Error is my code please help

Question

I have created a try-catch statement, I have also created a home made Invalid value exception class. I have also thrown the InvalidValueException in a calculate method in a seperate class. I am getting the error of unreachable catch block. Here is my code for this process. Please Help
private void runPayroll(List employees)
Collections.sort(employees, new PersonComparator());
// place the following code in a try-catch statement to check for the following errors
//- InvalidValue (the pay units must be a decimal number > 0)
try
double payRate = jtfPayRate.getText();
catch (InvalidValueException ivEx)//THIS IS WHERE I AM GETTING MY ERROR
JOptionPane.showMessageDialog(this, "the pay units must be a decimal number > 0", "Error Message", JOptionPane.ERROR_MESSAGE);
return;
// loop through all of the employees in the collection
Iterator iterator = employees.iterator();
StringBuffer output = new StringBuffer("");
while (iterator.hasNext())
Employee employee = (Employee)iterator.next();
output.append( employee.toString() + "\n" );
//InvalidValueException class
public class InvalidValueException extends Exception
public  InvalidValueException(double payUnit)
//super(payUnit);
public String getLocalizedMessage()
return "Amount must be > 0";
//PayCheck class this is where I throw the exception
public abstract double calculate(double payUnit, double payRate)
throws InvalidValueException;

Answer 1

That catch block is never reached because
double payRate = jtfPayRate.getText();will never throw an InvalidValueException (it doesn't even know about it). I assume jtfPayRate is a textfield? If so, I am suprised the compiler doesn't give you an incompatible types error first, since you are trying to put a string into a double value with the above statement.
I think what you are trying to do is this:
try {
  double payRate = Double.parseDouble(jtfPayRate.getText());
catch(NumberFormatException ex) {
  throw new InvalidValueException(...);
}You may want to pass an error message string to your self made exception, by the way, and call super(message) in the constructor of it.