How we can pass data?

Question

How we can pass data of a methods MainAntivity to another class type SQLiteOpenHelper. For example we have :(MainActivity.java)

public class MainActivity extends ActionBarActivity {
public static String PACKAGE_NAME;
public String xxx(){
    PACKAGE_NAME = getApplicationContext().getPackageName();
    return PACKAGE_NAME;
    }
}

And another class is :(DB.java)

public class DB extends SQLiteOpenHelper{
  MainActivity cc = new MainActivity();
  Log.d("test",(String) cc.xxx());
}

But above code not work.

Answer 1

You shouldn't instantiate activity classes this way. Use a separate class instead, where you can define methods which you'd like to use somewhere else. In your case, receiving package name, I'd do something like this

public class PackageNameHelper
{
    private Context mContext;

    public PackageNameHelper(Context context)
    {
        mContext = context;
    }

    public String GetPackageName(){
        return mContext.getPackageName();
    }

}

Then in your activity / SQLite helper you'd do:

PackageNameHelper helper = new PackageNameHelper(getApplicationContext());
String packageName = helper.getPackageName()

Or you can make the helper class static, that way Context must be passed directly int the getPackageName() method, like

public class PackageNameHelper
{

    public static String GetPackageName(Context context){
        return context.getPackageName();
    }

}

and use it like

//Where context is an instance of a context
String packageName = PackageNameHelper.getPackageName(context);