比较器坏了，我找不到错误

Question

[Jon Doe][Zed Adams][John Adams]

[John Adams][Zed Adams][Jon Doe]

public class ComparatorContactByName implements Comparator<Contact> {
    @Override
    public int compare(Contact c1, Contact c2) {

        // if lastNames of compared objects are not the same, compare them
        if(!c1.getLastName().toLowerCase().equals(c1.getLastName().toLowerCase())){
            return c1.getLastName().compareTo(c2.getLastName());

        // if lastNames are the same, compare by firstName
        }else if(c1.getLastName().toLowerCase().equals(c1.getLastName().toLowerCase())){
            return c1.getFirstName().toLowerCase().compareTo(c2.getFirstName().toLowerCase());

            // other case like firstName and lastName are the same, compare by id
        }else{
            return c1.getContactId() - c2.getContactId();
        }
    }
}

public void getAllContactsSortedByName(){

    List<Contact> allContacts = ContactRepository.listAllContacts();

    Comparator comparatorContactByName = new ComparatorContactByName();

    Collections.sort(allContacts, comparatorContactByName);

    if (allContacts == null) {
        System.out.println("No contact found. ");
    } else {
        for (Contact contact : allContacts) {
            System.out.println(contact.toString());
        }
    }
}

Contact{contactId= 133, firstName= John, lastName= Adams, email= [e-mail], groups= [gym]}    
Contact{contactId= 126, firstName= Jon, lastName= Doe, email= [e-mail], groups= [work, gym]}    
Contact{contactId= 130, firstName= Zed, lastName= Adams, email= [e-mail], groups= [work]}

“Zed”应该是第二名，但他是最后一名。有什么想法可以修复这个逻辑吗？

Answer 1

这就是你所做的：

c1.getLastName().toLowerCase().equals(c1.getLastName().toLowerCase()

您正在将C1的姓氏与C1的姓氏进行比较

相反，请执行以下操作：

c1.getLastName().toLowerCase().equals(c2.getLastName().toLowerCase()