Argthtjtr

I have a script that tests the validity of characters entered in order to learn Try/Catch. The numbers must be entered in a strict "$123.45" format or else the Try/Catch prints an error. It needs to be able to catch all integer errors and print them. Currently, if a dollar AND a cent are entered incorrectly the script works fine and prints both errors. However, if ONLY an error is found when entering cents, the print line says begins with "null".

Example (working):
Input:
Please enter amount of sale in form $#.## ("q" to quit): $12d.de

Print:
Invalid dollar format - For input string: "12d"

Invalid cents format - For input string: "de"

Example (NOT working):
Input:
Please enter amount of sale in form $#.## ("q" to quit): $123.de

Print:
nullInvalid cents format - For input string: "de"

The error is in the "+=" in the Catch for myCent:

"myBad += "Invalid cents format - For input string: "" + mySale.substring(mySale.indexOf('.') + 1,mySale.length()) + ""n";"

How do I get the Catch to not print "null" without losing the multi-error print functionality? Any and all help us GREATLY appreciated.

This program consists of the below two scripts, the "DKSaleCheck.java" is my problem child:
DKUnit6Ch15.java

import java.util.*; //Load all Utility Classes



public class DKUnit6Ch15 { //Begin Class DKUnit6Ch15



    public static void main(String args) { //Begin Main

        Scanner myScan = new Scanner(System.in); //Initialize the Scanner

        String myAmount; //Define a new Variable



        while(true) { //Begin infinite While Loop

            System.out.print("Please enter amount of sale in form $#.## ("q" to quit): "); //Print the text

            myAmount = myScan.next(); //Define a new Variable with the next user input



            if(myAmount.equalsIgnoreCase("q")) { //Begin If Statement (if the user entered "q" then do the following...)

                break; //Break the script

            } //End If Statement



            DKSaleCheck myCash = new DKSaleCheck(myAmount); //Define a new Variable and send it to the Constructor

            myCash.print(); //Print the Output from the Constructor

        } //End infinite While Loop



        myScan.close(); //Close the Scanner



    } //End Main



} //End Class DKUnit6Ch15

DKSaleCheck.java

    class DKSaleCheck{ //Begin Class DKSaleCheck



    int myDollar; //Define a new Variable

    int myCent; //Define a new Variable

    String myBad; //Define a new String Variable



    public DKSaleCheck(String mySale) { //Begin Method DKSaleCheck and receive sale as a string

        myBad = null; //Define a new Variable



        if(!mySale.startsWith("$")) { //Begin If Statement (if mySale does NOT start with a "$")

            myBad = "Invalid sale format missing "$" - " + mySale + "n"; //Fill the Variable with the String data

        } //End If Statement



        else if(mySale.indexOf('.') == -1) { //Begin ElseIf Statement (if mySale does NOT contain a ".")

            myBad = "Invalid sale format missing "." - " + mySale + "n"; //Fill the Variable with the String data

        } //End ElseIf Statement



        else{ //Begin Else Statement

            try{ //Begin Try Statement

                myDollar = Integer.parseInt(mySale.substring(1, mySale.indexOf('.'))); //Fill the Variable with the data if ONLY integers are detected from Index 1 to the "."

            } //End Try Statement



            catch(Exception myError) { //Begin Catch Statement (if the subString does not contain ONLY integers)

                myBad = "Invalid dollar format - For input string: "" + mySale.substring(1,mySale.indexOf('.')) + ""n"; //Fill the Variable with the String data

            } //End Catch Statement



            try{ //Begin Try Statement

                myCent = Integer.parseInt(mySale.substring(mySale.indexOf('.') + 1,mySale.length())); //Fill the Variable with the data if ONLY integers are detected after the "."

            } //End Try Statement

            catch(Exception myError) { //Begin Catch Statement (if the subString does not contain ONLY integers)

                myBad += "Invalid cents format - For input string: "" + mySale.substring(mySale.indexOf('.') + 1,mySale.length()) + ""n"; //Fill the Variable with the String data

            } //End Catch Statement

        } //End Else Statement



    } //End Method DKSaleCheck



    public void print(){ //Begin Print Method



        if(myBad != null){ //Begin If Statement (if the error variable is NOT null)

            System.out.println(myBad); //Print the String Variable     

        } //End If Statement



        else{ //Begin Else Statement

            System.out.println("$" + myDollar + "." + myCent); //Print the text

            System.out.println(myDollar + " dollars and " + myCent + " centsn"); //Print the text

        } //End Else Statement



    } //End Print Method



} //End Class DKSaleCheck

Scary Wombat had the best answer. I changed:

public DKSaleCheck(String mySale) {    

   myBad = null; 

   //rest of class

}



public void print(){ 

   if(myBad != null)

   //rest of class

}

to:

public DKSaleCheck(String mySale) {    

   myBad = ""; 

   //rest of class

}



public void print(){ 

   if(myBad != "")

   //rest of class

}

Worked like a champ!