BufferedReader

[wong sheena]

   import java.io.*;
 
public class TestIO{
 

public static void main(String args[]){

 try{
Reader r = new BufferedReader(new FileReader("in"));//line1
 
  }catch(IOException e){}
}
 
} 

Hi all,
I have a problem with line 1.
Not sure what is problem..
I thought since BufferedReader is subclass of Reader , the assignment would be ok.
Can anyone explain? Thanks!

[Barry Gaunt]

No compilation errors for me. What's your problem?
Maybe you are getting an IOException?

[Vivian Josh]

Hi,

This code compiles fine. You should elaborate more on your type of error. May be you have not imported all the needed API classes.

HTH,

Vivian

[Priyam Srivastava]

There aren't any compilation error noe any IOException while running the code!! What exactly the complilation error/excepion you are getting??

[dolly shah]

  import java.io.*;
 
public class TestIo{
 

public static void main(String args[]){
 
 try{
BufferedReader r = new BufferedReader(new FileReader("in"));//line1
 
  }catch(IOException e){}
}
 
}

If you change your code as above you wont find any problem. Because Reader class is abstract, you cannot instantiate it.

[wong sheena]

Hmm..
I'm having a compilation error as follow.Thanks for the quick reply.

   
 
TestIO.java:9: incompatible types
found   : java.io.BufferedReader
required: Reader
                        Reader r = new BufferedReader(new FileReader("in"));
                                   ^
1 error

[Priyam Srivastava]

Well Dolly we aren't instantiating Reader Interface here..we are just assiging the reference of the BufferedReader object to Reader refernce varialble and since BufferedReader implements Reader hence BufferedReader "IS A" Reader..

the code is absolutely fine..sheena I hope you are using javac 1.5 compiler..because that is the only reason I can think of for not compliling the code !!!

[Jesper de Jong]

Do you have a class named 'Reader' (that you wrote yourself) in the same directory as the TestIO class?

[wong sheena]

Do you have a class named 'Reader' (that you wrote yourself) in the same directory as the TestIO class?

There is a class named Reader i wrote myself..After I deleted it, the same error still occur.

[Sergio Tridente]

Make sure you deleted .class file too.

[wong sheena]

Hi all.. The problem it is due to a public class named Reader I wrote myself inside..So i renamed the file from Reader.java to Reader(renamed).java and deleted the Reader.class file..

The compilation succeeded.Thanks all!

[dolly shah]

Bye the way Priyam Reader is not an Interface. It is a class.

Wong, Though the code raise error(Incompatible types) But it compiles & runs fine.

[Priyam Srivastava]

ok mistake accepted it's a class..but still superclass refrence variable can refer to a sub-class object..Polymorphism !!!

[dolly shah]

yeah, you are right