PushbackReader read() method in Java with Examples

The read() method of PushbackReader Class in Java is used to read a single character from the stream. This method blocks the stream till:

  • It has taken some input from the stream.
  • Some IOException has occurred
  • It has reached the end of the stream while reading.

Syntax:

public int read()

Parameters: This method does not accepts any parameters



Return Value: This method returns an integer value which is the integer value read from the stream. It can range from 0 to 65535. Else it returns -1 if no character has been read.

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

Below methods illustrates the working of read() method:

Program 1:

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// Java program to demonstrate
// PushbackReader read() method
  
import java.io.*;
import java.util.*;
  
class GFG {
    public static void main(String[] args)
    {
  
        try {
            // Initializing a StringReader
            // and PushbackReader
            String s = "GeeksForGeeks";
  
            StringReader stringReader
                = new StringReader(s);
            PushbackReader pushbackReader
                = new PushbackReader(stringReader);
  
            // 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 = pushbackReader.read();
                System.out.println("\nInteger value "
                                   + "of character read: "
                                   + ch);
                System.out.println("Actual "
                                   + "character read: "
                                   + (char)ch);
            }
  
            // Close the stream using read()
            pushbackReader.close();
            System.out.println("Stream Closed.");
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

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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:

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// Java program to demonstrate
// PushbackReader read() method
  
import java.io.*;
import java.util.*;
  
class GFG {
    public static void main(String[] args)
    {
  
        try {
            // Initializing a StringReader
            // and PushbackReader
            String s = "GFG";
  
            StringReader stringReader
                = new StringReader(s);
            PushbackReader pushbackReader
                = new PushbackReader(stringReader);
  
            // Get the character
            // to be read from the stream
            int ch;
  
            // Read the first 2 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 < 2; i++) {
                ch = pushbackReader.read();
                System.out.println("\nInteger value "
                                   + "of character read: "
                                   + ch);
                System.out.println("Actual "
                                   + "character read: "
                                   + (char)ch);
            }
  
            // Close the stream
            pushbackReader.close();
            System.out.println("Stream Closed.");
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

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Output:

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

Integer value of character read: 70
Actual character read: F
Stream Closed.

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



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