Reader ready() in Java

ready(): This method is available in the java.io.Reader class of Java.

Syntax:

boolean java.io.Reader.ready() throws IOException

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

Parameters: NA

Returns: True if the next read() is guaranteed not to block for input, false otherwise.

Note that returning false does not guarantee that the next read will block.

Throws:

1. IOException - If an I/O error occurs

Approach 1: When no exception

Java

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

public class Readerready {
    public static void main(String[] args) throws IOException {

        Reader reader = new StringReader("HELLO");

        System.out.println(reader.ready());
        reader.close();

    }
}

Output:

true


Approach 2: IOException 

Java

package com.Reader;

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

public class Readerready {
    public static void main(String[] args) throws IOException {

        Reader reader = new StringReader("HELLO");

        reader.close();
        System.out.println(reader.ready());

    }
}

Output:

Exception in thread "main" java.io.IOException: Stream closed at java.base/java.io.StringReader.ensureOpen(StringReader.java:56) at java.base/java.io.StringReader.ready(StringReader.java:145) at com.Reader.Readerready.main(Readerready.java:13)


Some other methods of Reader

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.

markSupported()This method tells whether this stream supports the mark() operation. 

Reader.nullReader()This method returns a new Reader that reads no characters.

read()This method reads a single character.

read(char[])This method reads characters into an array.

read(CharBuffer)This method attempts to read characters into the specified character buffer.

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.

skip(long)This method skips characters.

transferTo(Writer)This method reads all characters from this reader and writes the characters to the given writer in the order that they are read.

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