在数组中调用对象方法。reduce(…)

我有以下3个文件,

A.java:

class A {

    private float b;    

    public A(float b) {
        this.b = b;
    }

    public float getB() {
        return b;
    }

}

C.java:

import java.util.Arrays;

class C {

    private A[] d;
    private int i = 0;

    public C() {
        d = new A[2];
    }

    public float totalB() {
        return Arrays.stream(d).reduce((e, f) -> e.getB() + f.getB()).get();
    }

    public void addB(A b) {
        d[i++] = b;
    }

}

class D {

    public static void main(String[] args) {
        C c = new C();
        c.addB(new A(3));
        c.addB(new A(5));
        System.out.println(c.totalB())
    }

}

我希望D.java中的最后一行输出8,但是我得到了以下错误:

error: incompatible types: bad return type in lambda expression return Arrays.stream(d).reduce((e, f) -> e.getB() + f.getB()).get(); ^ float cannot be converted to A