Question

在Sorting Arrays Using Variables Within the Array找到原始修改后的问题基本上，我似乎无法找到一种基于eventCodeString类的Event对数组进行排序的方法。因为字符串是字母数字（例如A123，B321，C222），传统的比较器（我刚刚发现，感谢原帖中的人）不起作用。我遇到并尝试实施的解决方案越多，我就越困惑。请帮助我理解涉及字符串的数组对象比较的逻辑。

package Chapter9;
import Chapter9.Event;
import javax.swing.JOptionPane;
import java.util.*;
public class EventDemo
{

    public static void main(String[] args)
    {
        callMotto();
                int x, sortMethod;
                Event[] eventStuff = new Event[8];
                for(x = 0; x < 8; ++x)
                {
                    eventStuff[x] = new Event();
                    eventStuff[x].setEventCodeString();
                    eventStuff[x].setGuests();
                    eventStuff[x].setContactNumber();
                    eventStuff[x].setEventStr();
                }
                //Sorting method start
                do
                {
                    String sorting;

                    sorting = JOptionPane.showInputDialog("Please choose sorting method:\n"
                            + "1 to sort by event number\n"
                            + "2 to sort by number of guests\n"
                            + "3 to sort by event type\n"
                            + "Type 99 to exit sorting list");
                    sortMethod = Integer.parseInt(sorting);
                    //Event code sorting start
                    if(sortMethod == 1)
                    {   
                        for(x = 0; x < 8; ++x)
                        {

                        } 
                    }
                    //Event code sorting end
                    if(sortMethod == 2)
                    {
                        for(x = 0; x < 8; ++x)
                        {
                            Arrays.sort(eventStuff, new Comparator<Event>() 
                            {
                                @Override
                                public int compare(Event o1, Event o2) 
                                {
                                    if (o1.getGuests() < o2.getGuests())
                                        return -1;
                                    else if (o1.getGuests() == o2.getGuests())
                                        return 0;
                                    else
                                        return 1;
                                }                                   
                            });
                            eventStuff[x].largeParty();
                        }
                    }
                    //Event type sorting start
                    if(sortMethod == 3)
                    {
                        for(x = 0; x < 8; ++x)
                        {
                            Arrays.sort(eventStuff, new Comparator<Event>() 
                            {
                                @Override
                                public int compare(Event o1, Event o2) 
                                {
                                    if (o1.getEventStr() < o2.getEventStr())
                                        return -1;
                                    else if (o1.getEventStr() == o2.getEventStr())
                                        return 0;
                                    else
                                        return 1;
                                }                                   
                            });
                            eventStuff[x].largeParty();
                        }
                    //Event type sorting end
                //Sorting method end
                    }
                    if(sortMethod == 99)
                        System.exit(0);
                }
                while(sortMethod != 99);
        }   
    public static void callMotto()
    {

        JOptionPane.showMessageDialog(null, "*******************************************************\n"
                        +   "* Carly's Makes The Food That Makes The Party! *\n"
                        +   "*******************************************************");

    }

}

Answer 1

仅仅因为您无法使用String来比较==，您应该使用String#equals代替<。 <=，!=，>，>=和Arrays.sort(eventStuff, new Comparator<Event>() { @Override public int compare(Event o1, Event o2) { if (o1.getEventStr() < o2.getEventStr()) return -1; else if (o1.getEventStr() == o2.getEventStr()) // this line return 0; else return 1; } });也是如此。您可以参考this other StackOverflow question进行解释。

也就是说，你必须替换：

Arrays.sort(eventStuff, new Comparator<Event>() {
    @Override
    public int compare(final Event o1, final Event o2) {
        return o1.getEventStr().compareTo(o2.getEventStr));
    }                                   
});

由：

String#compareTo(String)

String方法来自Java Comparable<String>实现Comparator的事实，这基本上意味着它们本身就知道如何比较它们。

由于我对此有所建议，我建议您也更改访客号码if (o1.getGuests() < o2.getGuests()) return -1; else if (o1.getGuests() == o2.getGuests()) return 0; else return 1;的实施情况：

return o1.getGuests() - o2.getGuests;

可能会成为：

o1.getGuests() < o2.getGuests()

如果你考虑一下，它确实会：

在o1.getGuests() == o2.getGuests()

负值

在o1.getGuests() > o2.getGuests()

0

在{{1}}

正值

......这正是我们所需要的：）

比较对象数组中的字母数字字符串

1 个答案: