I want to code for the next and previous buttons. I have made the action listener but do not know how to code for next and previous buttons.
My code is as follows:
public class panel extends OrderSystem {
final JTextField items;
final JTextField number;
final JTextField cost;
final JTextField amount;
public panel() {
JFrame myFrame = new JFrame();
myFrame.setLayout( new FlowLayout() );
myFrame.setTitle("GUI Demo - ISTE-121");
myFrame.pack();
myFrame.setLocation(600,300);
myFrame.setSize(400,200);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setVisible(true);
JPanel order = new JPanel();{
order.setLayout(new GridLayout(5,5,2,2));
myFrame.add(order, BorderLayout.CENTER);
order.add(new JLabel("Item no:", SwingConstants.RIGHT));
order.add(items = new JTextField(3));
order.add(new JLabel("Number of:", SwingConstants.RIGHT));
order.add(number = new JTextField(3));
order.add(new JLabel("Cost", SwingConstants.RIGHT));
order.add(cost = new JTextField(3));
order.add(new JLabel("Amount owed:", SwingConstants.RIGHT));
order.add(amount = new JTextField(10));
amount.setEditable(false);
JPanel buttons = new JPanel();
buttons.setLayout(new GridLayout(1,1,2,2));
myFrame.add(buttons ,BorderLayout.CENTER);
JButton calculate;
buttons.add(calculate=new JButton("Calculate"));
calculate.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
double cost1 = new Double(cost.getText().trim()).doubleValue();
double number1 = new Double(number.getText().trim()).doubleValue();
double result = cost1*number1;
amount.setText(String.valueOf(result));
}
});
JButton save;
buttons.add(save = new JButton("Save"));
save.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e) {
try{
// Assume default encoding.
FileWriter fw = new FileWriter("data.csv",true);
BufferedWriter bufferedWriter = new BufferedWriter(fw);
bufferedWriter.write("\r\n");
bufferedWriter.write("\"ItemCode:\""+"\""+ items.getText() +"\""+",");
bufferedWriter.write("\"ItemNumber:\""+"\""+number.getText()+"\""+",");
bufferedWriter.write("\"ItemCost:\""+"\""+cost.getText()+"\""+",");
bufferedWriter.write("\"AmountOwned:\""+"\""+amount.getText()+"\""+",");
bufferedWriter.close();
}
catch(IOException ex) {
System.out.println(
"Error writing to file '"
+ "'");
// Or we could just do this:
// ex.printStackTrace();
}
}}
);
JButton clear;
buttons.add(clear=new JButton("Clear"));
clear.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
items.setText(null);
number.setText(null);
cost.setText(null);
amount.setText(null);
}});
JButton exit;
buttons.add(exit= new JButton("Exit"));
exit.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
System.exit(0);
}
});
}
JPanel button = new JPanel();
{
button.setLayout(new GridLayout(5,5,2,2));
myFrame.add(button ,BorderLayout.SOUTH);
JButton load;
button.add(load=new JButton("Load"));
load.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
try {
String csvFile = "Documents/workspace/samp/data.csv";
//create BufferedReader to read csv file
BufferedReader br = new BufferedReader(new FileReader("data.csv"));
String line = "";
StringTokenizer st = null;
int lineNumber = 0;
int tokenNumber = 0;
//read comma separated file line by line
while ((line = br.readLine()) != null) {
lineNumber++;
//use comma as token separator
st = new StringTokenizer(line, ",");
while (st.hasMoreTokens()) {
tokenNumber++;
//display csv values
System.out.print(st.nextToken() + " ");
}
System.out.println();
//reset token number
tokenNumber = 0;
}
} catch (Exception e1) {
System.err.println("CSV file cannot be read : " + e1);
}
}
}
);
JButton next;
button.add(next=new JButton("Next>"));
next.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
}
});
JButton prev;
button.add(prev=new JButton("<Prev"));
prev.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
}
});
}
}
}
Use List to store the data, so when your data look like say:
a.csv - b.csv - c.csv
So when you are reading b.csv, sp using listIterator, iterating to previous could be done using iterator.previous() i.e. reading a.csv while iterator.next() will lead you reading next file (forward) i.e. c.csv.
Which means you could make use of dequeue which maintains previous and next entry in the list.