Reading Properties File

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Transcript

Hello, guys, welcome back to the next one. And this one, we're gonna see how we can read the properties files in Java. So it's gonna be really important when we want to store some data in external files. And we want to utilize them in our programs in Java. So it's gonna be really quick when it's pretty easy in Java. So let's just take a quick look.

I have a class defined already, which is reading properties, nothing else, just a main method inside it. And now we're going to see how we can do that. So the first thing we want is what Java provides us is a properties class. So we want to create an object for that. So I'm just creating an object properties prop equals to new properties, and parenthesis and semicolon. Now it gives me error, which is not basically it's gonna ask me to input some statements, right?

So I'm going to import properties from Java util. So be careful guys. That multiple properties classes from other open source sources as well. So I'm just gonna select the one from Java dot util. And the one I imported. It's available right now here.

So what is this properties class, this is the properties class, which is already in built within Java. And that helps Java to understand what is a properties file. Basically, it does not read the file. To read the file, we have a different mechanism. And we're going to do that right now. But it helps our understand how the properties file is interpreted.

So how we define the properties files is one convention, and then it just loads all the values from the properties file so we can utilize them. So let's go ahead and see that. So let's see how we read the file. In Java. We can read a file utilizing the class called file input streams. I'm going to save file input stream stream.

And I can just say Fs. So basically, this is a class and I'm creating an object for it. I'm just gonna say Fs equals to new. And control, I'm just gonna say, file. input stream, right? And it accepts a file, right?

So basically, it needs to know what the file is. So that's about it. So this file input stream is the class that's again provided by Java, which actually reads the file. So since it reads the file, it needs to know where the file exists, right? So let's do one thing. We don't have a file right now, let's go ahead create a file, so we can read it.

So I'm gonna just create the file inside the same package. So right click, and new, and I'm just gonna say a file. So there are few things that's important. So I'm just going to say test dot profit. These, this is the key guys, this is really important. So any file that we want to read utilizing the properties class, we want to name the file anything but we want to put the extension dot properties, this is really important.

If it doesn't have the dot properties extension, it's gonna have issues and reading and understanding the file. So I'm just gonna go ahead and click Finish. It is an empty file right now. And let's see how we define the file. So we can define the file in the key value pair. So I'm gonna say name, maybe, let's call it and I'm going to say, course, I'm going to say Java.

So if you notice, it's pretty straightforward. What this is, it's a key, which is named equal to value, which is my value. So any data that we want to specify should be value. And the key is going to be something with which I'm going to be accessing the data inside my code. So the value that I want to read is the lead score ID. And the key is name.

That's a key value pair. simples straightforward thing, and course is Java. So if I want to use Java in my code, I'm just going to call the key from my code, and I'm going to get this value. The advantage of this is, let's say if something changes, this becomes a Java. Instead it becomes Python or something like this. Maybe Java plus Python, maybe let's do something something becomes right.

So what happens is we don't have to change the code at all. This is the main advantage that we can just change the code here, not the code, we can just change the data here in the properties file. And we can still read the same key, right? And we will never have to change the code in my in the classes, right? So this is really important. It's very advantages.

So now let's get the file paths. I'm just going to right click On this, I'm going to go to properties. And location, I can just copy everything. So I'm just going to copy this, click OK. And let's define a variable here string path equals to this, and semi colon. If you're working on Windows, your path is gonna be different. In Java, always make sure that you have double slashes.

It's really not needed in math. But in Windows, you'd really need it. So just make sure you have it. So this is the full path, I can just provide the path up here. Now I just provided the path. And that's pretty much it.

Now it shows me something else to add exceptions and all those things. So because we are not catching the exceptions in a try catch block, it'll ask us to add throws declaration or something. So we can just do that. Instead, we can just do IO exception and we're all good. So I can remove the ones that is not used. All right.

Now, what else I need to do, I need to do prop dot load. This is the method that's provided by properties file. And if you notice, there are multiple overloads of the same method. And one of them accepts input stream, which is what we are using to read the file. I'm gonna use the first one, and call the input stream. Let's provide Fs.

That's the object we created here, right? Now, it's gonna actually read the complete file inside the memory. So how we can utilize it, we can just utilize it utilizing them using the name. So let's see. So and I'm going to say crop dot get property. So when I say get property, do you see here it says cranky?

It accepts it expects a key. So I'm going to put the key as let's say name right? Now, and let's see what it prints. So let's run the code, right click run as Java application. And it prints. Let's call it.

So do you guys see that that I have the value, let's coat it in front of name, and I get it. So same way I can get the next property is well, next property was codes. So let's run the code again, run as Java application. And it prints Java plus Python. And let's call it both. So let's say now the data has changed, right?

Let's say let's remove this. And the data is this. So we don't have to make the change in code, we can still run the same code, and I'll get the data where I change in my data file, which is a properties file. This is the advantage case, this is really a huge advantage that you don't have to change the code. You can just modify the data and it's going to be reflected in our code. So that's about it.

Guys. That's pretty much it to read the properties files and Java, I would say just download the code for reference. And let me know if you have any questions. The most important thing is practice, guys, please never forget that it's really important. That's the only way you want to learn

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