Java.io.FilterReader class in Java

Last Updated : 12 Sep, 2023

Abstract class for reading filtered character streams. The abstract class FilterReader itself provides default methods that pass all requests to the contained stream. Subclasses of FilterReader should override some of these methods and may also provide additional methods and fields.
Constructor :

protected FilterReader(Reader in) : Creates a new filtered reader.

Methods:

void close() : Closes the stream and releases any system resources associated with it.Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.
```
Syntax :public void close()             throws IOException  Throws:  IOException
```

void mark(int readAheadLimit) : Marks the present position in the stream.

Syntax :public void mark(int readAheadLimit)            throws IOException  Parameters:  readAheadLimit - Limit on the number of characters that may be read   while still preserving the mark. After reading this many characters,   attempting to reset the stream may fail.  Throws:  IOException

boolean markSupported() : Tells whether this stream supports the mark() operation.

Syntax :public boolean markSupported()  Returns:  true if and only if this stream supports the mark operation.

int read() : Reads a single character.

Syntax :public int read()           throws IOException  Returns:  The character read, as an integer in the range 0 to 65535 (0x00-0xffff),   or -1 if the end of the stream has been reached  Throws:  IOException

int read(char[] cbuf, int off, int len) : Reads characters into a portion of an array.

Syntax :public int read(char[] cbuf,         int off,         int len)           throws IOException  Parameters:  cbuf - Destination buffer  off - Offset at which to start storing characters  len - Maximum number of characters to read  Returns:  The number of characters read, or -1 if the end of the stream has been reached  Throws:  IOException

boolean ready() : Tells whether this stream is ready to be read.

Syntax :public boolean ready()                throws IOException  Returns:  True if the next read() is guaranteed not to block for input,   false otherwise. Note that returning false does not guarantee  that the next read will block.  Throws:  IOException

void reset() : Resets the stream.

Syntax :public void reset()             throws IOException  Throws:  IOException

long skip(long n) : Skips characters.

Syntax :public long skip(long n)            throws IOException  Parameters:  n - The number of characters to skip  Returns:  The number of characters actually skipped  Throws:  IOException

Program :

   //Java program illustrating FilterReader class methods 
  
import java.io.*; 
class FilterReaderdemo 
{ 
    public static void main(String[] args) throws IOException 
    { 
        Reader r = new StringReader("GeeksforGeeks"); 
        FilterReader fr = new FilterReader(r)  
        { 
        }; 
        char ch[] = new char[8]; 
          
        //illustrating markSupported() 
        if(fr.markSupported()) 
        { 
            //illustrating mark() method 
            System.out.println("mark method is supported"); 
            fr.mark(100); 
        } 
          
        //illustrating skip() method 
        fr.skip(5); 
          
        //illustrating ready() 
        if(fr.ready()) 
        { 
            //illustrating read(char[] cbuff,int off,int len) 
            fr.read(ch); 
            for (int i = 0; i < 8; i++)  
            { 
                System.out.print(ch[i]); 
            } 
              
            //illustrating reset() 
            fr.reset(); 
            for (int i = 0; i <5 ; i++) 
            { 
                //illustrating read() 
                System.out.print((char)fr.read()); 
            } 
        } 
          
        //closing the stream 
        fr.close(); 
    } 
} 
 
  

Output :

mark method is supported  forGeeksGeeks

Java.io.FilterInputStream Class in Java

Nishant Sharma

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Java.io.FilterReader class in Java

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