Here is an Android example of how to share variables through out your activities and your project. There is many ways including preferences, extending from a base activity or using  a database to share variables. I like this one because it can be accessed through the whole project and it is easy to implement. The down side is that the variables are only available through a session. For example if the user restarts the application then all the variable will also be cleared. So they can be viewed as session variables.

GlobalState Class:

-Note this extends Application

import android.app.Application;

public class GlobalState extends Application{
	
	 public File sd = null;
	 boolean refresh = true;
	 pictureData [] picturemarkers = null;
	 
	 public File getFilePath(){
		 return sd;
	 }
	 
	 public void setFilePath(File sd){
          this.sd = sd;		 
	 }

	 public pictureData[] getPictureData(){
		 return picturemarkers;
	 }
	  
	 public void setPictureData(pictureData [] picData){
		 picturemarkers = picData;
	 }
	 
	 public void setRefresh(boolean refresh){
		 this.refresh = refresh;
	 }
	 
	 public boolean getRefresh(){
		 return refresh;
	 }
			 
}

ExampleActivity Class:

public class ExampleActivity extends Activity {

        GlobalState gs;

	public void onCreate(Bundle savedInstanceState) {
              gs = (GlobalState) getApplication();
        }

        public void examples(){  
            File temp = gs.getFilePath();
            if(gs.refresh()){
                gs.setRefresh(false);
             }
        }
} 

Manifest

-I do not fully understand why but it is needed for it to work.  Set the ‘name’ of your application to the path where the file is located.

<application
        android:name="your.package.name.GlobalState"