G.V. G.V. - 2 days ago 5
Android Question

How to pass context?

I want to pass the context of the main activity to another class in order to create a Toast.

My main activity calls a class that will delete a file.
The class that deletes files will call a toast if the file does not exist.

Here is my code:

public class MyActivity extends AppCompatActivity
{
public void onCreate(Bundle savedInstanceState)
{
// create a file

Button buttoncreate = (Button)findViewById(R.id.create_button);

Button buttondelete = (Button)findViewById(R.id.delete_button);
...

buttondelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {

new DeleteFile();
}
});
}

public class DeleteFile extends AsyncTask {

@Override
public Object doInBackground(Object[] params) {
File root = android.os.Environment.getExternalStorageDirectory();
File dir = new File(root.getAbsolutePath() + "/mydir");
if (!(dir.exists())) {
CharSequence text = "Files do not exist!";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(getApplicationContext(), text, duration);
toast.show();

} else {
File file;
file = new File(dir, "mydata.bmp");
file.delete();
}
return(1);
}

}

Answer

First thing, you need Static Variable to declare global variable in Application Class,
like this

class GlobalClass extends Application {

  public static Context context;

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

  }

second you need set this class in AndroidManifest.xml inside application tag
like this:

<application
    android:name=".GlobalClass"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@android:style/Theme.Black.NoTitleBar" >

then whereever you need to access this data, get Application object by:

 Toast toast = Toast.makeText(GlobalClass.context, text, duration);
    toast.show();
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