Read and Write depending on file contents

[paulhenderson]

Hi All,

I am fairly new to java, i am trying to write a simple file that reads the contents of a file and then dependent on the contents it writes a new value to a file.
It is a basic file that says either Logged In or Logged Out

I can get a application to read from a file and write to a file seperatley but when i try to combine them with a if then else statement i get a few error messages such as "try without catch" and illegal start of type catch (IOException e)...

Here is the code I am using, can anyone give me any pointers:

import java.io.*;

public class Write
{
// Main method
public static void main (String args[])




{
// Stream to write file
FileOutputStream fout;

// Stream to read file
FileInputStream fin;



try

{

fin = new FileInputStream ("test.txt");
fout = new FileOutputStream ("test.txt");

if (fin = "Logged In");
{

// Open an input stream
fout = new FileOutputStream ("test.txt");

// Print a line of text
new PrintStream(fout).println ("Logged Out");

// Close our output stream
fout.close();

}

else if

{
// Open an output stream
fout = new FileOutputStream ("test.txt");

// Print a line of text
new PrintStream(fout).println ("Logged In");

// Close our output stream
fout.close();

}

// Display the status to the user
System.out.println ("You have been " + fin);


}

// Catches any error conditions
catch (IOException e)
{
System.err.println ("Login/Logout Failed.");
System.exit(-1);
}
}
}

[r035198x]

You should use Readers and Writers for character data not streams.

This line is definitely wrong

if (fin = "Logged In");

for several reasons.
Chief among them being
1.) trying to assign a string to a FileInputStream object.
2.) attempting to do an equals check on strings using = instead of using the equals method.
3.) the evil semicolon that is at the end of the if implying that the if is useless.

[paulhenderson]

Thanks r035198x

I noticed the ";" just before I recieved your post.

What should I assign to the FileInputStream object if not a string?
I have tested the equals check using "==" instead of the "=" and i get an error:

"Wite.java:21: incomparable types: java.io.FileInputStream and java.lang.String if (fin == "Logged In"){

What should I be using for the equals if not == or !=, Thanks.

[r035198x]

1.) You are still usings streams. Use FileReader and FileWriter instead.
2.) You are still comparing a FileInputstream with a String.