What is Variance?
Variance describes how subtyping relationships transfer to generic types.
Covariance (Output Positions)
If Dog extends Animal, then Producer<Dog> extends Producer<Animal>
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LearnStep 1 of 2
Understanding Variance
Learning Objectives
- •Understand variance
- •Know covariant/contravariant positions
- •Apply variance rules
Lesson Outline
LearnStep 1/2
Understanding Variance
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Contravariance (Input Positions)
If Dog extends Animal, then Consumer<Animal> extends Consumer<Dog>
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Invariance
When T appears in both positions, no subtyping relationship:
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