Question

Possible Duplicate:
Why are static variables considered evil?

I have the habit of using static variables extensively in all my programs, especially when I am working with Android. I tend to use them because sometimes it feels so cumbersome to send 10 or more values via Intents. So, I just declare them as static variables and access them in the other classes easily by using the “dot” operator. Another reason for using static variables is when I am making a Utility class to be used throughout my application. Like the code I have given below helps me to use the variables in different activities.

Utility.java

public class Utility {
public static Facebook fb;
public static AsyncFacebookRunner fbAsyncRunner;
public static String[] fbPermissions = {"email", "read_stream", "user_birthday"};
public static final String PREF_UTILITY_FILE_NAME = "PrefUtilityFile";
public static SharedPreferences prefs;
public static Editor editor;
public static String access_token;
public static long expires;
}

I searched online for similar questions and came across this and this, but they do not seem to give a final answer to the issue. And in most of the places, I see conflicting opinions and hence am totally confused.

Is it a good programming practice or bad ? Should I be using it or not ?

Answer 1

You can replace all you static fields with a “Context” object which you can pass around or make a Singleton. It is possible to remove almost all your static fields away. Whether this is a good idea or not is up to you, but I wouldn’t assume that it has to be much harder to use instance fields.

BTW: I would suggest

• placing static fields/constant with the class or package which uses them
• treat static arrays as immutable if possible making them final as well.

---

You can use a non-static Context with

public class Context {
    public static final String PREF_UTILITY_FILE_NAME = "PrefUtilityFile";

    public Facebook fb;
    public AsyncFacebookRunner fbAsyncRunner;
    public String[] fbPermissions = {"email", "read_stream", "user_birthday"};
    public SharedPreferences prefs;
    public Editor editor;
    public String access_token;
    public long expires;
}

// pass to constructor as required
class UsesContext {
    final Context context;
    public UsesContext(Context context) {
        this.context = context;
    }

    public void method() {
        // can use context
    }
}

This allows you to create unit tests with multiple Contexts.

The only thing I would leave static are constants.