类 Abstract 类和接口方法优先级

类中的实现（包括抽象声明）优先于所有接口默认值。

• 抽象类方法优先于接口默认方法 。

public interface Swim {
    default void backStroke() {
        System.out.println("Swim.backStroke");
    }
}

public abstract class AbstractSwimmer implements Swim {
    public void backStroke() {
        System.out.println("AbstractSwimmer.backStroke");
    }
}

public class FooSwimmer extends AbstractSwimmer {
}

以下声明

new FooSwimmer().backStroke();

会生产

AbstractSwimmer.backStroke

• 类方法优先于接口默认方法

public interface Swim {
    default void backStroke() {
        System.out.println("Swim.backStroke");
    }
}

public abstract class AbstractSwimmer implements Swim {
}

public class FooSwimmer extends AbstractSwimmer {
    public void backStroke() {
        System.out.println("FooSwimmer.backStroke");
    }
}

以下声明

new FooSwimmer().backStroke();

会生产

FooSwimmer.backStroke