java - 如何使用已经存在的构造函数？

Question

我正在使用 Firebase 为 child 构建一个简单的应用程序，但我经常收到此错误:

Android Firebase Database exception: not define a no-argument constructor

我有一个 Activity 类和另外两个辅助类 HomeActivities 和 OutsideActivities。这是我的类(class)代码:

public class Activities {
    private String type;
    private int count;

    public Activities() { }

    public Activities(String type, int count) {
        this.type = type;
        this.count = count;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    class HomeActivities {
        private String name;
        private int noOfChildren;

        HomeActivities() { }

        public HomeActivities(String name, int noOfChildren) {
            this.name = name;
            this.noOfChildren = noOfChildren;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getNoOfChildren() {
            return noOfChildren;
        }

        public void setNoOfChildren(int noOfChildren) {
            this.noOfChildren = noOfChildren;
        }
    }

    class OutsideActivities {
        private String name;
        private int noOfChildren;

        public OutsideActivities() { }

        public OutsideActivities(String name, int noOfChildren) {
            this.name = name;
            this.noOfChildren = noOfChildren;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getNoOfChildren() {
            return noOfChildren;
        }

        public void setNoOfChildren(int noOfChildren) {
            this.noOfChildren = noOfChildren;
        }
    }
}

请查看所有构造函数。即使我已经在每个类中定义了正确的构造函数，我也会收到此错误。如何解决这个问题？请帮助我。

Answer 1

有两种方法可以消除此错误。

1. 将两个内部类设为static。

2. 使两个内部类独立(每个类在它自己的单独文件中)。

就是这样!