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Message:

Update Record method not working :(

Posted by Paul Michael on December 19, 2001 at 12:06 PM

Hello All:

Having problems with my "UpdateRec" method maybe you can help. Please create two text files (i.e. Notepad), HardwareStore.java and Record.java and save them as (all files) ".java" files; launched JBuilder or Forte or whatevet Java editor you use and run it. Create a "New record" then 'Save Changes' and then click on the "Update Record" command button, edit the name, quqnity or price and you will see what I mean.

Thank you and have a Happy Holiday!
PM

//HardwareStore.java
// This program reads a random access file sequentially,
// updates data already written to the file, creates new
// data to be placed in the file, and deletes data
// already in the file.
import java.awt.*;
import java.io.*;
import java.awt.event.*;
import Record;

public class HardwareStore extends Frame
implements ActionListener {
private Button updateButton, // update record
newButton, // add new record
deleteButton, // delete record
done; // quit program

private UpdateRec update; // dialog box for record update
private NewRec newRec; // dialog box for new record
private DeleteRec deleteRec; // dialog box for delete record
private RandomAccessFile file; // file from which data is read
private Record data;

public HardwareStore()
{
super( "Fred's Hardware Store Inventory" );

// Open the file for existing and\or create new + open
try {
file = new RandomAccessFile("hardware.dat", "rw" );
}
catch ( IOException e ) {
System.err.println( e.toString() );
System.exit( 1 );
}

data = new Record();
setup();
addWindowListener( new WindowHandler( this ) );
}

public void setup()
{
setSize( 300, 80 );
setLayout( new GridLayout( 2, 2 ) );

updateButton = new Button( "Update Record" );
newButton = new Button( "New Record" );
deleteButton = new Button( "Delete Record" );
done = new Button( "Done" );

updateButton.addActionListener( this );
newButton.addActionListener( this );
deleteButton.addActionListener( this );
done.addActionListener( this );

add( updateButton );
add( newButton );
add( deleteButton );
add( done );

setVisible( true ); // show the Frame

// Create dialog boxes
update = new UpdateRec( file );
newRec = new NewRec( file );
deleteRec = new DeleteRec( file );
}

public void actionPerformed( ActionEvent e )
{
String current = ( String ) e.getActionCommand();

if ( current.equals( "Update Record" ) )
update.setVisible( true );
else if ( current.equals( "New Record" ) )
newRec.setVisible( true );
else if ( current.equals( "Delete Record" ) )
deleteRec.setVisible( true );
else if ( current.equals( "Done" ) )
cleanup();
}

public void cleanup()
{
try {
file.close();
}
catch ( IOException e ) {
System.exit( 1 );
}

setVisible( false );
System.exit( 0 );
}

public static void main( String args[] )
{
HardwareStore inventory = new HardwareStore();
}
}

class WindowHandler extends WindowAdapter {
HardwareStore h;

public WindowHandler( HardwareStore s ) { h = s; }

public void windowClosing( WindowEvent e ) { h.cleanup(); }
}

class UpdateRec extends Dialog
implements ActionListener {
private RandomAccessFile file;
private TextField part, tName, quantity, price;
private Label partLabel, tNameLabel, quantityLabel, priceLabel;
private Button cancel, save;
private Record data;
private int thePartNumber;

public UpdateRec( RandomAccessFile f )
{
super( new Frame(), "Update Record", true );
setSize( 300, 180 );
setLayout( new GridLayout( 6, 2 ) );
file = f;

part = new TextField( 10 );
tName = new TextField( 10 );
quantity = new TextField( 10 );
price = new TextField( 10 );
partLabel = new Label( "Part" );
tNameLabel = new Label( "Tool name" );
quantityLabel = new Label( "Quantity" );
priceLabel = new Label( "Price" );
save = new Button( "Save Changes" );
cancel = new Button( "Cancel" );

part.addActionListener( this );
save.addActionListener( this );
cancel.addActionListener( this );

add( partLabel);
add( part );
add( tNameLabel );
add( tName );
add( quantityLabel );
add( quantity );
add( priceLabel );
add( price );
add( save );
add( cancel );

data = new Record();
}

public void actionPerformed( ActionEvent e )
{
if ( e.getSource() == part ) {
thePartNumber = Integer.parseInt( part.getText() );

if ( thePartNumber < 1 || thePartNumber > 100 ) {
part.setText( "Invalid part number" );
return;
}

try {
file.seek( ( thePartNumber - 1 ) * data.getSize() );
data.read( file );
}
catch ( IOException ex ) {
part.setText( "Error reading file" );
}

if ( data.getPartNumber() != 0 ) {
part.setText( String.valueOf( data.getPartNumber() ) );
tName.setText( data.getPartName() );
quantity.setText( Integer.toString( data.getQuantity() ) );
price.setText( String.valueOf( data.getCost() ) );
}
else
part.setText( thePartNumber + " does not exist" );
}
else if ( e.getSource() == save ) {
try {
file.seek( ( thePartNumber - 1 ) * data.getSize() );
data.setPartNumber( thePartNumber );
data.setPartName( tName.getText() );
data.setQuantity( Integer.parseInt( quantity.getText() ) );
data.setCost( ( Double.valueOf(
price.getText() ) ).doubleValue() );
data.write( file );
}
catch ( IOException ex ) {
part.setText( "Error writing file" );
return;
}

setVisible( false );
clear();
}
else if ( e.getSource() == cancel ) {
setVisible( false );
clear();
}
}

private void clear()
{
part.setText( "" );
tName.setText( "" );
quantity.setText( "" );
price.setText( "" );
}
}

class NewRec extends Dialog
implements ActionListener {
private RandomAccessFile file;
private TextField part, tName, quantity, price;
private Label partLabel, tNameLabel, qLabel, priceLabel;
private Button cancel, save;
private Record data;
private int partNum;

public NewRec( RandomAccessFile f )
{
super( new Frame(), "New Record", true );
setSize( 300, 150 );
setLayout( new GridLayout( 5, 2 ) );
file = f;

partLabel = new Label( "Part Number" );
part = new TextField( 10 );
tName = new TextField( 10 );
quantity = new TextField( 10 );
price = new TextField( 10 );
tNameLabel = new Label( "Tool Name" );
qLabel = new Label( "Quantity" );
priceLabel = new Label( "Price" );
save = new Button( "Save Changes" );
cancel = new Button( "Cancel" );

save.addActionListener( this );
cancel.addActionListener( this );

add( partLabel);
add( part );
add( tNameLabel );
add( tName );
add( qLabel );
add( quantity );
add( priceLabel );
add( price );
add( save );
add( cancel );

data = new Record();
}

public void actionPerformed( ActionEvent e )
{
if ( e.getSource() == save ) {
partNum = Integer.parseInt( part.getText() );

data.setPartName( tName.getText() );
data.setQuantity( Integer.parseInt( quantity.getText() ) );
data.setCost( ( new Double( price.getText() ) ).doubleValue() );
data.setPartNumber( partNum );

if ( partNum < 1 || partNum > 100 ) {
part.setText( "Invalid account" );
return;
}

try {
file.seek( ( partNum - 1 ) * data.getSize() );
data.write( file );
}
catch ( IOException ex ) {
part.setText( "Error writing file" );
System.err.println(ex.toString());
return;
}

setVisible( false );
clear();
}
else if ( e.getSource() == cancel ) {
setVisible( false );
clear();
}
}

private void clear()
{
part.setText( "" );
tName.setText( "" );
quantity.setText( "" );
price.setText( "" );
}
}

class DeleteRec extends Dialog
implements ActionListener {
private RandomAccessFile file;
private TextField part;
private Label partLabel;
private Button cancel, delete;
private Record data;
private int partNum;

public DeleteRec( RandomAccessFile f )
{
super( new Frame(), "Delete Record", true );
setSize( 300, 80 );
setLayout( new GridLayout( 2, 2 ) );
file = f;

partLabel = new Label( "Part Number" );
part = new TextField( 10 );
delete = new Button( "Delete Record" );
cancel = new Button( "Cancel" );

cancel.addActionListener( this );
delete.addActionListener( this );
part.addActionListener( this );

add( partLabel);
add( part );
add( delete );
add( cancel );

data = new Record();
}

public void actionPerformed( ActionEvent e )
{
if ( e.getSource() == part ) {
partNum = Integer.parseInt( part.getText() );

if ( partNum < 1 || partNum > 100 ) {
part.setText( "Invalid part number" );
return;
}

try {
file.seek( ( partNum - 1 ) * data.getSize() );
data.read( file );
}
catch ( IOException ex ) {
part.setText( "Error reading file" );
}

if ( data.getPartNumber() == 0 )
part.setText( partNum + " does not exist" );
}
else if ( e.getSource() == delete ) {
try {
file.seek( ( partNum - 1 ) * data.getSize() );
data.setPartNumber( 0 );
data.setPartName( "" );
data.setQuantity( 0 );
data.setCost( 0.0 );
data.write( file );
}
catch ( IOException ex ) {
part.setText( "Error writing file" );
return;
}

setVisible( false );
part.setText( "" );
}
else if ( e.getSource() == cancel ) {
setVisible( false );
part.setText( "" );
}
}
}
*************************************
//Record.java
//A smal sub-routine
import java.io.*;

public class Record {
private int partNumber;
private String partName;
private int quantity;
private double cost;

// Read a record from the specified RandomAccessFile
public void read( RandomAccessFile file ) throws IOException
{
partNumber = file.readInt();
char f[] = new char[ 15 ];

for ( int i = 0; i < f.length; i++ )
f[ i ] = file.readChar();

partName = new String( f );
quantity = file.readInt();
cost = file.readDouble();
}

// Write a record to the specified RandomAccessFile
public void write( RandomAccessFile file ) throws IOException
{
StringBuffer buf;

file.writeInt( partNumber );

if ( partName != null )
buf = new StringBuffer( partName );
else
buf = new StringBuffer( 15 );

buf.setLength( 15 );

file.writeChars( buf.toString() );
file.writeInt( quantity );
file.writeDouble( cost );
}

public void setPartNumber( int p ) { partNumber = p; }

public int getPartNumber() { return partNumber; }

public void setPartName( String f ) { partName = f; }

public String getPartName() { return partName; }

public void setQuantity( int q ) { quantity = q; }

public int getQuantity() { return quantity; }

public void setCost( double c ) { cost = c; }

public double getCost() { return cost; }

// NOTE: This method contains a hard coded value for the
// size of a record of information.
public static int getSize() { return 31; }
}

• getSize() is wrong ping203 December 20, 2001 at 3:34 PM (0)