CharArrayReader read(char[], int, int) in Java

read(char[], int, int): This method is available in the java.io.CharArrayReader class of Java.

Syntax:

int java.io.CharArrayReader.read(char[] b, int off, int len) throws IOException

This method takes three arguments. This method reads characters into a portion of an array.

Parameters: Three parameters are required for this method.

b: Destination buffer.

off: Offset at which to start storing characters.

len: Maximum number of characters to read.

Returns: The actual number of characters read, or -1 if the end of the stream has been reached.

Throws:

1. IOException - If an I/O error occurs.

2. IndexOutOfBoundsException - If off is negative, or len is negative, or len is greater than cbuf.length - off

Approach 1: When no exception

Java

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

public class CharArrayReaderread2 {

    public static void main(String[] args) throws IOException {
        char buf[] = { 'a', 'b', 'c', 'd' };
        CharArrayReader charArrayReader = 
                        new CharArrayReader(buf);

        char cbuf[] = { 'a', 'b' };

        int off = 0, len = 2;

        System.out.println(charArrayReader.read(cbuf, off, len));
        charArrayReader.close();

    }
}

Output:

2

Approach 2: IndexOutOfBoundsException 

Java

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

public class CharArrayReaderread2 {

    public static void main(String[] args) throws IOException {
        char buf[] = { 'a', 'b', 'c', 'd' };
        CharArrayReader charArrayReader =
                    new CharArrayReader(buf);

        char cbuf[] = { 'a', 'b' };

        int off = -1, len = 2;

        System.out.println(charArrayReader.read(cbuf, off, len));
        charArrayReader.close();

    }
}

Output:

Exception in thread "main" java.lang.IndexOutOfBoundsException
	at java.base/java.io.CharArrayReader.read(CharArrayReader.java:126)