Hi guys,
The case is: prompts an input for user to enter an integer value that is must be greater than 0 and of course is not an alphabet.
What I have done: I could use Handling Exceptions to control the value of the input not to be an alphabet or be greater than 0 but seperately. But the problem is I do not know how to combine them.
Anyone can tell me?
Thx
Message was edited by:
Emotions
If you have a JTextField you can add an actionListener and then check in actionperformed the value. If not valid throw some Exception.
class MyClass implements ActionListener {
JTextField field;
public MyClass(){
//.... your code
field = new JTextField();
field.addActionListener(this);
//your code
}//end of ctor
public void actionPerformed(ActionEvent event){
if( event.getSource() == field ){
//do some validation
if( notValid ){
throw new Exception("invalid value for field");
}
}//end of class
ps: Make sure to subclass your own exception, catch it an display some validation message
check out the java tutorials on swing
http://java.sun.com/docs/books/tutorial/uiswing/index.html
and events (part of swing tutorials)
http://java.sun.com/docs/books/tutorial/uiswing/events/index.html
Here are my codes, but I dont know where I can put a condition "if" to check whether an integer is greater than 0 or not.
import javax.swing.*;
public class Try
{
public static void main (String[] args)
{
boolean invalidNumber=true;
while(invalidNumber)
{
String input=JOptionPane.showInputDialog("Enter an integer");
try
{
int userInput=Integer.parseInt(input);
invalidNumber=false;
}
catch (NumberFormatException e)
{
JOptionPane.showMessageDialog(null,"Invalid input");
}
}
}
}
I just get rid of the boolean instead of int j=1; while (j>0)
mport javax.swing.*;
public class Try
{
public static void main (String[] args)
{
int j=1;
while (j>0)
{
String input=JOptionPane.showInputDialog("Enter an integer");
try
{
int num=Integer.parseInt(input);
if (num>0)
{
JOptionPane.showMessageDialog(null,num);
break;
}
else
{
JOptionPane.showMessageDialog(null,"Invalid number");
}
}
catch(NumberFormatException e)
{
JOptionPane.showMessageDialog(null,"Invalid number");
}
}
}
}
