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Android

Posted by dlpuxdzztg
dlpuxdzztg
8,243 Points

Unknown Class When Assigning Member Fields to Views

Hello.

I seem to be having trouble when I simply try to assign a member variable to a view. It tells me that my member variable is an "unknown class" when I assign it to a view. Could someone explain why it is giving me that error?

public class MainActivity extends AppCompatActivity {

    private ImageView mAddItemImage;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mAddItemImage addItemImage = findViewById(R.id.addAssignmentImage);
    }

    private void askUserForAssignment() {
        NewItemDialogFragment dialog = new NewItemDialogFragment();
        dialog.show(getSupportFragmentManager(), "assignment_dialog");
    }
}

Thank you.

David Remington
David Remington
18,326 Points

You have already declared the member variable and its type above, if you want to initialize it and assign it to the view in your layout you would only need something like this:

mAddItemImage = findViewById(R.id.addAssignmentImage);

1 Answer

Seth Kroger
Seth Kroger
56,413 Points
Seth Kroger
Seth Kroger
56,413 Points

findViewById() returns a general View type. If you declare a view variable as a more specific kind of View, like ImageView, you should remember to explicitly downcast.

mAddItemImage = (ImageView) findViewById(R.id.addAssignmentImage);