作为重载的方法比较Comparator接口? [英] As overload the method compare the Comparator interface?
问题描述
我正在开发一个小型应用程序，我有一个带有方法和相应属性(名称，薪水，日期..)的"Employee"类，另一个类是雇员列表，我使用一个数组列表来存储雇员和不同的方法，例如添加员工，删除员工.
现在，我正在尝试按字母顺序和雇用日期(从最低到最高)对员工进行排序.
但是我有一个小问题，我不能使用该方法进行两次以上的比较，我一直在研究，并且也不能比较该方法是否可以按名称和日期对员工进行排序. 谢谢.
public class Employee
{
private String name;
private GregorianCalendar dateHire;
public GregorianCalendar getDateHire() { return dateHire; }
public void setDateHire(GregorianCalendar dateHire) { this.dateHire = dateHire; }
public getName() { return name;}
public setName (String name) { this.name = name;}
}
//--------------------------------------------- ---------
public class listEmployee implements Comparator <Employee>
{
ArrayList<Employee> Employees = new ArrayList<>();
@Override
public int compare(Employee e1, Employee e2) {
if (e1.getName() != e2.getName()) {
return 1;
} else {
return -1;
}
}
// now , when I call this function in the parent class , if you sort the names , now when I try
//to sort dates , not let me use the method compare more than twice
public void sortAlphabetical() {
Collections.sort(trabajadores,Employee.StuNameComparator);
}
//I was looking online and found these options, but not as a call in the main class
public static Comparator <Employee > sortDate = new Comparator<Employee >()
{
@Override
public int compare (Employee s1, Employee s2)
{
GregorianCalendar empTemporal = s1.getDateHire();
GregorianCalendar emTemporal2 = s2.getDateHire();
return empTemporal.compareTo(emTemporal2);
}
};
public static Comparator <Employee> StuNameComparator = new Comparator<Employee >() {
@Override
public int compare(Employee s1, Employee s2) {
String EmployeName1 = s1.getName().toUpperCase();
String EmployeName2 = s2.getName().toUpperCase();
//ascending order
return EmployeName1.compareTo( EmployeName2);
//descending order
//return StudentName2.compareTo(StudentName1);
}};
}
您不能重载Comparator<Employee>接口的compare方法，因为该方法只有一个签名-int compare(Employee s1, Employee s2).
但是，您可以具有多个实现该接口的类，并且可以在希望对Employee列表进行排序时选择相关的Comparator<Employee>实现.
I am developing a small application , I have an "Employee" class with methods and corresponding attributes (name , salary , date .. ) and another class that is a list of employees , which I use an arraylist to store employees and different methods , such as adding employee , delete employee .
Now I 'm trying to sort employees by alphabetical order and date of hire (lowest to highest).
But I have a little problem, I can not use the method compare more than 2 times, I have been researching and not whether it could overload the method compare to sort employees by name and date . thanks.
public class Employee
{
private String name;
private GregorianCalendar dateHire;
public GregorianCalendar getDateHire() { return dateHire; }
public void setDateHire(GregorianCalendar dateHire) { this.dateHire = dateHire; }
public getName() { return name;}
public setName (String name) { this.name = name;}
}
//------------------------------------------------------
public class listEmployee implements Comparator <Employee>
{
ArrayList<Employee> Employees = new ArrayList<>();
@Override
public int compare(Employee e1, Employee e2) {
if (e1.getName() != e2.getName()) {
return 1;
} else {
return -1;
}
}
// now , when I call this function in the parent class , if you sort the names , now when I try
//to sort dates , not let me use the method compare more than twice
public void sortAlphabetical() {
Collections.sort(trabajadores,Employee.StuNameComparator);
}
//I was looking online and found these options, but not as a call in the main class
public static Comparator <Employee > sortDate = new Comparator<Employee >()
{
@Override
public int compare (Employee s1, Employee s2)
{
GregorianCalendar empTemporal = s1.getDateHire();
GregorianCalendar emTemporal2 = s2.getDateHire();
return empTemporal.compareTo(emTemporal2);
}
};
public static Comparator <Employee> StuNameComparator = new Comparator<Employee >() {
@Override
public int compare(Employee s1, Employee s2) {
String EmployeName1 = s1.getName().toUpperCase();
String EmployeName2 = s2.getName().toUpperCase();
//ascending order
return EmployeName1.compareTo( EmployeName2);
//descending order
//return StudentName2.compareTo(StudentName1);
}};
}
You can't overload the compare method of the Comparator<Employee> interface, since there is just one signature to that method - int compare(Employee s1, Employee s2).
However, you can have multiple classes that implement that interface, and you can choose the relevant Comparator<Employee> implementation whenever you wish to sort your Employee list.
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