sorting an array of objects

Question

I have a method that sorts an array of objects by first names which prints out fine. However when i want to print the original order of objects it still prints out the sorted version. What can i change to fix this?

Main method + other methods

String[] firstNames= {"Fred","John","Amir", "James","Bob","Jay","Amber"};
String[] lastNames = {"Bond","Kates","Memar", "White","Marley","Brown","Nogofski"};
String[] idNumbers = {"R111111","A222222","AB11111", "KR22121","V311133","L242434","P102432"};
String[] employeeNum = {"1111","2222","3333", "4444","5555","6666","7777"};

Employee[] list = new Employee[firstNames.length];
list = listOfEmployees(firstNames,lastNames,idNumbers); // create the list of employees in one array    
System.out.println("List of employees before sorting...\n");
printEmployeeList(list); //print the list of employees
sortWithFirstName(list);
printEmployeeList(list);


public static void printEmployeeList(Employee[] list){
    String employees = Arrays.toString(list).replace("[", "").replace("]", "").replace(",", "");
    System.out.println(employees);
    }

public static Employee[] sortWithFirstName(Employee[] list){
  System.out.println("Sorting the list with the first name");
  {
boolean swap;
//String temp; //change this too
do
{
    swap = false;
  for (int i = 0; i < (list.length - 1); i++)
{
    if (list[i].getFirstName().compareTo(list[i+1].getFirstName()) > 0) //if first number is greater then second then swap
    {
        //swap

        Employee temp = list[i];
        list[i] = list[i + 1];
        list[i + 1] = temp;
        swap = true;
    }
}

} while (swap == true);
printEmployeeList(list);
}
 return list;
}

Employee class

public static class Employee{
    private String firstName;
    private String lastName;
    private String idNumber;
    private String employeeNumber;
    private int employeeCount;

    /**
     * Constructor
     * @param firstName first name
     * @param lastName last name
     * @param idNumber id number 
     */
    public Employee(String firstName, String lastName, String idNumber){
        this.firstName = firstName;
        this.lastName = lastName;
        this.idNumber = idNumber;
        employeeCount = 0;
    }
    /**
     * Accessors here
     */

    public String getFirstName(){
        return firstName;
    }

    public String getLastName(){
        return lastName;
    }

    public String getIdNumber(){
        return idNumber;
    }

    public String getEmployeeNumber(){
        return employeeNumber;
    }

    // mutators here

    /**
     * @param firstName first name
     */
    public void setFirstName(String firstName){
        this.firstName = firstName;
    }

    /**
     * @param lastName last name
     */
    public void setLastName(String lastName){
        this.lastName = lastName;
    }

    /** 
     * @param idNumber id number
     */
    public void setIdNumber(String idNumber){
        this.idNumber = idNumber;
    }

    /**
     * @param employeeNumber employee number
     */
    public void setEmployeeNumber(String employeeNumber){
        this.employeeNumber = "";
    }
    @Override
    public String toString(){
        String result = "\nFirst name: " + getFirstName() + "\nLast name: " + getLastName()
                + "\nId number: " + getIdNumber() + "\nEmployee number: ";
        if(getEmployeeNumber() == null){
        return result + "No employee number has been assigned yet!\n";
    }
        return result + getEmployeeNumber() + "\n";
    }

}

Answer 1

我认为当您对原始数组进行排序时，您需要创建一个新的数组实例，而不是直接在其中进行操作，而是使用新实例，因此当您返回原始数组时，您会发现它就像创建一个排序之前一样从原始数组复制

Answer 2

Here you print the original order, then rearrange the list variable. If you print the list again, it will be rearranged because it is the same variable.

printEmployeeList(list); //print the list of employees
sortWithFirstName(list);
printEmployeeList(list);

You need to create a copy of the original list and rearrange that one instead (eg. listArranged), then if you want to print the original list you can access the first list variable.