Reader close() method in Java with Examples

The close() method of Reader Class in Java is used to close the stream and release the resources that were busy in the stream, if any. This method has following results:

• If the stream is open, it closes the stream releasing the resources
• If the stream is already closed, it will have no effect.
• If any read or other similar operation is performed on the stream, after closing, it raises IOException

Syntax:

public abstract void close()

Parameters: This method does not accepts any parameters

Return Value: This method do not returns any value.

Exception: This method throws IOException if some error occurs while input output.

Below methods illustrates the working of close() method:

Program 1:

// Java program to demonstrate
// Reader close() method

import java.io.*;
import java.util.*;

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

        try {

            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Get the character
            // to be read from the stream
            int ch;

            // Read the first 5 characters
            // to this reader using read() method
            // This will put the str in the stream
            // till it is read by the reader
            for (int i = 0; i < 5; i++) {
                ch = reader.read();
                System.out.println("\nInteger value "
                                   + "of character read: "
                                   + ch);
                System.out.println("Actual "
                                   + "character read: "
                                   + (char)ch);
            }

            // Close the stream using close()
            reader.close();
            System.out.println("Stream Closed.");
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

Integer value of character read: 71
Actual character read: G

Integer value of character read: 101
Actual character read: e

Integer value of character read: 101
Actual character read: e

Integer value of character read: 107
Actual character read: k

Integer value of character read: 115
Actual character read: s
Stream Closed.

Program 2:

// Java program to demonstrate
// Reader close() method

import java.io.*;
import java.util.*;

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

        try {
            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Close the stream using close()
            reader.close();
            System.out.println("Stream Closed.");

            // Check if the Reader is
            // ready to be read using ready()
            System.out.println("Is Reader ready "
                               + "to be read"
                               + reader.ready());
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

Stream Closed.
java.io.IOException: Stream closed

Reference: https://docs.oracle.com/javase/9/docs/api/java/io/Reader.html#close–