Java.io.LineNumberInputStream Class in Java
Last Updated :
23 Jan, 2023
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:
- 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
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try {
char c;
int a;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a = geekline.read()) != - 1 )
{
c = ( char )a;
System.out.print(c);
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally
{
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
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try
{
char c;
int a, b;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a = geekline.read()) != - 1 )
{
c = ( char )a;
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)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally
{
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 can be read from the Input Stream.
Exception:
IOException : in case I/O error occurs
Implementation :
Java
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try {
char c;
int a, b;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a = geekline.read()) != - 1 )
{
c = ( char )a;
a = geekline.available();
System.out.println(c + " Bytes available : " + a);
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally
{
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
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try {
char c;
int a, b = 0 ;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a = geekline.read()) != - 1 )
{
c = ( char )a;
geekline.setLineNumber( 100 + b);
a = geekline.getLineNumber();
System.out.println(c + " Line No. Set : " + a);
b++;
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally
{
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
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try {
char c;
int a, b = 0 ;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a = geekline.read()) != - 1 )
{
c = ( char )a;
geekline.skip( 3 );
System.out.println(c);
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally {
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
import java.io.*;
public class NewClass
{
public static void main(String[] args) throws IOException
{
LineNumberInputStream geekline = null ;
FileInputStream geekinput = null ;
try {
char c;
int a;
geekinput = new FileInputStream( "ABC.txt" );
geekline = new LineNumberInputStream(geekinput);
while ((a=geekline.read())!=- 1 )
{
c = ( char )a;
System.out.print(c);
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println( "ERROR Occurs " );
}
finally
{
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
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);
System.out.println( "Char : " + ( char )geekline.read());
System.out.println( "Char : " + ( char )geekline.read());
System.out.println( "Char : " + ( char )geekline.read());
geekline.mark( 0 );
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())
{
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)
{
except.printStackTrace();
}
finally
{
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
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