do while error checking help

[powerej]

program is suppose to ask for an input from 1-8, if the user enters a number outside of this range than it will continue to ask until it does, something is wrong and i cant seem to figure it out, i am stuck. Also my if else to see if the user catches the wave seems right to me but only works like half the time. I just really want to know what i am doing wrong here.

   import javax.swing.*; // gets option pane
   import java.text.DecimalFormat; //formats decimals
	
    public class Lab8  {
      
      public static  final int G = 32; //a constant
      public static double waveSpeed;  //a class double variable
      public static String userInput;
   	// method that generates a random wave
       public static double randomWaveSpeed () {
         int depth =	randomNumber(1, 20);
         int length = randomNumber(1, 15);
         waveSpeed = depth / length;
      			
        // determining which wave is selected
         if (depth >= .5){
           
            return deepWaveSpeed(length);
         }
         else 
         
            return shallowWaveSpeed(depth);
      }
      // method that generates a random number
       public static int randomNumber(int low , int hi ){
      
         return (low + (int)(Math.random() * hi));
      }
   		
   	// method that determines the speed of a wave in shallow water	   
       public static double shallowWaveSpeed(int depth ){
        
		   return Math.sqrt((G*depth));
      }
      // method that determines the speed of a wave in deep water
       public static double deepWaveSpeed(int length ){
        
		   return  Math.sqrt((G*length)/(2*Math.PI));
      }
    
      // method that displays whether or not the user caught the wave from 
      // the paddle speed entered
       public static void displayRideOutcome(double paddleSpeed ){
         String output;   
      	        
         if(paddleSpeed > waveSpeed){
           
            DecimalFormat twoDigits = new DecimalFormat("0.00");
         
         // generating output
            output = "Wave speed = " + twoDigits.format(randomWaveSpeed()) + "(ft/sec)" + "\n";
            output += "Paddle speed = " + twoDigits.format(paddleSpeed) + "(ft/sec)" + "\n";      	
            output +=  "You were able to catch the wave.";
         }
         
         else{   
           
            DecimalFormat twoDigits = new DecimalFormat("0.00");
         
         // generating output
            output = "Wave speed = " + twoDigits.format(randomWaveSpeed()) + "(ft/sec)" + "\n";
            output += "Paddle speed = " + twoDigits.format(paddleSpeed) + "(ft/sec)" + "\n"; 
            output += "You were not able to catch the wave.";
         }
      
         //outputing with JOptionPane                
         JOptionPane.showMessageDialog(null, output, "Lab8 (Edward Powers)", JOptionPane.PLAIN_MESSAGE);
      }
      
        // main method			
       public static void main (String[] args)  {
         String userInput;
         double paddleSpeed; 
         int option;     
      
      // a do while loop til the user clicks no
         do {
            do{
               userInput = JOptionPane.showInputDialog("What is your paddle speed (ft/sec)?" + "\n" +
                  											"Valid Range is (1.0 to 8.0)");
            
            // if statement to cancel prog with error message if the user click cancel
               if (userInput == null)
               {
                  JOptionPane.showMessageDialog(null, "User clicked cancel.  The program will exit.",
                     "Lab8 (Edward Powers)", JOptionPane.ERROR_MESSAGE );
                  System.exit(0);
               }	          
              
               paddleSpeed = Double.parseDouble(userInput);
               if (paddleSpeed < 1 | paddleSpeed > 8){
                  userInput = JOptionPane.showInputDialog("What is your paddle speed (ft/sec)?" + "\n" +
                     										"Valid Range is (1.0 to 8.0)");}
               else{          
                  displayRideOutcome ( paddleSpeed);
               }		
               option = JOptionPane.showConfirmDialog(null, "Would you like to continue?", "Lab7 (Edward Powers)", JOptionPane.YES_NO_OPTION );
            
            }
            while (option == JOptionPane.YES_OPTION);
         
         }
            while ( paddleSpeed >= 1 | paddleSpeed <=8);
      }
   }

[Koolioman]

I'm no expert, but I have a working way to use if/else logic and have it reject numbers that are out of the range.

String^ aString = System::Convert::ToString(textBox1->Text);
float a = System::Convert::ToSingle(textBox1->Text);

if (aString->Length == 0)
{
MessageBox::Show(" Unable to calculate");
}

else if (a > 8)
{
MessageBox::Show("Unable to calculate");
}
else
{
MessageBox::Show("Good answer!");
}

Make sure that you use the brackets exactly the way i did, or it won't work right.
If there is only one line of code after the if/else, then you don't need brackets.