Java SE (Java Platform, Standard Edition)

When the JOptionPane opens, I cannot close it with the close-button at the top right of the window. The cause is the for loop but I need it to get sure that the user really inputs digits and not letters. When I try to close the JOptionPane, the catch option runs, and I cannot close the JOptionPane untill I type som digits in the age textfield. Can I get through this problem?

for(;;)
			{

				try
				{
						showMessageDialog(this,null,"Input some data", CLOSED_OPTION)

						String str_name = name.getText();
						int int_age= Integer.parseInt(age.getText());		
						break; 
				}catch(NumberFormatException e)
				{
					JOptionPane.showMessageDialog(this, "Numerical value!","Error", JOptionPane.ERROR_MESSAGE);
				}
			}