[android] android: how to use getApplication and getApplicationContext from non activity / service class

I'm using extending application class on Android to share my data across the entire app.

I can use getApplication() method from all my activities.

However, there are certain custom helper classes I created; for example, an XMLHelper class which does not inherit from any activity / service class.

Here the getApplication() method is not available.

How do I sort this out and what are the best design practices to solve this?

The getApplication() method is located in the Activity class, so whenever you want getApplication() in a non activity class you have to pass an Activity instance to the constructor of that non activity class.

assume that test is my non activity class:

Test test = new Test(this);

In that class i have created one constructor:

 public Class Test
 {
    public Activity activity;
    public Test (Activity act)
    {
         this.activity = act;
         // Now here you can get getApplication()
    }
 }

In order to avoid to pass this argument i use class derived from Application

public class MyApplication extends Application {

private static Context sContext;

@Override
public void onCreate() {
    super.onCreate();
    sContext=   getApplicationContext();

}

public static Context getContext() {
    return sContext;
}

and invoke MyApplication.getContext() in Helper classes.

Don't forget to update the manifest.

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example"> 
      <application 
       android:name=".MyApplication"
       android:allowBackup="true" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name"> 
         <activity....>
            ......
         </activity>
     </application> 
</manifest>

Casting a Context object to an Activity object compiles fine.

Try this:

((Activity) mContext).getApplication(...)

Either pass in a Context (so you can access resources), or make the helper methods static.

try this, calling the activity in the constructor

public class WebService {
private Activity activity;

        public WebService(Activity _activity){
            activity=_activity;
            helper=new Helper(activity);

        }
}

Sending your activity context to other classes could cause memoryleaks because holding that context alive is the reason that the GC can't dispose the object