[Solar D]

Alright, forgive me if I've messed up in what I've attempted to write. I am trying to learn the very basics of Java and tried to do a very basic math... subroutine(if that is the right term).

Quote

public class main {
public static void calculator (String[] args) {
int y = 5;
int x = 2;
int z;

z = y*x;

System.out.println ("z");
}

} //basic math test

I save the file as Main.java to compile it like Netbeans 6.8 yells at me too.

When i attempt to run it i get:

"Main class wasn't found in JavaApplication1 project.

I have a feeling I may not have opened the right type of file to just mess around in.

If i want to start with a blank file with nothing to do the basics myself I should be going to New>Category>Java>Empty Java File?

If that is not the problem, then what in my noobish ways have I done wrong?

[m-e-g-a-z]

Close, you may want to look at this tutorial to help you with the basics.

//name of the class
public class calculator  { 
	//main method always has to be like this
	public static void main (String[] args) {
		int y = 5;
		int x = 2;
		int z;

		z = y*x;
               //print value of z, not the string "z".
		System.out.println (z);
	}

} //basic math test

[cfoley]

A main class in java is a class which has the main method. You can call the class whatever you want but the program always starts with the main method. This is probably what you want:

Save it in a file called Calculator.java

public class Calculator{
public static void main(String[] args) {
int y = 5;
int x = 2;
int z;

z = y*x;

System.out.println ("z");
}

} //basic math test

Beaten to it!

This post has been edited by cfoley: 15 June 2010 - 07:40 AM

[m-e-g-a-z]

@cfoley

I believe he wants to print the value of z not System.out.println ("z"); .

[Solar D]

Yes, as soon as I posted I realized I should switch the main and calculator labels.

And i see the error of my ways. I realized when i chose to "save as" calculator I didn't add the .java extension to the end(thought it would do that automatically). Also when i choose to "save as", does caps matter? I'm assuming it does? Just a habit i have from writing in MS Word.

Ex) Test.java = File name

public class test


Other than that it all makes sense now thanks!

[m-e-g-a-z]

Yes it does matter and it will not run, it will give you a java.lang.NoClassDefFoundError. Therefore the class name's case has to match the case you save it in. It is best practice to save your class with the first character starting with an uppercase.

[Solar D]

Alright thanks, good to know

As well, if i had:

int x = 6;
int y = 5;
int z;
z = x*y;

how would i write

system.out.println() to show the "y*z"?

So what i want is the sout to show

Quote

Z=6*5
Z=30

This post has been edited by Solar D: 15 June 2010 - 07:56 AM

[m-e-g-a-z]

Quote

how would i write

system.out.println() to show the "y*z"?

print out the results of the multiplication.
System.out.println (y*z);

prints out the String.
System.out.println ("y*z");

[cfoley]

m-e-g-a-z, on 15 June 2010 - 02:42 PM, said:

@cfoley

I believe he wants to print the value of z not System.out.println ("z"); .

Quite right. I hadn't looked past the main method error he had explained.

[NeoTifa]

Awww thanks for recommending my tutorial!

Also, I think it would be:

System.out.println("Z = " + x + "*" + y);
System.out.println(Z = " + z);

You would do this because you want to print a literal string saying z = but you want the value held by x and y, not the literal string "x" and "y", so you close the quote and concatinate the value to the end with a +. Hope that helps! ^__^

[Solar D]

Thanks! That was exactly what I was trying to do! Oh and PS I've already read that, very helpful.

As well one last question is there a way i can type larger sentences that take up more than one line in System.out.println ?

Such as how you can write a multi-line comment using /* */

[NeoTifa]

Awww thanks.

System.out.print(); You should know that from my tutorial. Just use a \n character for forced new lines.

[Solar D]

Ahhh okay, I must have forgotten or missed the /n part. Thanks, the makes things much less messy. And okay, I've been reading another book on Java as well.

So System.out.print() is for a general screen display where as System.out.println() can be used to specify more information separately, but will display it on the same line as System.out.print() is this correct? Sorry for all of the extremely basic questions.

[NeoTifa]

println just means that it automatically puts the carriage return in there for ya, as opposed to print which with multiple print statements would just run on and on on the same line until you type \n or \r. ^__^

[Solar D]

Oooh! Okay, makes sense. Thanks to everyone for steering me in the right direction.