Getting Around Global Variables

In many programming languages such as C or Pascal,most users have come across global variables.Like this C example:

    int GlobVar = 0;	// Global variable   void f(int x)		// Function to change variable.   {      GlobVar = x;   }

Java does not have such variables. However, there is a simple way to get around this, wrap the code in class declarations?like so:

    public class GlobalVariables {      public static int v = 0;      public static void f(int x) {v = x;}   }

[v] may be refered to with with: [GlobalVariables.v]

Note that the [static] keyword is used in declaring these classmembers so that they do not reference or operate on specific classobject instances. [final] may be used in declaration to “finalize” avalue, i.e., make it a constant. Related constants may be grouped like so:

 public class body {	public static final long text = 0xffffff;	// Fixed [final] used	public static final long bgcolor = 0;	// Fixed [final] used	public static long link = 0xff0000;		// Changeble: [final] not used	public static long vlink = 00ff00;		// Changeble: [final] not used}public class keyboard {	public static final String layout = "US";	// Fixed [final] used	public static final String keys = 101;	// Fixed [final] used}

Individual constants may be refered to with expressions like these:

 	int k = keyboard.keys;	long linkcolor = body.link;

Note if you’re using a class simply for packaging purposes (likethis), it really doesn’t make sense to create a new instance of theclass. So, you can declare a private constructor:

 	private Body() {}

A constructor executes when an instance of the class is created, butnot with a private constructor.

Share the Post:
Share on facebook
Share on twitter
Share on linkedin

Overview

Recent Articles: