Nighthawks Java Tutorials (Look here if you need to learn Java!)

Throughout this thread I will be posting a series of Java tutorials. Feel free to skip through the posts that have been made in-between the thread. If you have a question, please quote the section you have a question about, and than I will do my best to answer it for you.

Before we begin:

I assume....

-You have a basic knowlege of what java is
-You know how to perform basic tasks such as navigating throughout your computer and web browser
-You know how to download and install software
-You can type properly
-You have a decent enough amount of common sense
-You know basic math (adding and subtracting) and you know advanced math (square roots and absolute value, etc.)

Now that we've gotten this out of the way we can begin your course in learning Java!

Nighthawk0973 wrote:Before we begin:

I assume....

-You have a basic knowlege of what java is
-You know how to perform basic tasks such as navigating throughout your computer and web browser
-You know how to download and install software
-You can type properly
-You have a decent enough amount of common sense
-You know basic math (adding and subtracting) and you know advanced math (square roots and absolute value, etc.)

Now that we've gotten this out of the way we can begin your course in learning Java!

Just like the "For Dummies" books.

Programming in Java isn't as simple as opening up notepad and creating a text file. You need special tools that not only let you meet the bare requirements to be able to program Java, but will even help make your Java work become easier.

The first thing you're going to need to have is what's called the compiler. A compiler is a special program that turns code that you can understand, and turns it into code the computer can understand. This process is called compiling. The compiler we are going to be using and the compiler that most people use when they program Java, is the JDK. (Java Development Kit) To get this program you need to go to the Java SE downloads page. Java SE is short for Java Standard Edition. You can find the Java SE Downloads page here:

http://www.oracle.com/technetwork/java/javase/downloads/index.html

Find the spot on the page that says 'Here are the Java SE Downloads in Detail:'. Find the button that says 'JDK' and click the download button. You'll want to download the most recent version of Java. Currently this is Java 7.

Did You Know:
Java uses 2 different ways of listing the version. In most cases it will be 'Java version <version> update <update>'. But in file/folder directories you'll see the version listed like this: 'Java BigVer.Version.Update'. If it's Java SE 7 update 26 it will be: Java 1.7.26. So why all the confusion? Well there's another version of Java that we won't be covering in this series called Java 2. I don't use it and probably never will. I don't know any major companies that use it but I know it's slightly different than Java, and you have to download different software. Java 2 version 7 update 26 would look like this: Java 2.7.26. Get it now?

You're going to need to follow a few instructions and agree to a license agreement or two. Next you'll wait for an installation bar and you'll finally you'll be done.

Now that we're done with this we're ready to program Java! ...Kind of. While we could just start typing all our code in notepad, we'd have to compile each file separately, and we'd have to do a whole bunch of other unnecessary junk and this would really get annoying after a while. Especially since I'm not teaching these steps. Instead we need to download a special software called the IDE, or Interrogated Development Environment. It's basically a special text editor that's built to make Java programs. There are many out there, obviously enough you can find these editors by googling their names. Populars IDEs include Netbeans, which is available on Oracles website; JCreator, which was my first IDE; and finally Eclipse, the IDE I use and that I'll be giving a link to, and the only editor that I didn't get Firefox giving me spell check errors on. Here is the Eclipse download page:

http://www.eclipse.org/downloads/

Download this software and unzip it, than place the folder you get in your program files folder and send a shortcut to your desktop. Run this program, click the 'x' on the start page, and than mess around with it to customize your interface. I like to remove the small panels on the right, and keep my code panel, package explorer panel, and debug panel in my window because that's what I use.

Notice:
You don't have to use Eclipse. This is my personal preference, but the choice is yours. No matter what IDE you use, they're all working together with the JDK to compile your code. This means that you will be able to follow the same code that I do, even if you're not using Eclipse.

Congratulations! You have successfully setup your computer so that it can create Java programs! You are now ready to begin programming in Java.

David B wrote:

Nighthawk0973 wrote:Before we begin:

I assume....

-You have a basic knowlege of what java is
-You know how to perform basic tasks such as navigating throughout your computer and web browser
-You know how to download and install software
-You can type properly
-You have a decent enough amount of common sense
-You know basic math (adding and subtracting) and you know advanced math (square roots and absolute value, etc.)

Now that we've gotten this out of the way we can begin your course in learning Java!

Just like the "For Dummies" books.

lol yes that's where I got the inspiration to do so. This is set up more like a book, and since I know dummies books a lot, that's kind of what you'll see. Such as 'Did you know...'

Must resist...ugh tried can't resist.

I want to learn Java do I qualify?

Nighthawk0973 wrote:
-You have a basic knowlege of what java is//URRR coffee? Oh wait an island.
-You know how to perform basic tasks such as navigating throughout your computer and web browser// Duh you click da button thingy on da rat.
-You know how to download and install software// Oh yeah you know it. hehehe
-You can type properly// 0f (0Ur53
-You have a decent enough amount of common sense// *oh no my bro is going to be eaten* * Time to play some Starcraft*
-You know basic math (adding and subtracting) and you know advanced math (square roots and absolute value, etc.)
7 -5 = 2.000001. Yes my abs are absolute, but no I don't have any square looking roots. =\
Now that we've gotten this out of the way we can begin your course in learning Java! You bet cha.

On a serious note: What kind of things will you be doing tutorials on; or are you just doing a general scope of Java?

If you've ever seen a tutorial on a programming language, you've obviously figured out what the phrase 'Hello World' means to programmers.

If you haven't than I'd better tell you. Hello World is the most common program people use to teach other people Java with. (for their first program) You learn how to print some basic text on the screen, and of course, your text is always "Hello World!".

So let's get started yet. The first thing we need to do is open up our Java editor; if you're using Eclipse go to File->New->Java Project. Name your project and leave everything else alone. In the 'Package Explorer' view, expand your project until you've found the 'src' folder. Right click the src folder and choose Add->Class. This will create a new Class file. A class file is what makes up your program. While the actual source code files you read are called .java files, the computer understands the .class. Name your class something that's on your mind like Doughnuts, and than click continue. You should get a bunch of code. Delete all this since it'll probably give you a headache without a proper explanation. Next write the following in the text box:

Code:


//This is a comment!


As the code says, that is a comment. You can start comments to define/explain special sections. Trust me they come in handy. You can write comments anywhere, but after the '//' the comment begins, and the rest of the line (not the code before it) is considered a comment, and will become green, and is "Ignored by the Compiler". This means the comment won't give you error messages.

Now let's get back to some more coding. To start our hello world program (you can delete the comment) you will need to type this: (remember to pay attention to my comments that I leave in the code for little bits of information that are very important. You don't need to write the comments)

Code:


public class Doughnuts{
/* the 'doughnuts' part needs to reflect the name of your class file at all times
Please note that this is a multiline comment starting with the slash-star and ending with a start-slash */

}


So let's take a look at this code step by step:

the public keyword is a keyword that will make your program 'public'. This means that it can be read and used by other programs. This will become more useful later on. Now let's take a look at 'class', this basically means we're writing a class file at the moment. Finally the 'Doughnuts' is basically your class game. Now we branch out the code with '{' and '}'. These are called 'Curly Braces'. Everything inside your curly braces is inside your class. Please note that Java ignores white space, so that means that:

Code:


public class Bob{


}


is the same as

Code:


public class Bob
{


}


how you organize your code is up to you!

Next let's add a few more things to your code:

Code:


public class Doughnuts{

  public static void main(String[] args){

     
}
}


Notice this code branches out into curly braces too. There's not much point in explaining too much in deft when it comes to what this is, you can just use my small definition, you'll learn about how it works later on as you learn more keywords, without me even teaching you it directly. So basically this is your 'main method'. This is essentially the launching point for your application. So whenever the compiler runs a program it first looks for the main method first. All right, so now that we've done this we can begin writing code inside of our main method.

Code:


public class Doughnuts{

public static void main(String[] args){

    System.out.println("Hello World!");
}

}


Before we go off and run this code, let's take a quick look at what this does and how this works.

Well, you know what it does, prints 'Hello World', on the screen. But how about we go into detail on how it works.

To start off we call on something called System. Then we tell system to make an output, AKA, .out. Now we tell it to 'println'. This stands for Print Line. There is also a command called 'System.out.print', and it basically just does the same thing, except println prints us the text and than wraps everything to the next line. Next we have the two parenthesis. Inside the parenthesis we put stuff. This stuff is called parameters. You can separate multiple parameters with a comma. So what is out parameters? Well they're basically variables. But that doesn't mean they're numbers. There are many variables in java, these variables are called 'string' variables. They are a string of text, so basically just text. String variables always have two quotation marks with the contents of the string in-between. So we'll make our string equal to "Hello World!". Finally we add a semi-colon ( at the end of our line. Anything that doesn't make curly brackets after them will end with a semicolon. NOW you can run this program and see if it works! If it doesn't work follow the debug messages and try and fix it!

Post Work:

(Post Work is basically homework to make sure you understood the lesson. It's called post work because you post the answers on the forum. Copy the below code into your post and than fill in the answers. This is optional but recommended.)

Code:


Post Work - Tutorial 2 - Hello World Program

1. What's wrong with the following code?

public class Turkey{

public static void main(String[] args){

System.out.println("Eating turkey while programming in Java is fun!")
}
}

Answer:




That's all for this lesson make sure to check out the rest of my tutorials when they come and don't be afraid to ask questions!

legolizard wrote:Must resist...ugh tried can't resist.

I want to learn Java do I qualify?

Nighthawk0973 wrote:
-You have a basic knowlege of what java is//URRR coffee? Oh wait an island.
-You know how to perform basic tasks such as navigating throughout your computer and web browser// Duh you click da button thingy on da rat.
-You know how to download and install software// Oh yeah you know it. hehehe
-You can type properly// 0f (0Ur53
-You have a decent enough amount of common sense// *oh no my bro is going to be eaten* * Time to play some Starcraft*
-You know basic math (adding and subtracting) and you know advanced math (square roots and absolute value, etc.)
7 -5 = 2.000001. Yes my abs are absolute, but no I don't have any square looking roots. =\
Now that we've gotten this out of the way we can begin your course in learning Java! You bet cha.

On a serious note: What kind of things will you be doing tutorials on; or are you just doing a general scope of Java?

lol try not to spam this thread to much. Especially with those lol faces.

Also if that was on a serious scope to begin with I would say you don't qualify to learn Java, you need to take a spelling class first.

Finally, I'm teaching from the ground up, Hello World, Variables, If Else Loops, basically like a tutorial series that gets you started learning Java.

Wow! This thread has grown alot since I last looked at it!

mainly because my tutorials are so large. XD

I'll make some today if I get time. Just got done with school. (12:33, quoting DB in the future "I envy your situation" )

Nighthawk0973 wrote:mainly because my tutorials are so large. XD

I'll make some today if I get time. Just got done with school. (12:33, quoting DB in the future "I envy your situation" )

I still envy your setup.

First of all, don't freak out because it's math. You'll actually like this because we're telling the computer to do the math for us. Now, onto the lesson!

This is going to be shorter because I'm not explaining as much. So anyways in this tutorial we're going over variables. As you remember, parameters store the values of different variables in functions. Of course you have to write these values. But what if you had a rpg game. Well you need to have constant stat variables that you can add and subtract in order to get damage amounts and whatnot. So naturally this means we'll need variables. In fact you probably won't find a (good) java program,, or program in general, that does not use variables. So let's get started. We'll be making a simple calculator... kinda. The first thing we need to do is create the variables. We can create variables like this:

Code:


vartype varname; //SEMICOLON


the code should be self explanitory. Now we have this variable, but let's give it a value. To do this is pretty obvious:

Code:


varname = varvalue;


That's all we do, variable equals variable value. We can also do the same thing we just did all in one line:

Code:


vartype varname = varvalue;


What way you do depends on your program. Let's go over some real variables types:

Code:


example:
VarType - Quick Description of Variable Type
real variables:
int - An interger or whole number
double - An int, but it is a decimal or 'Real Number'
String - Text, in any size. If you type \t in this it will make a tab in your text and \n is new line.
boolean - True or False Value. Can be defined as 'true' or 'false' or 'boolean mybool = x > 2' than if x is greater than 2, the boolean will be 2, if not it's false.


So that's easy right? We can print out our variables value with this command:

Code:


System.out.println(varname);


Finally we have math. It works like this:

Code:


int fnum = 25;
int snum = 2;
int answer = fnum + snum;
System.out.println(answer);


this program should print the answer of 25 and 2, which is 27 if you don't know for some weird reason. You can also replace the plus sign with a '-',(minus) '*', (multiply), '/', (divide) or '%' (remainder of division problem) symbol. So that's pretty much all I wanted to teach in this lesson I hope you guys enjoyed!

Code:


PostWork

1.) What will this program do?

public class Program{

  public static void main(String[] args){

      int num;
      int divnum;
      System.out.println(num/divnum);
}
}


nice

Also, it's a bit off topic but I like the new cursor DB. Nice job. I'll make sure the thread get's back on topic when the next tutorial comes out.

Hey guys welcome to your forth lesson of learning Java!

Now, it's nice and all that you can input the values of variables. But sometimes you need the user to input these values, such as when you want to type in a username for something. To do this, you need Scanner. Let's get started.

To start using scanner we need to do something called importing it. To import something we need to first learn about what we're importing. To do this you need to locate where your java is. Find the jdk folder, and than choose to open the 'src' .zip folder. In here you'll find all these different folders, and in these folders, you'll find .java files. Don't open them because they'll give you a headache. But if you go to the java/util folder, you'll be able to find a file called 'Scanner.java'. This is java code that turns 2500ish lines of complicated code, into some simple code we can use. So let's learn how to import this. Before you declare your class, write your imports. In this case, write:

Code:


import java.util.Scanner;


This will import Scanner.java. Assuming you have an ounce of common sense in you, you should be able to figure out how this works. Each '.' created significates a 'backslash' until you get to your main folder. Everything in java.util, or another section of available java imports, can very easily have other imports that do similar things, which is why they would be categorized in the same folder. So to import an entire folder from the java 'src' we would do this: (in this case importing java.util)

Code:


import java.util.*;


This will import scanner, and a bunch of other util stuff.

Caution!
Even though this statement is done outside of our class decleration section, and is not in a method, we still add a semicolon to it.

Alright so now we can import Scanner. If you don't know already, Java is OOP (Object Orientated Programming) and you're about to see why.

So after importing scanner, we need to use it. Let's start creating the program we're making in this lesson. Import scanner, and create a basic class. Than make our main method and create a string called 'userInput'.

Here's what it should look like:

Code:


import java.util.Scanner;

public class Scanner{

    public static void main(String[] args){

    String userInput; //NOTE: Java is case sensitive. String does not equal string.
    /*
    Something you should know:
    Java uses the following mathematical equality/inequality operators:
    == (equal to)
    != (not equal to)
    >= (greater than or equal to. Notice that the greater than sign goes first)
    <= (less than or equal to. Notice that the less than sign goes first)
    > (greater than)
    < (less than)
    */
    }
}


Alright now we need to create what's called an object, to use Scanner. This is like creating a variable. The variable type is 'Scanner', variable name is whatever you want. For the value you need to type 'new Scanner(System.in)'. System.in is for System.input. Your code should look like this:

Code:


import java.util.*;

public class Scanner{

public static void main(String[] args){

String userInput;
Scanner SO = new Scanner(System.in);

}

}


Now we need to get the value of our String, with Scanner. To do this we make the strings value 'Scanner.nextLine();'. If you're getting input for a 'double' or 'int' you must use 'Scanner.nextInt();' or 'Scanner.nextDouble();'. Finally use System.out.println to print the value of the string.

Code:


import java.util.Scanner;

public class Scanner{

public static void main(String[] args){

String userInput;
Scanner SO = new Scanner(System.in);
userInput = SO.readLine(); //Note how we replaced 'Scanner' with our Scanner Object.
System.out.println(userInput);

}
}


That's all there is to scanner!

Code:


Post Work

1.) Create a program that asks any question you wish, using Scanner to get the input of your string/double/int.


Your tutorials are really coming out nicely! I would really like it if you made more later on!

I will ;D

Nighthawk0973 wrote:I will ;D

Thanks!

I would like to learn java but I have no idea how to use it or even were to download a scripting version.

Beachbum111111 wrote:I would like to learn java but I have no idea how to use it or even were to download a scripting version.

Along with you, Arty-FishL is beginning to discover the awesomeness of the PLCF, and it is my understanding that this is one of the languages that he is pretty good at. You may want to send him a PM just to make sure.

...did you read my tutorials? The first tutorial is about how to set up the Java Development Kit and Eclipse so that you can program Java applications, and the other tutorials help you learn. Plus there is a series of tutorials linked on the forums, if you aren't satisfied with 87ish tutorials on there than idk what your expecting. And trust me, it's NOT as easy as alice ;D

Good luck! (search the forums! top right!)

Oh, well there is a good point that I have failed to bring up before! Why don't you just ask nighthawk for an explanation that uses perhaps a little more English?