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

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

Syntax:

int java.io.StringReader.read(char[] cbuf, 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.

cbuf: Destination buffer.

off: Offset at which to start writing characters.

len: Maximum number of characters to read.

Returns: The number of characters reads, 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.

3. NullPointerException - If cbuf is null.

Approach 1: When no exception

Java

import java.io.IOException;
import java.io.StringReader;

public class StringReaderread2 {
    public static void main(String[] args) {

        String s = "HELLO JAVA";
        StringReader stringReader = new StringReader(s);

        char cbuf[] = { 'a', 'b', 'c', 'd', 'e', 'f' };

        int off = 0, len = 4;
        try {
            System.out.println(stringReader.read(cbuf, off, len));
        } catch (IOException e) {
            System.out.println("IOException occurs");

        } catch (IndexOutOfBoundsException e) {
            System.out.println("IndexOutOfBoundsException occurs");

        } catch (NullPointerException e) {
            System.out.println("NullPointerException occurs");

        }
    }
}

Output:

4

Approach 2: IOException

Java

import java.io.IOException;
import java.io.StringReader;

public class StringReaderread2 {
    public static void main(String[] args) {

        String s = "HELLO JAVA";
        StringReader stringReader = new StringReader(s);

        char cbuf[] = { 'a', 'b', 'c', 'd', 'e', 'f' };

        stringReader.close();
        int off = 0, len = 4;
        try {
            System.out.println(stringReader.read(cbuf, off, len));
        } catch (IOException e) {
            System.out.println("IOException occurs");

        } catch (IndexOutOfBoundsException e) {
            System.out.println("IndexOutOfBoundsException occurs");

        } catch (NullPointerException e) {
            System.out.println("NullPointerException occurs");

        }
    }
}

Output:

IOException occurs

Approach 3: IndexOutOfBoundsException 

Java

import java.io.IOException;
import java.io.StringReader;

public class StringReaderread2 {
    public static void main(String[] args) {

        String s = "HELLO JAVA";
        StringReader stringReader = new StringReader(s);

        char cbuf[] = { 'a', 'b', 'c', 'd', 'e', 'f' };

        int off = 0, len = 14;
        try {
            System.out.println(stringReader.read(cbuf, off, len));
        } catch (IOException e) {
            System.out.println("IOException occurs");

        } catch (IndexOutOfBoundsException e) {
            System.out.println("IndexOutOfBoundsException occurs");

        } catch (NullPointerException e) {
            System.out.println("NullPointerException occurs");

        }
    }
}

Output:

IndexOutOfBoundsException occurs

Approach 4: NullPointerException 

Java

import java.io.IOException;
import java.io.StringReader;

public class StringReaderread2 {
    public static void main(String[] args) {

        String s = "HELLO JAVA";
        StringReader stringReader = new StringReader(s);

        char cbuf[] = null;

        int off = 0, len = 4;
        try {
            System.out.println(stringReader.read(cbuf, off, len));
        } catch (IOException e) {
            System.out.println("IOException occurs");

        } catch (IndexOutOfBoundsException e) {
            System.out.println("IndexOutOfBoundsException occurs");

        } catch (NullPointerException e) {
            System.out.println("NullPointerException occurs");

        }
    }
}

Output:

NullPointerException occurs

Some other methods of StringReader

close(): This method closes the stream and releases any system resources associated with it.

mark(int): This method marks the present position in the stream. Subsequent calls to reset() will reposition the stream to this point.

markSupported(): This method tells whether this stream supports the mark() operation, which it does.

read(): This method reads a single character.

read(char[], int, int): This method reads characters into a portion of an array.

ready(): This method tells whether this stream is ready to be read.

reset(): This method resets the stream to the most recent mark, or to the beginning of the string if it has never been marked.

skip(long): This method skips the specified number of characters in the stream.

StringReader(String): This method creates a new string reader.