java - 基于对象的两个值进行比较

Question

我正在开发一个“特许经营”程序，该程序具有所有者、状态和销售额，这些都在构造函数中设置并且无法更改。当我尝试编写compareTo方法时，我的问题就出现了。

package prob2;

public class Franchise implements Comparable <Franchise>  {
    final String owner;
    final String state;
    final double sales;

protected Franchise(String owner, String state, double sales ) {
    this.owner = owner;
    this.state = state;
    this.sales = sales;
}

public String toString() {
    String str = state + ", " + sales + ", " + owner;
    return str;
}

public String getState() {
    return state;
}

public double getSales() {
    return sales;
}
public int compareTo(Franchise that) {
    double thatSales = that.getSales();
    if (this.getState().compareTo(that.getState()) <0) 
        return -1;
    else if (this.getSales() > thatSales)
        return -1;
    else if (this.getSales() < thatSales)
        return 1;
    else
        return 0;
}

程序应实现可比较的接口(interface)，并应根据状态升序和销售额降序比较特许经营对象。我的问题是如何使用这两个值进行比较，有没有办法在一次比较中进行比较，或者我是否需要多个比较器？

示例:

州 = CA，销售额 = 3300 与州 = NC，销售额 = 9900 相比将返回负值

州 = CA，销售额 = 3300 与州 = CA，销售额 = 1000 相比将返回负值

州 = CA，销售额 = 3300 与州 = CA，销售额 = 9900 相比将返回正值

感谢您的所有帮助。

Answer 1

is there a way to do it in a single compare, or do i need multiple compareators?

就您而言，您不需要多个比较器。只需在单个 compareTo 方法中编写基于这两个属性的逻辑，如下所示:

public int compareTo(Franchise that) {
    if (this.getState().equals(that.getState()) {
        // Compare on the basis of sales (Take care of order - it's descending here)
    } else {
        // Compare on the basis of states.
    }
}