Question

我想在JUnit测试用例中创建一个对象KalkulatorI.AccumulatorI。当我创建Kalkulator.Accumulator时，它就可以了（Kalkulator.Accumulator t2 = new Kalkulator().new Accumulator()）。如何创建这样的接口对象？我试过了：

KalkulatorI.AccumulatorI t = new KalkulatorI.AccumulatorI();

或

KalkulatorI.AccumulatorI t = new KalkulatorI().new AccumulatorI();

但它不起作用。

AccumulatorI.java：

public interface AccumulatorI {
    public int getValue();
    public void setValue(int acc);
}

KalkulatorI.java：

public interface KalkulatorI {
    public void setAccumulatorA(AccumulatorI a);
    public void setAccumulatorB(AccumulatorI a);
}

Kalkulator.java：

public class Kalkulator implements KalkulatorI {

    private AccumulatorI AA;
    private AccumulatorI BB;

    class Accumulator implements AccumulatorI{
        private int acc;

        public int getValue(){
            int res = this.acc;
            return res;
        }

        public void setValue(int acc){
            this.acc=acc;
        }
    }

    public void setAccumulatorA(AccumulatorI a){
        this.AA=a;
    }
    public void setAccumulatorB(AccumulatorI a){
        this.BB=a;
    }
}

Answer 1

您无法实例化界面，因此无法调用new AccumulatorI()。请查看Oracle's documentation

嵌套类，实现了接口对象

1 个答案: