演员表LinkedList <type> 到LinkedList <superType> （java）

Question

I've got an Interface SenseFitSensor. Class HardwareSensor implements it (future implements could be eg DummySensor).

Now I've got a method which requires LinkedList<SenseFitSensor> .

public ExerciseLearner(LinkedList<SenseFitSensor> sensorList){

I cannot provvide it with a LinkedList<HardwareSensor> , because LinkedList cannot be cast to SensefitSensor .

What does work is

LinkedList<SenseFitSensor> senseFitSensors = new LinkedList<SenseFitSensor>(hardwareSensors);
    learner = new ExerciseLearner(senseFitSensors);

But a new linkedlist is created each time. Is there a better way?

Answer 1

You can use bounded wild cards

public ExerciseLearner(LinkedList<? extends SenseFitSensor> sensorList){

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References

• Upper Bounded Wildcards