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Java.io.LineNumberInputStream Class in Java

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  • Last Updated : 12 Oct, 2021
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java.io.LineNumberInputStream class is simply an extension of input stream providing a extra facility to keep the record of current line number. 

Line is a sequence of bytes ending with : ‘\r’ i.e. a carriage return character or a newline character : ‘\n’, or a linefeed character following the carriage return character.

Declaration :  

public class LineNumberInputStream
   extends Reader

Constructors :  

LineNumberInputStream(InputStream in) : 
Constructs a newline no. stream that reads 
it's input from the specified Input Stream.

Methods:  

LineNumberInputStream Class

  • read() : java.io.LineNumberInputStream.read() reads next byte of data from input stream. It returns int value representing the bytes in the range of ‘0 – 255’. It returns ‘-1’ to indicate end of Input Stream. 
    Syntax : 
public int read()
Parameters : 
-------
Return : 
int value representing the bytes in the range of '0 - 255'.
return -1, indicating end of Input Stream.
Exception: 
IOException : in case I/O error occurs

Implementation : 

Java




// Java program illustrating the working of read() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            // read() method returning Bytes of Input Stream as integer
            // '-1' indicating to read till end Of Input Stream
            while((a = geekline.read()) != -1)
            {
                // Since read() method returns Integer value
                // So, we convert each integer value to char
                c = (char)a;
                System.out.print(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
       {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

Hello
Geeks.
Explaining 
read() method

Output : 

Hello
Geeks.
Explaining 
read() method
  • getLineNumber() : java.io.LineNumberInputStream.getLineNumber() returns number of current line. 
    Syntax : 
 public int getLineNumber()
Parameters : 
-------
Return : 
no. of current line

Implementation : 

Java




// Java program illustrating the working of getLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try
           {
            char c;
            int a, b;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
                 
                // Use of getLineNumber() : to print line no.
                a = geekline.getLineNumber();
                System.out.println(" At line : " + a);
                System.out.print(c);
 
            }
            a = geekline.getLineNumber();
            System.out.println(" at line: " + a);
 
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

no. of
lines

Output : 

 At line : 0
n At line : 0
o At line : 0
. At line : 0
  At line : 0
o At line : 0
f At line : 1

 At line : 1
l At line : 1
i At line : 1
n At line : 1
e At line : 1
s at line: 1
  • available() : java.io.LineNumberInputStream.available() returns the number of bytes that can be read from the Input Stream without blocking. 
    Syntax : 
public int available()
Parameters : 
-------
Return : 
returns the no. of bytes that an be read from the Input Stream.
Exception: 
IOException : in case I/O error occurs

Implementation : 

Java




// Java program illustrating the working of available() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
              // So, we convert each integer value to char
                c = (char)a;
 
              // Use of available method : return no. of bytes that can be read
                a = geekline.available();
                System.out.println(c + " Bytes available : " + a);
 
            }
 
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

available

Output : 

a Bytes available : 4
v Bytes available : 3
a Bytes available : 3
i Bytes available : 2
l Bytes available : 2
a Bytes available : 1
b Bytes available : 1
l Bytes available : 0
e Bytes available : 0
  • setLineNumber() : java.io.LineNumberInputStream.setLineNumber(int arg) assigns line number to the argument we want. 
    Syntax : 
public void setLineNumber(int arg)
Parameters : 
arg : line number to assign
Return : 
void
Exception: 
-----

Implementation : 

Java




// Java program illustrating the working of setLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b = 0;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
                 
                // Use of setLineNumber() : to set the line no.
                geekline.setLineNumber(100 + b);
 
                // getLineNumber() : returning the current line no.
                a = geekline.getLineNumber();
                System.out.println(c + " Line No. Set : " + a);
                b++;
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

LineNumber

Output : 

L Line No. Set : 100
i Line No. Set : 101
n Line No. Set : 102
e Line No. Set : 103
N Line No. Set : 104
u Line No. Set : 105
m Line No. Set : 106
b Line No. Set : 107
e Line No. Set : 108
r Line No. Set : 109
  • skip() : java.io.LineNumberInputStream.skip(long arg) skips and discards ‘arg’ bytes from Input Stream data. The skip method of LineNumberInputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. 
    Syntax : 
public long skip(long arg)
Parameters : 
arg : no. of bytes of Input Stream data to skip.
Return : 
no. of bytes to be skipped
Exception: 
IOException : in case I/O error occurs

Implementation : 

Java




// Java program illustrating the working of setLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b = 0;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
 
                // skip() : to skip and discard 'arg' bytes
                // Here skip() will skip and discard 3 bytes.
                geekline.skip(3);
                System.out.println(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally{
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

Program
Explaining
Skip() method

Output :” 

P
r
E
a
n
k
)
t
  • read() : java.io.LineNumberInputStream.read(byte[] buffer, int offset, int maxlen) reads up to ‘maxlen’ bytes from Input Stream into bytes. 
    Syntax : 
public int read(byte[] buffer, int offset, int maxlen)
Parameters : 
buffer : buffer whose data to read
offset : starting offset of the data
maxlen : max. no. of bytes to read
Return : 
total no. of bytes, else return -1 if End of Input Stream is identified
Exception: 
IOException : in case I/O error occurs

Implementation : 

Java




// Java program illustrating the working of read() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            // read() method returning Bytes of Input Stream as integer
            // '-1' indicating to read till end Of Input Stream
            while((a=geekline.read())!=-1)
            {
                // Since read() method returns Integer value
                // So, we convert each integer value to char
                c = (char)a;
                System.out.print(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
       {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
The following Java Code won’t run here as we can’t access any file on online IDE. 
So, copy the program to your system and run it there.

The ABC.txt file used in the program contains : 

Read() method

what the method does is offset = r and maxlen = 5… so —i.e. 3 offset, then 5 bytes i.e. Read(, then again offset, so — 
Output : 

The number of char read: 5

---Read(--
  • mark() : Java.io.LineNumberInputStream.mark(int arg) marks the current position of the input stream. It sets readlimit i.e. maximum number of bytes that can be read before mark position becomes invalid. 
    Syntax :
public void mark(int arg)
Parameters :
arg : integer specifying the read limit of the input Stream
Return : 
void
  • reset() : Java.io.LineNumberInputStream.reset() is invoked by mark() method. It re-positions the input stream to the marked position. 
    Syntax :
public void reset()
Parameters :
----
Return : 
void
Exception :
->  IOException : If I/O error occurs.

Java Program explaining LineNumberInputStream Class methods : reset() and mark() 

Java




// Java program illustrating the working of LineNumberInputStream method
// mark() and reset()
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws Exception
    {
 
        LineNumberInputStream geekline = null;
        FileInputStream geek = null;
        try{
 
            geek = new FileInputStream("GEEKS.txt");
            geekline = new LineNumberInputStream(geek);
 
            // read() method : reading and printing Characters one by one
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
 
            // mark() : read limiting the 'geek' input stream
            geekline.mark(0);
 
            // skip() : it results in reading of 'e' in G'e'eeks
            geekline.skip(1);
            System.out.println("skip() method comes to play");
            System.out.println("mark() method comes to play");
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
 
            boolean check = geekline.markSupported();
            if(geekline.markSupported())
            {
                // reset() method : repositioning the stream to marked positions.
                geekline.reset();
                System.out.println("reset() invoked");
                System.out.println("Char : " + (char)geekline.read());
                System.out.println("Char : " + (char)geekline.read());
            }
            else
            {
                System.out.println("reset() method not supported.");
            }
 
            System.out.println("geekline.markSupported() supported reset() : "
                                                        + check);
 
        }
        catch(Exception except)
        {
 
            // in case of I/O error
            except.printStackTrace();
        }
        finally
        {
            // releasing the resources back to the GarbageCollector when closes
            if(geek != null)
                geek.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

Note : 
This code won’t run on online IDE as no such file is present here. 
You can run this code on your System to check the working. 

ABC.txt file used in the code has 

HelloGeeks

Output : 

Char : H
Char : e
Char : l
skip() method comes to play
mark() method comes to play
Char : o
Char : G
Char : e
reset() method not supported.
geekline.markSupported() supported reset() : false

This article is contributed by Mohit Gupta 🙂. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks. 
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 


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