PushbackReader skip(long) in Java

skip(long): This method is available in the java.io.PushbackReader class of Java.

Syntax:

long java.io.PushbackReader.skip(long n) throws IOException

This method takes one argument. This method skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.

Parameters: One parameter is required for this method.

n: The number of characters to skip.

Returns: The number of characters actually skipped.

Throws:

1. IllegalArgumentException - If n is negative.

2. IOException - If an I/O error occurs

Approach 1: When no exception

Java

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

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

        Reader in = new StringReader("HELLO");
        PushbackReader pushbackReader = new PushbackReader(in);

        long n = 100L;

        System.out.println(pushbackReader.skip(n));
        pushbackReader.close();
    }
}

Output:

5


Approach 2: IllegalArgumentException 

Java

package com.PushbackReader;

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

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

        Reader in = new StringReader("HELLO");
        PushbackReader pushbackReader = new PushbackReader(in);

        long n = -1;

        System.out.println(pushbackReader.skip(n));
        pushbackReader.close();
    }
}

Output:

Exception in thread "main" java.lang.IllegalArgumentException: skip value is negative at java.base/java.io.PushbackReader.skip(PushbackReader.java:269) at com.PushbackReader.PushbackReaderskip.main(PushbackReaderskip.java:16)


Approach 3: IOException

Java

package com.PushbackReader;

import java.io.IOException;
import java.io.PipedReader;
import java.io.PushbackReader;
import java.io.Reader;

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

        Reader in = new PipedReader();
        PushbackReader pushbackReader = new PushbackReader(in);

        long n = 100L;

        System.out.println(pushbackReader.skip(n));
        pushbackReader.close();
    }
}

Output:

Exception in thread "main" java.io.IOException: Pipe not connected at java.base/java.io.PipedReader.read(PipedReader.java:293) at java.base/java.io.Reader.skip(Reader.java:277) at java.base/java.io.FilterReader.skip(FilterReader.java:84) at java.base/java.io.PushbackReader.skip(PushbackReader.java:282) at com.PushbackReader.PushbackReaderskip.main(PushbackReaderskip.java:16)


Some other methods of PushbackReader

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, which it does not.

PushbackReader(Reader)This method creates a new pushback reader with a one-character pushback buffer.

PushbackReader(Reader, int)This method creates a new pushback reader with a pushback buffer of the given size.

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.

skip(long)This method skips characters

unread(char[])This method pushes back an array of characters by copying it to the front of the pushback buffer.

unread(int)This method pushes back a single character by copying it to the front of the pushback buffer.

unread(char[], int, int) This method pushes back a portion of an array of characters by copying it to the front of the pushback buffer.

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