Use Javascript to upload csv file and chain replace method

Uploading the csv file was the easy part thanks to this code. (Just make sure you have appropriate code to display it since the author just uses console.log.)

Once the csv file was uploaded, my goal was to select certain rows and then, from those rows, select certain fields to display. We'll start with how the code to upload the csv file works.

Uploading the csv file:
Mounir Messelmeni's processData(csv) method takes the csv file you select as an argument and stores it in a variable as a string using split(). Once the string is appropriately split, the code then uses nested for loops to first split each record and then store each record as an element of an array. (You'll notice my code is slightly different regarding the separators I used.)

Regexp patterns
My problem was that I needed to access the individual fields within the records. That sounded a lot like accessing elements in an array, except I wasn't dealing with an array but an element in an array. Naturally, my first thought was to make each element its own array so I could access the fields as elements within the new array. You've probably already guessed the problem. When I created the new array and assigned an element to it, that didn't split anything up. I just had an array with one element.

I then considered separating each char and storing certain ones into an array and that array would then become an element in another array. That made me tired thinking about it. Plus, I still had the issue of figuring out how to target certain chars.

I also thought about saving the array element containing a record as a string, separating the string, and based on the separation, creating elements for an array. But I finally decided it was just easier to search for patterns. I am not claiming this is the best way, just that it is one way.

My code starts by storing lines.toString() in var x. I then create two patterns. (The csv file only contains 2 fields per record. For demonstrative purposes, text in both fields will be replaced.)

I also created an empty string, newstr which is then assigned the variable "x" with chained replace methods. The value of newstr becomes the value of the element with the id "list". I include an alert to show you the value of x before so you can compare that with the replace values.

The full code, including the csv file I used, is here.

Java command line

It's a basic concept, but it threw me at first. How do the command line and a Java program you wrote in an IDE interact?

First, the command line:
     a) Save your java file in a text editor as YourFile.java. Read this for more details.
     b) Get to the command line. If you're using Win8, for example, go to the Start menu and either type in "cmd" or use search and type in "command".
     c) On the command line itself, first change to the directory in which you saved your file. (See page I referred to above.)
     d) Set the path. The page referred to above addresses this but it didn't work for me. This is what worked for me. Proceed with caution.
     e) Compile by entering this at the command prompt - javac YourJavaFileName.java
     f) Run the interpreter by entering this at the next prompt - java YourJavaFileName command parameters
     ex. java InvestmentFile calculate .04 10 5000
    //calculate is the command;
   //.04, 10 and 5000 are the arguments

Entering the command: Just make sure the user knows which command to enter in the beginning and follow up in case they still enter the wrong thing.

if(user enters right command)
{//code}
else
{//tell them what to do or use a try-catch block instead}


Now, how do the parameters in the methods connect to the arguments on the command line?

Let's assume in the example above that .04 represents the interest rate, 10 represents the number of years and 5000 represents the amount invested.

Let's say you have a method that has these 3 things as parameters. Here is how you'd normally write the method:

public double calculateROI(double rate, int yrs, double money)
{
    //code
}
 But for the command line, here is how you write the method:
public double calculateROI(args[0], args[1], args[2])
{
    //code
}

Look familiar? Yes, finally, we see a point for those args in the main method.  Here is where exception handling comes in. If the first parameter in your method is the interest rate and, obviously, you want the first argument written on the command line to be the interest rate, you have to account for handling the error of someone not doing that. Otherwise, if the number of years is entered as the first argument, you clearly won't get the right result.

This isn't unlike dealing with parameters and arguments normally. Just make sure the user enters the arguments in the right order, after you've made sure they've entered the right command.

Xojo: Creating a report from a listbox

Initial disclaimers: The code presented here is not my own. My goal is to fill in some of the blanks when it comes to learning to create a simple report from a listbox in Xojo. There isn't a lot about Xojo out there and I feel the more information that is presented in various formats, the more likely people are discover the beauty of Xojo (formerly known as RealBasic or Real Studio).

Step 1:
Put something in the listbox! The code I used comes from here. I imported a csv file so I didn't need the code to write to the listbox, just to read it. As a result, I just skipped the write portion of the code. I also added a button called "Load" to the window and put this code under the Load action event.

Step 2:
Watch this video and read the Examples folder under Printing and Reporting. That's where the rest of my code came from. The Examples folder is in Xojo and you'll see it on the sidebar when Xojo first opens.

Step 3:
Under App, choose the appropriate window. Otherwise, you won't see anything. It's a small step and one I overlooked. I drove myself nuts trying to figure out why nothing was displaying as planned.

Step 4:
As one of my Xojo friends explained, if you have a Mac, you will be able to preview the report as a PDF. Pretty cool since that's mostly what you'll want to do - preview the pdf, email the pdf. But in Windows, that functionality isn't present and, unfortunately, it's still a work in progress in Xojo itself, although, high up on the to-do list. There are a couple of options, besides just literally printing out the entire report.
      a) Use the Dyna plugin but it's not free. However, if you're creating an app to make money and not just for fun, it might be worth the cost. Like the Xojo license, it's not unreasonably priced.
      b) Create your own pdf framework. This is outside my realm of knowledge.
      c) Use OneNote. It came with my laptop on Windows 8 and I accidentally discovered that while I can't view the report as a pdf, I can view it in OneNote and that has the same effect. This isn't the prettiest report but it gives you an idea of what you can do. You'll see the Address and Subdivision fields from the report that are the column headings here. ***Note that the DataFields in the Inspector should use the same name as the original fields. The CSV report I used named the fields, "Address" and "Subd" and those are the names in the DataFields. In the text property in the Inspector, you can enter whatever text you want.

You can see how I put all the code together in GitHub. If anyone feels it would be useful, I will write down step-by-step what  I did. It didn't seem necessary as I wouldn't have really added anything to the sources cited above. So unless I hear otherwise, Happy Reporting!

What I love about Xojo - Part 2: GUIs, Multiplatform, Databases

In the first part, I loved the fact that Xojo's online book explained caching. So simple yet so important and often overlooked by instructors. It made me think that the people behind Xojo really thought things through in the development process.

The other reason Xojo(fka RealBasic, Real Studio) is so lovable is that it makes difficult things simple.

While I have a thing for C#, creating GUIs in Windows Forms is a major pain. With Xojo, you drag and drop. Seriously, that's it. Drag and drop and go to the Inspector to set values for the properties. Then you can actually work on your code instead of spending a ton of time coding for the GUI. Listbox? No problem! Labels? No biggie!

Then there is the real reason for Xojo's existence in the first place - multiplatform. Do I love Apple? Not really. Am I planning to learn Objective-C? No. I'm a Windows kind of girl. But now I want to create an app for a friend who happens to use a Mac. What's the answer? Xojo. Write it in Xojo and it can be used on Windows, Linux or Mac. (If I ever find time to finish said app, I'll write about that.)

Last, but not least, the database. It's a mistake to think you can become a real programmer without loving the database life. SQLite is part of Xojo and you can actually create the database in Xojo using the insert menu. Feel free to do it programmatically, too.

I think Xojo is a great business solution for companies/individuals who have limited resources in terms of being able to write code for multiple operating systems and maintain that code. You do have to pay for the license to deploy your app, but you can build it for free to see how you like Xojo. The license is not unreasonably priced either. Check it out here.

Java - equals vs. ==

Finally, I found an article that explains this in terms that are understandable.

In a previous post, my explanation for C# reference type vs. value type is the difference between your painting ,which is an original masterpiece, getting destroyed (no more painting for anyone) and your painting, which is a print, getting destroyed (more copies can be made).

However, I still had trouble understanding the concept that underlies the issue here of when to use equals method instead of the == operator.

Here's a synopsis of the article:

1. == compares memory addresses.
2. equals, as inherited from Object, does, too.
3. If you want equals to compare data, then you have to override the equals method inherited from Object.

So that explains not only the difference (or similarity, as the case may be) between  == and equals. It also explains that what is being compared is either the address or the data. Hence, in the example in the article, A == C //false because they have different memory addresses. But A.equals(D), once the equals method is overriden, is true because the data is being compared. Thank you, Kurt Mammen!

What I love about Xojo - Part I - Caching and optimization

Caching - Have you even done a programming exercise, in any language, and done something like this?
      int x = array.length
      int average = 10/x

Have you wondered why you didn't just do this?
     int average = 10/array.length

Because they both work, but one requires more lines of code. Aren't we supposed to use as few lines of code as possible (within reason)?

The answer is explained in Xojo's book, Introduction to Programming, by Brad Rhine. On pages 89-90, Mr. Rhine explains that if you use a built-in function and you're using a loop, for example, the entire function has to run every time the loop iterates. If you assign the function to a variable, in other words, if you cache it, your app will speed up by accessing the value of the built-in function instead of running the function each iteration.

Seriously. To date, I've taken several programming classes and done some self-teaching and never has this been explained. See also this article that goes into a lot more depth.

Xojo gets the first thumbs up from me for explaining a common concept that should be explained in every intro class for any language.

Break out of a sentinel-controlled loop in Java/C#

The issue is the same in Java and C# . To exit a loop with a sentinel-controlled value, you need a break statement.

Example:
while(someValue != "Q"){
      //code for loop to execute while sentinel value not entered
      if(someValue.equals("Q"){
             break;//MUST USE THIS OR YOU WILL LOOP FOREVER
}

I think MSDN does a much better and simpler job explaining break. But I did manage to find some Oracle documentation that included code examples here.

In general, I am finding any documentation on Java to be spotty and not well written in the sense of not providing a substantive explanation with code examples. (Sorry to all the Java die-hards I offend.) In this case, you can see that MSDN uses one sentence to explain the break statement while the title of the Oracle documentation will make it difficult to even find this in a search using keyword "break".

The moral of the story: Java is a competitor to C# so they are very similar. If you can't find info on your Java issue, you might find it in MSDN and be able to apply it to Java.