Thread: Compile error for enhanded for loop

The second line is resulting in a Illegal start of type error.

	int totalAttributes;
	for( int value : attributesFinal ) {
		totalAttributes =+ value;
	}

I'm pretty sure that there are no misplaced or missing brackets in the code. At least as far as I can see:

abstract class Globals {
 
	//private class variables - default values
	private int[] attributesPrelim = {0, 0, 0, 0};
	private int[] attributesFinal = {2, 2, 2, 2};
 
	//set class constants
	int totalAttributes;
	for( int value : attributesFinal ) {
		totalAttributes =+ value;
	}
	public static int TOTAL_ATTRIBUTE_VALUES = totalAttributes;
 
	//public access methods
	public int getNum() {
		return attributesFinal.len();
	}
	public int getPrelim(int index) {
		return attributesPrelim[index];
	}
	public int getFinal(int index) {
		return attributesFinal[index];
	}
	public void addToPrelim(int index, int value) {
		attributesPrelim[index] =+ value;
	}
	public void setFinal(int index, int value) {
		attributesFinal[index] = value;
	}
}

What gives?

I'm not entirely sure how to copy text from Command Prompt, but the arrow points to the letter f in for. Like:

        for( int value : attributesFinal ) {
        ^

Thanks!

So I should create like a main method which initializes the variables, then?

Several problems here:

	int totalAttributes;
	for( int value : attributesFinal ) {
		totalAttributes =+ value;
	}
	public static int TOTAL_ATTRIBUTE_VALUES = totalAttributes;

First of all, you can not have a for-loop outside of a method body.

Next thing is, that "=+" is not a true operation. You probably meant to do "+=".

Then, if you really want to use "+=" you have to initialize "totalAttributes" to 0 or otherwise you get compile errors.

And finally, you probably want to execute the for-loop within a "static" block:

	public static int TOTAL_ATTRIBUTE_VALUES = 0;
	static {
		for( int value : attributesFinal ) {
			TOTAL_ATTRIBUTE_VALUES += value
		}
	}

I was actually gonna test whether or not totalAttributes would get assigned a default value of zero or not, but thanks for the info. Invaluable advice, all around!

Just so you know, the variable TOTAL_ATTRIBUTE_VALUES is NOT a constant at this point.
Its value can still be changed at any point in time.

If you want it to be a constant you need to do a little hack:

public static final int SOME_CONSTANT_INT = calculateConstantInt();
 
private static void calculateConstantInt() {
    return /* complicated calculation */;
}

For anyone who might be interested to see the end result

abstract class Globals {
 
	//private class variables - default values
	private static int[] attributesPrelim = {0, 0, 0, 0};
	private static int[] attributesFinal = {2, 2, 2, 2};
 
	//set class constants
	static int totalAttributes = 0;
	static {
		for( int value : attributesFinal ) {
			totalAttributes += value;
		}
	}
	public static final int TOTAL_ATTRIBUTE_VALUES = totalAttributes;
 
}

This way you still keep the variable totalAttributes. It will forever stay in your memory as a package-private static variable of your Globals class.

By the way, a class like this is heavily against the OOP idea. Instead you should make these variables private attributes and instanciate an object of this class. Either use the singleton pattern to access this object or keep it around as a private attribute of your controller classes.

Yeah, I kinda realize this at some level. This style of coding is probably how I would have implemented this in (a language like) Python. I'll give the singleton route a try, as I've been observing similar things before without giving it much consideration myself. I'm still not sure what the actual benefit would be though.

I tried googling for "controller class" but of course got the actual API class called Controller, while I'm thinking you're referring to a broader programming concept instead. Please do expand on this topic if you will - I'm all ears!

On a side-note: Working with the Command Prompt and jEdit has changed my Window keyboard setting from Swedish to probably English or some default setting. While I realize this can be fixed - should I expect this to be an ongoing issue going forward? While it doesn't affect my coding it makes it very hard to write on these boards...

What your "controller" classes are depends on your application.
There exists a certain programming paradigm which is called Model-View-Control (MVC). The idea is, that your classes are loosely divided into these 3 categories:
1) Model classes which contain attributes, information and management methods.
2) View classes which are used to visualize your data, create output and show it to the user or play sound.
3) Controller classes which create your models and the view, load data from disk, interprete user input, etc.

For every application these classes would look differently, but their use would always be similar. At first, this might look verbose or over the top, but I can tell you from my own experience, that this architecture works great for applications with a GUI, like some kind of editor or developement enviroment. Analyse your own program. Think what the entry-point is and how you can organize all your classes. Then think about how you want to distribute information (like your "globals") through this program.

Thats not quite how the singleton pattern works.
Here, take a look at this example, maybe it can help you:

Our singleton

public class Config {
 
	public static final Config INSTANCE = new Config();
 
	private int windowWidth;
	private int windowHeight;
	private String dataDirectory;
 
	private Config() {
		windowWidth = 0;
		windowHeight = 0;
		dataDirectory = "Resources/Data/";
	}
 
	public int getWindowWidth() {
		return windowWidth;
	}
 
	public int getWindowHeight() {
		return windowHeight;
	}
 
	public void setWindowSize(int width, int height) {
		windowWidth = width;
		windowHeight = height;
	}
 
	public String getDataDirectory() {
		return dataDirectory;
	}
 
	public void setDataDirectory(String dir) {
		dataDirectory = dir;
	}
 
}

How it is used:

public class Application {
 
	public void createApplicationWindow() {
		Config config = Config.INSTANCE;
		int width = config.getWindowWidth();
		int height = config.getWindowHeight();
 
		Window wnd = new Window(width, height);
		//...and so on
		Data data = new Data(config.getDataDirectory());
	}
 
}

Now, I would discourage this use, but it is simple and easy to implement.
Much better would be if you had a good information distribution strategy for your project.

For example:

public class Config {
 
	private int windowWidth;
	private int windowHeight;
	private String dataDirectory;
 
	public Config() {
		windowWidth = 0;
		windowHeight = 0;
		dataDirectory = "Resources/Data/";
	}
 
	public int getWindowWidth() {
		return windowWidth;
	}
 
	public int getWindowHeight() {
		return windowHeight;
	}
 
	public void setWindowSize(int width, int height) {
		windowWidth = width;
		windowHeight = height;
	}
 
	public String getDataDirectory() {
		return dataDirectory;
	}
 
	public void setDataDirectory(String dir) {
		dataDirectory = dir;
	}
 
}

public class Application {
 
	private Config config;
 
	public Config getConfig() {
		return config;
	}
 
	public void createApplicationWindow() {
		config = new Config();
 
		Data data = new Data(config);
		Window wnd = new Window(config);
	}
 
}

This way our window (view) and our data (model) will have access to our configuration because our Application (Control) will give them a reference.
This is more OOP then the singleton and is also easier to work with in my opinion.

But you should pick whatever strategy you prefer.

Well, I really can't see the difference between your singleton class and mine. Except that mine is defining variables inside the constructor, whereas yours only assigns the values once the constructor is invoked.

The other solution you suggest involves instantiating a new Config object every time the "global" variables av accessed, not? I don't see how that is more optimal than going the original route with an abstract class holding global class variables.

But since I'm still struggling with my singleton setup - does anyone know what is up with the Illegal start of expression errors I'm seeing?

You can not define attributes within a constructor, or any method for that matter.
Attributes of a class can only be defined outside of methods.

With the second approach you are not supposed to create multiple instances of Config. It will still be only a single instance for the entire duration of the program. The difference is, however, that it is created and managed within a Controller class, in my example this is the class Application.

By the way, I finally got the singleton solution working. Thanks Cornix!

//singleton class for holding global variables
class Globals {
 
	// setup singleton instance
	private static Globals singleton;
 
	int[] attributesPrelim = {0, 0, 0, 0};
	int[] attributesFinal = {2, 2, 2, 2};
	public final int TOTAL_ATTRIBUTE_VALUES;
 
	// constructor
	private Globals( ) {
 
		//set global constants
		TOTAL_ATTRIBUTE_VALUES = getTotalAttributes( );
	}
	private int getTotalAttributes( ){
		int totalAttributes = 0;
		for( int value : attributesFinal ) {
			totalAttributes += value;
		}
		return totalAttributes;
	}
 
	//public access methods
	public static Globals getSingleton( ) {
		if(singleton == null) {
			singleton = new Globals( );
		}
		return singleton;
	}
 
}

Consider this thread double solved, then.