java - 泛型扩展而不扩展 - 怎么做

Question

我做了一些事情:

class Tuple1<T1, T2> {
    private T1 a;
    private T2 b;

    public Tuple1(T1 a, T2 b) {
        this.a = a;
        this.b = b;
    }

    public T1 getA() {
        return a;
    }

    public T2 getB() {
        return b;
    }

    @Override
    public String toString() {
        return "[" + a.toString() + ", " + b.toString() + "]";
    }
}

现在我必须做 Tuple2(a、b + c 字段)和 Tuple3(a、b、c + d 字段)，它们将具有与 Tuple1 相同的功能，但没有 extends 和没有代码冗余。

Answer 1

你可以创建多个构造函数来做你想做的事:

例如:

private T1 a;
private T2 b;
//create a new attribute
private T2 c;

//constructor with two attributes
public Tuple1(T1 a, T2 b) {
    this.a = a;
    this.b = b;
}

//constructor with three attributes
public Tuple1(T1 a, T2 b, T2 c) {
    this.a = a;
    this.b = b;
    this.c = c;
}

//getters and setters of your attributes

所以当你想使用两个属性时:

Tuple1 t1 = new Tuple1(a, b);

所以当你想使用三个属性时:

Tuple1 t2 = new Tuple1(a, b, c);

您可以在此 Oracle 教程中了解更多信息:Getting Started

关于constructors和 here

希望对您有所帮助。