# concrete_class_with_abstract_member

> Details about the concrete_class_with_abstract_member diagnostic produced by the Dart analyzer.



_'{0}' must have a method body because '{1}' isn't abstract._

## Description

The analyzer produces this diagnostic when a member of a concrete class is
found that doesn't have a concrete implementation. Concrete classes aren't
allowed to contain abstract members.

## Example

The following code produces this diagnostic because `m` is an abstract
method but `C` isn't an abstract class:

```dart
class C {
  [!void m();!]
}
```

## Common fixes

If it's valid to create instances of the class, provide an implementation
for the member:

```dart
class C {
  void m() {}
}
```

If it isn't valid to create instances of the class, mark the class as being
abstract:

```dart
abstract class C {
  void m();
}
```

