using .length()

[jake mullet]

Hello JavaGurus, I need to know if everyfile I read in has a 'Z' contained within the last line of the file. in particular it is the 10th byte from the EOF, but each file is different in length, so I'm using the .length() to get the total size but how would I say sBuffer.length() - 10 , then get the charAt() to check if it is a 'Z' thanks for anyone's help
import java.io.*;
import java.util.*;

public class injRecFix{
static PrintWriter prntWrter;

public static void main(String[] args){
char[] chBuffer =null;
boolean bReadFile = false;
String sINFileName = null;
String sOUTFileName = null;
int i;

InputStream fin;
File outputFile = new File("newPunchFile.txt");

if(sINFileName == null)
sINFileName = "Punch.001";

try {
fin = new FileInputStream(sINFileName);
prntWrter = new PrintWriter(new FileWriter(outputFile));
} catch (IOException except) {
sINFileName = "Punch.001";
try {
fin = new FileInputStream(sINFileName);
} catch (IOException eIO) {
fin = null;
}
}
if(fin != null) { // dumping PunchFile into chBuffer
try {
chBuffer = new char[fin.available()];
int iC = 0;
while(iC < chBuffer.length) {
i = fin.read();
chBuffer[iC] = (char)i;
iC++;
}
fin.close();
bReadFile = true;
} catch (IOException except) {
bReadFile = false;
}
}
if (bReadFile) {
// Convert buffer into a string.
String sBuffer = new String(chBuffer, 0, chBuffer.length);
sBuffer.charAt(??)
//System.out.println(sBuffer.length());
}
}//end main()
}//end class injRecFix

[Richard Boren]

I'm not a guru, but String has a method indexOf() that will return the location of the string or character passed to it. If non is found it returns a -1.

    int index = sBuffer.indexOf( "z" ) ; 
    if ( index != -1 ) // then z is in the string at index
    {...}

[Art Metzer]

Hi, Jake. Let me preface all this by saying, I'm not a Java guru, either.

import java.io.*;
 
public class TenthFromLast {
 
    // The byte the tenth byte from the last
    // must be equal to.  Limited to ASCII
    // character set.
    public static final byte CHECK = (byte) 'Z';
 
    public static void main( String[] args ) {
 
        TenthFromLast tfl = new TenthFromLast();
        System.out.println( tfl.match() );
    }
 
    public boolean match() {
 
        RandomAccessFile raf = null;
        byte linchpin = 0;
        boolean temp = false;
 
        try {
            raf = new RandomAccessFile( "C:\\zonk.txt", "r" );
 
            // Go to the tenth byte from the end of the file.
            raf.seek( raf.length() - 10 );
 
            // Store this tenth byte from the end
            // in this byte.
            linchpin = raf.readByte();
        }
        catch ( FileNotFoundException fnfe ) {
 
            fnfe.printStackTrace();
        }
 
        catch ( IOException ioe ) {
 
            ioe.printStackTrace();
        }
 
        // If the byte found isn't the one you're
        // looking for, display to the user what
        // was found at length() - 10.
        if (!( temp = ( linchpin == CHECK ) ) ) {
 
            System.out.println( "Tenth byte from last = " + (char) linchpin );
        }
 
        try {
            raf.close();
        }
        catch ( IOException ioe ) {
 
            ioe.printStackTrace();
        }
 
        // TRUE means Z was tenth from the end,
        // FALSE means it wasn't.
        return temp;
    }
}

I should note that the contents of C:\zonk.txt are

<font size="2.0">
ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789

The method match() goes to the tenth byte from the end of the file and compares that byte to the byte representation of Z, and returns true if they match, false if they don't.
It's not the soundest solution, but I think it'll work. Hope it helps.
Art
[This message has been edited by Art Metzer (edited May 09, 2001).]

[Susan Delph]

I'm definitely NOT a Java Guru, but....
lastIndexOf('z') will find the last occurrence of 'z' in the String.
int index = sBuffer.lastIndexOf('z');
This will search the String backwards, and index will be set to whatever position the final 'z' of the String is found in.
(If no 'z' is found, index is set to -1, as Richard explained above.)
Susan

[This message has been edited by Susan Delph (edited May 09, 2001).]

[Susan Delph]

Actually, dump my above suggestion. This is better -- in my opinion:

public class FindZ
{
  public static void main(String[] args)
  {
    String str = "z123z567z123456789"; //last z is position 8.
    int minus10 = str.length() - 10;
    if (str.charAt(minus10) == 'z')
       System.out.println("true");
  }
}

It printed out 'true' when I ran this.
Susan

[This message has been edited by Susan Delph (edited May 09, 2001).]