Pattern p = Pattern.compile("^[0-9]{0,3}$");
Matcher m = p.matcher(in);
if (m.find()) {
JOptionPane.showMessageDialog(null, " 4 integers please");
}
It is a button that adds numbers
Trying to create exception that limits amount of numbers in dialog , it detects if the number is within the limit but does not stop the program.
I do not know the context of this code, but it does not call for a custom exception. Just use a loop to display the dialog if the user enters an invalid input:
Pattern p = Pattern.compile("^[0-9]{0,3}$");
Matcher m = p.matcher(in);
while (!m.find()) {
in = JOptionPane.showInputDialog(null, "Please only enter four integers:");
m = p.matcher(in);
}
// ...
Also, you want to change if(m.find()) to if(!m.find()) otherwise the "Please only enter four integers:" dialog will only show when the user enters the correct number of integers.
If you must use exceptions, just create a class that extends the Exception
class:
public class MyException extends Exception {
public MyException(int amount) {
super("Only " + amount + " integers are allowed");
}
}
And implement it in your if statement:
if (!m.find()) {
throw new MyException(4);
}
You've really provided less than needed code..
But here is a way to fire an event when the characters input in your TextArea exceed 3.
Lets say your TextArea is named txtArea.
txtArea.textProperty().addListener((observable, oldValue, newValue) -> {
if(newValue.length()>3){
JOptionPane.showMessageDialog(null, " 4 integers please");
//Do whatever you need after the Alert is shown
txtArea.setText(oldValue);
}
});
You can simply use in.matches("\\d{4}") as the condition and add to the textarea only if this condition is true.
import javax.swing.JOptionPane;
public class Main {
public static void main(String[] args) {
String in = JOptionPane.showInputDialog("Number: ");
if (in.matches("\\d{4}")) {
// ...Code to add the value to the textarea
} else {
JOptionPane.showMessageDialog(null, "Only 4 digits please.");
}
}
}