在使用LiveData
为了解决这个问题,我们可以使用MediatorLiveData。MediatorLiveData是LiveData的子类,它允许将多个LiveData合并到一个LiveData中,并将它们的更新转发到一个单独的观察者。使用MediatorLiveData时,我们可以将LiveData的改变操作和观察者的触发操作分开来。例如,我们可以单独处理LiveData的更新操作,然后再触发相应的观察者更新。
以下是使用MediatorLiveData解决LiveData
public class MyViewModel extends ViewModel {
private MutableLiveData mLiveData1 = new MutableLiveData<>();
private MutableLiveData mLiveData2 = new MutableLiveData<>();
private MediatorLiveData mMediatorLiveData = new MediatorLiveData<>();
public MyViewModel() {
mMediatorLiveData.addSource(mLiveData1, value -> updateMediatorLiveData());
mMediatorLiveData.addSource(mLiveData2, value -> updateMediatorLiveData());
}
public LiveData getMediatorLiveData() {
return mMediatorLiveData;
}
private void updateMediatorLiveData() {
Boolean value1 = mLiveData1.getValue();
Boolean value2 = mLiveData2.getValue();
// Perform any necessary calculations on the LiveData values
// before setting the value of the MediatorLiveData.
mMediatorLiveData.setValue(value1 && value2);
}
public void setLiveData1(Boolean value) {
mLiveData1.setValue(value);
}
public void setLiveData2(Boolean value) {
mLiveData2.setValue(value);
}
}
在这个示例中,我们使用