I am currently working on a project which is basically a contact tracing form. The feature I am trying to implement is that when the "print" button is pressed, it enters the data to a notepad text. Although this project is just for fun, I am trying to complete it so that I can learn more about java.
Here is my code:
package com.company;
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.IOException;
public class Main extends JFrame implements ActionListener {
//Initialization of Form
JPanel panel;
JLabel Name_label;
JLabel Address_label;
JLabel Temp_label;
JLabel Age_label;
JLabel Contact_label;
JLabel Date_label;
JLabel msg_label;
JLabel msg2_label;
static JTextField address_text;
static JTextField name_text;
static JTextField age_text;
static JTextField temp_text;
static JTextField cn_text;
static JTextField date_text;
JButton submit, exit, print;
Main() {
//Name Label
Name_label = new JLabel();
Name_label.setText("Name: ");
name_text = new JTextField();
//Date Label
Date_label = new JLabel();
Date_label.setText("Date: ");
date_text = new JTextField();
//Address Label
Address_label = new JLabel();
Address_label.setText("Complete Address: ");
address_text = new JTextField();
//Contact Number
Contact_label = new JLabel();
Contact_label.setText("Contact Number");
cn_text = new JTextField();
//Age Label
Age_label = new JLabel();
Age_label.setText("Age:");
age_text = new JTextField();
//Temperature Label
Temp_label = new JLabel();
Temp_label.setText("Temperature: ");
temp_text = new JTextField();
//Submit
submit = new JButton("SUBMIT");
panel = new JPanel(new GridLayout(9, 3));
exit = new JButton("EXIT");
print = new JButton("Print");
//Message
msg_label = new JLabel();
msg2_label = new JLabel();
//Adding elements
panel.add(Name_label);
panel.add(name_text);
panel.add(Date_label);
panel.add(date_text);
panel.add(Address_label);
panel.add(address_text);
panel.add(Contact_label);
panel.add(cn_text);
panel.add(Age_label);
panel.add(age_text);
panel.add(Temp_label);
panel.add(temp_text);
panel.add(msg_label);
panel.add(msg2_label);
panel.add(submit);
panel.add(exit);
panel.add(print);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
//Listeners
submit.addActionListener(this);
add(panel, BorderLayout.CENTER);
setTitle("Contact Tracing Form");
setSize(1000, 530);
setVisible(true);
exit.addActionListener((event) -> System.exit(0));
print.addActionListener(note());
}
private ActionListener note() {
File file = new File("/users/agcao/contactform.txt");
String name = name_text.getText();
String date = date_text.getText();
String address = address_text.getText();
String age = age_text.getText();
String cn = cn_text.getText();
String temp = temp_text.getText();
FileWriter fw = null;
try {
fw = new FileWriter(file.getAbsoluteFile());
} catch (IOException e) {
e.printStackTrace();
}
assert fw != null;
BufferedWriter bw = new BufferedWriter(fw);
try {
bw.write(name);
bw.write(date);
bw.write(address);
bw.write(age);
bw.write(cn);
bw.write(temp);
} catch (IOException e) {
e.printStackTrace();
}
//step2: write it
try {
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("Done");
return null;
}
public static void main(String[] args) throws IOException {
new Main();
}
@Override
public void actionPerformed(ActionEvent e) {
//Initialization
String name = name_text.getText();
double tempe = Double.parseDouble(temp_text.getText());
int Iage = Integer.parseInt(age_text.getText());
//Process
if (Iage < 15 && tempe >= 37.5)
msg_label.setText("Sorry, " + name + ", You cannot enter this establishment due to your age and temperature!");
else if (tempe >= 37.5)
msg_label.setText("Sorry, " + name + ", You cannot enter this establishment due to your temperature!");
else if (Iage < 15)
msg_label.setText("Sorry," + name + "you cannot enter this establishment due to your age!");
else
msg_label.setText("Hello " + name + ", You may enter this building. Thank you");
}
}
enter code here
sorry if it is too redundant or poorly made. I am still currently trying to become a better developer. Thanks
There's nothing wrong with your file-writing code, the problem is your return value. In the note() method, you specify that it returns an ActionListener, and you add that ActionListener to the print component. But if I look at your code, you don't return any ActionListener at all! You just return null;. The fix is simple: just return the ActionListener, not null. Below is your note() method, modified. For the sake of brevity, I have trimmed it to the first 3 lines.
private ActionListener note() {
return new ActionListener() {
@Override
public void actionPerformed(ActionEvent event) {
File file = new File("contactform.txt");
String name = name_text.getText();
String date = date_text.getText();
...
}
};
}
Now, the code above uses something called an anonymous class. I create a new subclass of ActionListener where I've overridden the actionPerformed() method, and then I return it. Because ActionListener only has one method, though, this code can be shortened even further by using a lambda expression. Here's an example using a lambda:
private ActionListener note() {
return (event) -> {
File file = new File("contactform.txt");
String name = name_text.getText();
String date = date_text.getText();
...
};
}
Another possibility, using a lambda, is to instead of returning an ActionListener, you insert the lambda when you add the ActionListener to the print component. This will work just as well, without modifying the note() method:
print.addActionListener((event) -> note());