avoid Number Format Exception while parseing to integer - number-formatting

Question

I'm trying to check if the text area has only numbers or not, but i got this problem Number Format Exception while clicking on the Edit Button, any Ideas how to solve it.
ArrayList<CarRental> List= CarRent.getList();
String text=EditTF.getText().trim();
char [] txt=text.toCharArray();
Character a=null;
boolean isnotDigit=false;
int index;
for(int i=0;i<txt.length;i++)
{
if(!a.isDigit(txt[i]))
{
isnotDigit=true;
break;
}
else
{
isnotDigit=false;
continue;
}
}
if(isnotDigit==false)
{
index=Integer.parseInt(text.trim());
PrintList_Summary.setIndex(index);
EditDetails.nameTF.setText(List.get(index).getName());
EditDetails.sizeCOB.setSelectedItem(List.get(index).getSize());
EditDetails.daysTF.setText(List.get(index).getDays()+"");
if(List.get(index).getCarType().equalsIgnoreCase("Luxury"))
{
EditDetails.LuxRB.setSelected(true);
}
else if(List.get(index).CarType().equalsIgnoreCase("Truck"))
{
EditDetails.truckRB.setSelected(true);
}
if(List.get(index).getDriver())
{
EditDetails.yesRB.setSelected(true);
}
else
{
EditDetails.noRB.setSelected(true);
}
EditDetails.Frame.setVisible(true);
}
else
{
JOptionPane warning=new JOptionPane();
warning.showMessageDialog(null,"Element Index CAN ONLY be an INTEGER.","Invalid Index",WIDTH);
}

Answer 1

Use try catch to handle exceptions.
try{
index = Integer.parseInt(text.trim());
//etc
}catch(NumberFormatException ex){
//whatever happens when the exception is thrown (not an integer)
}
You can use that instead of the if(!a.isDigit(txt[i])) for. If it can't be parsed, then it will go intro the catch.
Also, you can use !isnotDigit instead of isnotDigit == false.

Answer 2

I would use String.matches() for your check instead of doing it yourself. Scrap the for-loop and change your if-condtion from isnotDigit==false to text.matches("[0-9]+"). After this Integer.parseInt(text) should definitly work.
This uses a regular expression to check if your string consists only of digits and at least one digit. For further reference on regular expression see the javadoc for Pattern.