Java Buffer Reader
When a variable cannot change its value during run time is called a Static way of programming. In this programming, a variable is directly assigned to a value.
Program:
Import java.io.*;
class A
{
public static void main(String s[])
{
int var1=1;
// Here “var1” assigned to 1.
System. out. print ln (“var1 = “+var1);
}
}
Input:
1
Output:
var1=1
Note: The above program is about considering static values of variables in programming.
To access input from the user or to access dynamic values of variables from the keyboard, we use the Scanner class or BufferReader class.
BufferedReader:
- It is a class that reads data from the input stream.
- This class inherits the properties of the Reader class.
- It takes as a string while reading the inputs.
Input Stream:- Java.io package contains Input Stream class.
- This stream represents the set of bytes.
- It is an abstract class.
Abstract Class: Abstract methods are present in this class.An abstract method has an abstract keyword, and these methods don’t have anybody.
The syntax for object creation In Input Stream:
InputStream object1 = new FileInputStream();
Note: To create an object, we use FileInputStream because InputStream is an abstract class.
BufferedReader class Syntax:
public class BufferedReader extends Reader;
Constructors in BufferedReader:
- BufferedReader(Reader r)
- BufferedReader(Reader r, int size)
BufferedReader(Reader r): It is used to generate an Input stream without mentioning or considering the size.
BufferedReader(Reader r, int size): It is used to generate an Input stream with mentioned size.
Methods in BufferedReader class:
- read ()
- close ()
- read (char[] c, int start, int length)
- skip (long s)
- ready ()
- mark ()
- reset ()
- mark supported ()
read():
- It is used to read single characters from the stream.
- It returns -1 if it reaches the end of the input.
- It represents whether the next character is present or not.
- The return type of the read() method is int(Integer).
Syntax:
public int read()
Program:
import java.io.*;
class Example1
{
public static void main(String[] s) throws IOException
{
BufferedReader object2 = new BufferedReader(new InputStreamReader(System.in));
char s1 = (char)object2.read();
System.out.println(s1);
}
}
Input:
A
Output:
A
readLine ():
- It is used to read the entire line of the input.
- It takes input in the form of strings.
Program:
import java.io.*;
class Example19
{
public static void main(String[] s) throws IOException
{
BufferedReader object2 = new BufferedReader(new InputStreamReader(System.in));
String string1 = object2.readLine();
System.out.println(string1);
}
}
Input:
Java
Output:
Java
close ():
- It is used to close the character stream.
- Return type of the close() method is void.
- If the stream has been closed, performing methods like read() and other methods throw an IOException.
read(char[] c, int start, int length):
- It stores the reading characters in the array form.
- It returns the count of characters.
- Integer is the return type.
Syntax:
public int read(char[] c, int start, int length)
- c -It is the Destination buffer
- start – at which index it starts writing characters.
- length -.Several characters.
Program:
import java.io.*;
class Example3{
public static void main(String[] s) throws IOException {
ob1 = new FileInputStream("cse.txt");
BufferedReader object2 = new BufferedReader(new InputStreamReader(ob1));
char c[]=new char[10];
try{
object2.read(c,0,4);
System . out . println(c);
object2.close()
}
catch (IOException E){
System. out. println(E);
}
}
Output:
ABCD
Note: Here In file cse.txt contains input as ABCDEFGHIJKLMNOPQRSTUVWXYZ.
skip(long s):
- It returns the number of skipped characters from the stream.
- Long is the return type.
Syntax:
public long skip(long s)
Program:
import java.io.*;
class Example14
{
public static void main(String s[]) throws IOException
{
Object1 = new FileInputStream(“cse-c.txt”);
BufferedReader b = new BufferedReader(new InputStreamReader(object1));
System . out . print((char)b.read());
b.skip(3);
System . out . print((char)b.read());
}
}Output:
H
oNote: In the cse file we have Hello text we take this as input.
ready():
- It checks whether the input stream is ready to be read or not.
- Return type of ready() method is boolean.
Syntax:
public boolean ready();
Program:
import java.io.*;
class Example18
{
public static void main ( String s[]) throws IOException
{
object1 = new FileInputStream(“cse-c.txt”);
BufferedReader b = new BufferedReader(new InputStreamReader(object1)); System . out . println(“Print true if it is ready otherwise false:”+string2.ready()); b.close();}
}Output:
Print true if it is ready otherwise false: true
mark(int Limit):
- This method is used to represent the present position in the stream.
- Void is the return type.
Syntax:
public void mark(int Limit)
Program:
import java.io.*;
class Example17{
public static void main(String[] s) throws IOException{
object1 = new FileInputStream(“Fruit.txt”);
BufferedReader b = new BufferedReader(new InputStreamReader(object1));
b . mark(1); System . out . println(b.read());
b . close();
}
}
Output:
65
Note: In the fruits file we have content as Apple.
reset ():
- It is used to reset the stream.
- Void is the return type.
Program:
import java.io.*;
class Example10
{
public static void main(String[] s) throws IOException
{
object1 = new FileInputStream(“computerscience.txt”);
BufferedReader b = new BufferedReader(new InputStreamReader(object1));
b.mark(1);
System . out . println(b . read());
b . reset();
b . close();
}
}Output:
67
Note: In the computerscience file we have content like Coding.
mark supported ():
- It is used to check whether it supports the mark() method or not.
- void is the return type.
Syntax:
public void markSupported()
Program:
import java.io.*;
class Example7
{
public static void main(String[] s) throws IOException
{
try {
object1 = new FileInputStream(“computerscience.txt”);
BufferedReader b = new BufferedReader(new InputStreamReader(object1));
System . out . println(“Print True if it supports otherwise False:"+ b.markSupported());
b.close();
}
}
}Output :
Print True if it supports otherwise False: true