Java BufferedReader Class
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java.io.BufferedReader Class
BufferedReader Class in Java
The Java BufferedReader class reads text from a character input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines. To perform console input use a byte stream. Today, using a byte stream to read console input is still acceptable.
For commercial applications, the preferred method of reading console input is to use a character oriented stream. This makes your program easier to internationalize and maintain. In Java, console input is accomplished by reading from System.in. To obtain a character based stream that is attached to the console, wrap System.in in a BufferedReader object. BufferedReader supports a buffered input stream.
System.in refers to an object of type InputStream, it can be used for inputStream.
In this tutorial you can learn about java io BufferedReader class. And how to use java io BufferedReader class examples.
What is Java BufferedReader Class ?
The Java BufferedReader class is used to read the stream of characters from the specified source.
How to read the characters from the console
The following program shows how to get input from console using java.
/* How to read the characters from the console Example
Save with file name BufferedReaderExample.java */
import java.io.*;
public class BufferedReaderExample
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// WE SHOULD USE try-catch BECAUSE MOST OF THE
// JAVA I/O CLASES THROWS IOException
try
{
// DECLARE THE PREMITIVE DATA TYPE char
char c;
ir = new InputStreamReader(System.in);
br = new BufferedReader(ir);
System.out.println("Enter Characters, q to Quit : ");
do
{
c = (char) br.read();
System.out.println("Char : "+c);
}while(c != 'q');
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
The above program output may look a little different from what you expected because System.in is line buffered, by default. This means that no input is actually passed to the program until you press ENTER. As you can guess, this does not make read() particularly valuable for interactive console input.
How to read the lines of text from the console
The following program demonstrates BufferedReader and the readLine() method; the program reads and displays lines of text until you enter the word "stop".
/* How to read the lines of text from the console Example
Save with file name BufferedReaderExample2.java */
import java.io.*;
public class BufferedReaderExample2
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
try
{
String str;
ir = new InputStreamReader(System.in);
br = new BufferedReader(ir);
System.out.println("Enter some lines of text, stop to Quit : ");
do
{
str = br.readLine();
System.out.println("Line Text is : "+str);
}while(!str.equals("stop"));
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
How to read the text from file using Java BufferedReader
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/* How to read the text from file using Java BufferedReader Example
Save with file name BufferedReaderExample3.java */
import java.io.*;
public class BufferedReaderExample3
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// FileInputStream DECLARATION
FileInputStream fis = null;
try
{
int ch=0;
fis = new FileInputStream("BufferedReaderExample3.java");
ir = new InputStreamReader(fis);
br = new BufferedReader(ir);
while((ch = br.read()) != -1)
{
// CONVERT byte TO char
System.out.print( (char) ch);
}
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
How to read total bytes from file into array using Java BufferedReader
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/* How to read total bytes from file into array
using java BufferedReader Example
Save with file name BufferedReaderExample4.java */
import java.io.*;
public class BufferedReaderExample4
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// FileInputStream DECLARATION
FileInputStream fis = null;
// ARRAY TO READ BYTES
char charbuff[] = null;
try
{
fis = new FileInputStream("BufferedReaderExample4.java");
ir = new InputStreamReader(fis);
br = new BufferedReader(ir);
// GET THE AVAILABLE BYTES FROM InputReader AND CREATES ARRAY
charbuff = new char[fis.available()];
// READ TOTAL BYTES FROM FILE
br.read(charbuff, 0,fis.available());
// PRINT CHARACTERS FROM ARRAY
for(int j=0;j<charbuff.length;j++)
{
// CONVERT byte TO char
System.out.print( (char) charbuff[j]);
}
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
// RELEASE ARRAY MEMORY
charbuff = null;
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
How to read text line by line from file using Java BufferedReader
/* How to read text line by line
from file using java BufferedReader Example
Save with file name BufferedReaderExample5.java */
import java.io.*;
public class BufferedReaderExample5
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// FileInputStream DECLARATION
FileInputStream fis = null;
// String TO READ LINE FROM FILE
String line = null;
try
{
fis = new FileInputStream("BufferedReaderExample5.java");
ir = new InputStreamReader(fis);
br = new BufferedReader(ir);
// GET THE LINE FROM FILE
while((line = br.readLine()) != null)
{
// PRINT THE LINE
System.out.println(line);
}
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
// RELEASE MEMORY
line = null;
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
How to read bytes from file using Java BufferedReader
/* How to read bytes from file using
java BufferedReader Example
Save with file name BufferedReaderExample6.java */
import java.io.*;
public class BufferedReaderExample6
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// FileInputStream DECLARATION
FileInputStream fis = null;
// int TO READ byte FROM FILE
int ch;
try
{
fis = new FileInputStream("BufferedReaderExample6.java");
ir = new InputStreamReader(fis);
br = new BufferedReader(ir);
int i = 1;
// GET THE bytes FROM FILE
while((ch = br.read()) !=-1)
{
// PRINT THE CHARACTER
System.out.print((char) ch);
if( (i%10) == 0)
br.skip(3);
i++;
}
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
// SHOULD CLOSE STREAMS FINALLY
try
{
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}
How to read bytes from file using java BufferedReader
/* How to read bytes from file using
java BufferedReader Example
Save with file name BufferedReaderExample7.java */
import java.io.*;
public class BufferedReaderExample7
{
public static void main(String args[])
{
// java.io.BufferedReader DECLARATION
java.io.BufferedReader br = null;
// InputStreamReader DECLARATION
InputStreamReader ir = null;
// FileInputStream DECLARATION
FileInputStream fis = null;
// int TO READ byte FROM FILE
int ch;
try
{
fis = new FileInputStream("BufferedReaderExample7.java");
ir = new InputStreamReader(fis);
br = new BufferedReader(ir);
int i = 1;
if(br.ready())
{
// GET THE bytes FROM FILE
while((ch = br.read()) !=-1)
{
// PRINT THE CHARACTER
System.out.print((char) ch);
if(br.markSupported())
{
if(i<30)
{
if((i%10) == 0)
br.mark(i);
if((i%20)==0)
{
br.reset();
}
}
if((i%30)==0)
break;
}
i++;
}
}
}
catch(Exception e)
{
System.out.println("Error Occurred : "+e.getMessage());
}
finally
{
//SHOULD CLOSE STREAMS FINALLY
try
{
if(br!=null)
br.close();
if(ir!=null)
ir.close();
}
catch(Exception ex)
{
System.out.println("Error Occurred : "+ex.getMessage());
}
}
}
}