Introduction
The Java.io InputStreamReader is the class used to turn the byte (which is in the form of text) into the characters. Here the text will be in UTF - 8 format, so to read the characters in that format use input stream reader which will wraps the file input stream.
Conceptual
figure
Declaration
Java.io InputStreamReader class is declared below:
Public abstract class InputStreamReader extends Reader Fields
Java.io InputStreamReader class fields are:
- Protected Object Lock : For synchronize operations this object is used in InputStreamReader.
Table
| Constructor | Description |
|---|---|
| InputStreamReader(InputStream in) | The function of this constructor is to create the input stream reader instance. |
| InputStreamReader(InputStream in, Charset cs) | The function of this constructor is to create the input stream reader instance with specified charset. |
| InputStreamReader (InputStream in, String CharsetName ) | The function of this constructor is to create the input stream reader instance with specified name of charset. |
Table
| Method | Description |
|---|---|
| void close () | The function of this method is to close the present stream and associated to input stream systems resources are released. |
| Boolean ready () | The function of this method is to check the stream is ready to read or not. |
| int read(Char[] cbuf, int off, int n) | By using this method it reads the data up to ‘n’ bytes from the character stream into an array of characters. |
| String getEncoding() | The function of this method is to get the name of encoded character which was used by this input stream. |
| int read() | The function of this method is to read only one character. |
Description
From the following classes, methods are inherited to the input stream reader class.
- Java.io.Object
- Java.io.Reader
Examples
Usage of void close() method.
[c]import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
public class InputStreamReader
{
public static void main(String[] args) throws IOException
{
FileInputStream fis = null;
InputStreamReader isr =null;
int i;
char c;
try {
// creating a new input stream reader
fis = new FileInputStream("D:/test.txt");
isr = new InputStreamReader(fis);
// To close the input stream reader
isr.close();
System.out.print("close() method accessed");
// To call read() method
i=isr.read();
c=(char)i;
System.out.println(c);
} catch (Exception e) {
// print if any error occurs
//System.out.print("stream closed");
} finally {
// It closes the stream and releases all the resources associated with this stream
if(fis!=null)
fis.close();
if(isr!=null)
isr.close();
}
}
}[/c]
Output
The result will be as follows.
[c]close() method accessed[/c]
Usage of Boolean ready () method.
[c]import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
public class InputStreamReader
{
public static void main(String[] args) throws IOException
{
FileInputStream fis = null;
InputStreamReader isr =null;
boolean bl = false;
int i;
char c;
try {
// Creating a new input stream reader
fis = new FileInputStream("D:/test.txt");
isr = new InputStreamReader(fis);
// To read into the char buffer
while((i=isr.read())!=-1)
{
// To converts integer to character
c=(char)i;
// To print the character
System.out.println("Character read: "+c);
// It returns true if the next read is permitted
bl = isr.ready();
// To print
System.out.println("Ready to read: "+bl);
}
} catch (Exception e) {
// print error
e.printStackTrace();
} finally {
// It closes the stream and releases all the resources associated with this stream
if(fis!=null)
fis.close();
if(isr!=null)
isr.close();
}
}
}[/c]
Output
The result will be as follows.
[c]Character read: S
Ready to read: true
Character read: P
Ready to read: true
Character read:
Ready to read: true
Character read: L
Ready to read: true
Character read: E
Ready to read: true
Character read: S
Ready to read: true
Character read: S
Ready to read: true
Character read: O
Ready to read: true
Character read: N
Ready to read: true
Character read: S
Ready to read: false
[/c]
Key Points
- The Java.io InputStreamReader is the class used to turn the byte (which is in the form of text) into the characters.
- Here the text will be in UTF - 8 format, so to read the characters in that format use input stream reader which will wraps the file input stream.