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.