.showInputDialog()

[Trey Cordova]

Okay, I am having a small problem and I am sure it is something easy to figure out.

I need to convert the null value that results from the user clicking "cancel" to a blank statement or "".

I have this code and something goes wrong to the point where I can't check for null values:

inputString = javax.swing.JOptionPane.showInputDialog(null, "Input any text.");

if (inputString.equals("null") {

inputString = "";

}

The statement works fine, but if the user decides to input "null" into the text-box the if-statement still runs as true. I understand why it runs as true. All I need to know is how to distinguish between the two (if possible).

[Darryl Burke]

That's not how to test for null.

// if (inputString.equals("null") {
if (inputString == null) { 

inputString = ""; 

}

And next time, please use the code tags to post code.

[Trey Cordova]

I think I am being a tiny bit confusing. I have used that condition before. The problem here is that when the value is saved in "inputString" it saves as "null". This would be fine, but the method that I have created is tearing apart the user's string that he/she put in and evaluating it. When the value is null (user clicks cancel) I need it to send the 'inputString = ""' through the method. But, if the user, him/herself, enters "null" in the input box, my if-statement isn't able to tell the difference.

Here is the code:

public static void main(String[] args) 
    {
        //Create a new string.
        String stringx = new String();
        //Assign stringx to the user-inputed string from dialog box.
        stringx += javax.swing.JOptionPane.showInputDialog(null, "Enter your string below:");
        //Run the walkString() method.
        walkString(stringx);
        
    }
    
    private static void walkString (String inputString) 
    {
        /**************************************************
         * walkString() evaluates inputString, user-inputed
         * string, by supplying its total characters,
         * digits, lower-case letters, upper-case letters,
         * and special characters.
         **************************************************/
        
        if (inputString == null) {
            inputString = "";
        }
        //Use xxxx.length to calculate all the characters in the user's input.
        int length = inputString.length();
        //Assign char to break string into single-lined characters later on.
        char c;
        //Assign integers to count the amount of digits, lower-case and upper-case letters.
        int digits = 0;
        int lower = 0;
        int upper = 0;
        
        //For loop will go through each individual character to determine its kind.
        for (int i = 0; i < length; i++) 
        {
            //Breaks "char c" into single-lined characters.
            c = inputString.charAt(i);
            
            //Counts digits.
            if (Character.isDigit(c)) 
            {
                digits ++;    
            }
            
            //Counts lower-case characters.
            if (Character.isLowerCase(c)) 
            {
                lower ++;
            }
            
            //Counts upper-case characters.
            if (Character.isUpperCase(c)) 
            {
                upper ++;
            }

            
        }
        
        //Assign "int special" to calculate for leftover characters like special characters/spaces.
        int special = length - (lower + upper + digits);
        
        //Print out results.
        System.out.println("Input:  [" + inputString + "]");
        System.out.println("\tTotal Characters: " + length);
        System.out.println("\tDigits: " + digits);
        System.out.println("\tLower-case Letters: " + lower);
        System.out.println("\tUpper-case Letters: " + upper);
        System.out.println("\tSpecial Characters: " + special);
        
        
    }

}    

In the end, if the user clicked "cancel" the result with the condition that you suggested returns "null" and it evaluates the word null. I need it to evaluate "".

[Maneesh Godbole]

Trey,
Welcome to the Ranch.

Your question would suit better on the UI forums. Moving thread.
Please do take out time to go through http://faq.javaranch.com/java/HowToAskQuestionsOnJavaRanch

[Trey Cordova]

Will do, Maneesh.

[pete stein]

Trey Cordova wrote:I think I am being a tiny bit confusing. I have used that condition before. The problem here is that when the value is saved in "inputString" it saves as "null". This would be fine, but the method that I have created is tearing apart the user's string that he/she put in and evaluating it. When the value is null (user clicks cancel) I need it to send the 'inputString = ""' through the method. But, if the user, him/herself, enters "null" in the input box, my if-statement isn't able to tell the difference.

Yes, your if statement will easily tell the difference. Darryl isn't suggesting to test

if (myString == "null") {

but rather

if (myString == null) {

and there's a big difference between the two. His suggestion will work just fine for you if implemented.