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Base fragment to ensure the parent activity implements a contract interface.
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| /* Base fragment to ensure the parent activity implements a contract interface. */ | |
| public abstract class ContractFragment<T> extends Fragment { | |
| private T mContract; | |
| @Override | |
| public void onAttach(Activity activity) { | |
| if (!((Class)((ParameterizedType)getClass().getGenericSuperclass()).getActualTypeArguments()[0]).isAssignableFrom(activity.getClass())) | |
| throw new IllegalStateException(activity.getClass().getSimpleName() | |
| + " does not implement " + getClass().getSimpleName() + "'s contract interface."); | |
| //noinspection unchecked | |
| contract = (T)activity; | |
| super.onAttach(activity); | |
| } | |
| @Override | |
| public void onDetach() { | |
| super.onDetach(); | |
| mContract = null; | |
| } | |
| public final T getContract() { | |
| return mContract; | |
| } | |
| } | |
| /* Example fragment showing usage of ContractFragment. */ | |
| public class MyCoolFragment extends ContractFragment<MyCoolFragment.Contract> { | |
| public interface Contract { | |
| void sayHi(String message); | |
| } | |
| public void somethingHappened() { | |
| getContract().sayHi("Hi, Mom!"); | |
| } | |
| } |
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