrayReader read() method.

CharArrayReaderDemo.java

package com.tutorialspoint;

import java.io.CharArrayReader;
import java.io.IOException;

public class CharArrayReaderDemo {
   public static void main(String[] args) {      
      CharArrayReader car = null;
      char[] ch = {'H', 'E', 'L', 'L', 'O'};
      
      try {
         // create new character array reader
         car = new CharArrayReader(ch);
         
         int value = 0;
         
         // read till the end of the file
         while((value = car.read())!=-1) {
            char c = (char)value;
            
            // print the character
            System.out.print(c+" : ");
            
            // print the integer
            System.out.println(value);
         }
         
      } catch(IOException e) {
         // if I/O error occurs
         e.printStackTrace();
      } finally {
         // releases any system resources associated with the stream
         if(car!=null)
            car.close();
      }
   }
}

Output

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

H : 72
E : 69
L : 76
L : 76
O : 79

Example - Reading All Characters One by One

The following example shows the usage of Java CharArrayReader read() method.

CharArrayReaderDemo.java

package com.tutorialspoint;

import java.io.CharArrayReader;
import java.io.IOException;

public class CharArrayReaderDemo {
   public static void main(String[] args) {
      char[] data = "Hello, World!".toCharArray();

      try (CharArrayReader reader = new CharArrayReader(data)) {
         int charData;

         System.out.print("Reading characters one by one: ");
         while ((charData = reader.read()) != -1) { // Read one character at a time
            System.out.print((char) charData);    // Convert the int to char and print
         }
      } catch (IOException e) {
         System.err.println("IOException occurred: " + e.getMessage());
      }
   }
}

Output

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

Reading characters one by one: Hello, World!

Explanation

• A character array is created from the string "Hello, World!".

• A CharArrayReader is initialized with this character array.

• The read() method is used to read one character at a time until it returns -1 (end of stream).

• Each character is printed by casting the returned integer value to a char.

Example - Counting the Number of Spaces in a Character Stream

The following example shows the usage of Java CharArrayReader read() method.

CharArrayReaderDemo.java

package com.tutorialspoint;

import java.io.CharArrayReader;
import java.io.IOException;

public class CharArrayReaderDemo {
   public static void main(String[] args) {
      char[] data = "Java programming is fun!".toCharArray();

      try (CharArrayReader reader = new CharArrayReader(data)) {
         int charData;
         int spaceCount = 0;

         // Read one character at a time
         while ((charData = reader.read()) != -1) {
            if ((char) charData == ' ') { // Check if the character is a space
               spaceCount++;
            }
         }

         System.out.println("Number of spaces in the string: " + spaceCount);
      } catch (IOException e) {
         System.err.println("IOException occurred: " + e.getMessage());
      }
   }
}

Output

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

Number of spaces in the string: 3

Explanation

• The string "Java programming is fun!" is converted into a character array and passed to the CharArrayReader.

• The read() method reads one character at a time.

• Each character is checked to see if it is a space (' ').

• The count of spaces is maintained in the variable spaceCount.

• The total number of spaces is printed after the loop.

Key Points

• Use of read()−

  • The read() method reads one character at a time and returns it as an integer.

  • When the end of the stream is reached, it returns -1.

• Casting−

  • The integer returned by read() represents the character's Unicode value and must be cast to char to work with characters.

• Efficiency−

  • Reading characters one by one is less efficient compared to buffered reads, but it is useful for simple tasks like processing or analyzing individual characters.