具有两个参数的通用 class

Question

这是问题：

Create a generic class named Duo that has two parameters, A and B. Declare a variable named first of type A, and the second variable named second of type B. Create a constructor that accepts these two parameters. In the constructor, assign these parameters respectively to the declared variables.

这是我能想到的解决方案：

public class Duo<T> {

    T first;
    T second;

    public Duo(T one , T two) {
        this.first = one;
        this.second = two;
    }

}

然后，当我进行下一个问题时，我卡住了。这是问题：

Use the Duo class in Question 4 to declare and create two objects as follows :

a) First object called sideShape consist of respectively String type and Integer type.

b) Second object called points consists of two Double types.

我很困惑。如何用两个参数调用泛型 class？

这是我的方法：

Duo <Object> sideShape = new Duo();

我说的对吗？

如果不行还请大家指出错误。我真的迷路了

Answer 1

您需要两种类型的仿制药：

public class Duo<P,Q> {

P first;
Q second;

public Duo(P one , Q two) {
    this.first = one;
    this.second = two;
}
}

以后可以使用如下：

Duo<String, Integer> duo = new Duo<>("Hello", 5);

具有两个参数的通用 class

Generic class with two parameters

java

generics