Files

[Arsho, Ayan]

<code>
consider the code below:
import java.io.*;
class filo{
static byte h[];
public static void main(String[] args) throws IOException{
byte b[] = {'J','A','V','A','2'};
FileOutputStream fos = new FileOutputStream("java.txt");
fos.write(b);
fos.close();
FileInputStream fis = new FileInputStream("java.txt");
int i = fis.read();
System.out.println(fis.available()+" and "+i);
}
}
Why does fis.available() print 4 shouldn't it be 5? and how does the fis.read() print 74?
Would appreciate a reply?
Thanks
</code>

[Shivaji Marathe]

Are you sure this code compiles and runs? The array b is of type byte and you are assigning char values to it, without uding any explicit cast.
The compiler is not going to like it.
Can you post a version of the code that actually compiles and runs?

[Arsho, Ayan]

Hi Shivaji :
The code complies and runs perfectly.
DID u try it ???
Thanks

[Anonymous]

well I tried it and the code does not compile!!!

[Roy Ben Ami]

ok
let's see.
as for the first question im no expert but in the documentation it says: available: the number of bytes that can be read from this file input stream without blocking.
maybe it prints 4 and not 5 because of that blocking thing (no idea sorry).
as for the second question the char J is converted to a byte (which is 74 when printed out). when you use the read method you get the first byte i.e 74 and it prints it.
you can convert it (cast) it back to char and then print it and it will give u J.

[patrick tang]

interesting question.
i've tried the code and notice
that fis.avaialable() will always return
b.length()-1. so 5-1=4. but i dont know why.
as fis.read() will return an integer, only
8 less significant bits of integer is used.
74 is the integer(ascii?) value of J.

[Deepti Dixit]

Why does this print JAV2 instead of JAVA2 ?

import java.io.*;
class filo{
static byte h[];
public static void main(String[] args) throws IOException{
String s = "JAVA2";
byte b[] = s.getBytes();
FileOutputStream fos = new FileOutputStream("java.txt");
fos.write(b);
fos.close();
FileInputStream fis = new FileInputStream("java.txt");
StringBuffer sb = new StringBuffer();
System.out.println(fis.available());
do {
for (int i = 0; i <= fis.available(); i++)
{
char c = (char)fis.read();
sb.append(new Character(c));
}
} while (fis.read() != -1);
System.out.println(sb.toString());
}
}  

[Shivaji Marathe]

Deepti :
I am not sure why the second A is missing from the output. Try the following code,it prints the text back properly.

 
import java.io.*;
class Filo{
public static void main(String[] args) throws IOException{
String s = "JAVA2";
byte b[] = s.getBytes();
for (int i=0; i<b.length;i++) {
System.out.println("value is b is "+ (char)b[i]+ " i is " + i);
}
FileOutputStream fos = new FileOutputStream("java.txt");
fos.write(b);
fos.close();
FileInputStream fis = new FileInputStream("java.txt");
StringBuffer sb = new StringBuffer();
byte b2[]= new byte [fis.available()];
fis.read(b2);
for (int i=0; i<b2.length;i++) {
System.out.println("value is b2 is "+ (char)b2[i]+ " i is " + i);
}
}
}

Ayan :
Of course I tried to compile the code and it fails at the line that the array of chars is assigned to the array of bytes. I am using JDK 1.3.1

[Roy Ben Ami]

weird!
i think its a bug actually.
under jdk 1.4.0 BETA it compiles succesfully!
you sure under jdk 1.3.1 it doesnt?

[Andrew Cheng]

To Arsho:

int i = fis.read();
System.out.println(fis.available()+" and "+i);

In your code,you read one which is i and the left in the stream is now 4.
If you change the code above to,

int a = fis.availble();
int i = fis.read();

System.out.println(a + " and " + i);
You should get "5 and 74"
To Deepti:

for (int i = 0; i <= fis.available(); i++)
{
  char c = (char)fis.read();
  sb.append(new Character(c));
}

In your code,the value of "fis.available()" will
be decreased by 1 when you read from the stream and the value is not const.You should change the code to the following,and you can get the right result.

int ava = fis.available(); 
for (int i = 0; i < ava; i++)
{
  char c = (char)fis.read();
  sb.append(new Character(c));
}