How to sort ArrayList Java

Question

I have this arrayList that i need to first sort from greatest to least by both item price and then after i need to sort it by the amount of items sold. Whats the easiest way to accomplish this? thanks!

 import java.util.*;
 public class salesPerson {
 //salesPerson fields
 private int salespersonID;
 private String salespersonName;
 private String productType;
 private int unitsSold = 0;
 private double unitPrice;
 //Constructor method
 public salesPerson(int salespersonID, String salespersonName, String productType, int unitsSold, double unitPrice)
 {
 this.salespersonID = salespersonID;
 this.salespersonName = salespersonName;
 this.productType = productType;
 this.unitsSold = unitsSold;
 this.unitPrice = unitPrice;
 }
 //Accessor for salesPerson
 public int getSalesPersonID()
 {
 return salespersonID;
 }
 public String getSalesPersonName()
 {
 return salespersonName;
 }
 public String getProductType()
 {
 return productType;
 }
 public int getUnitsSold()
 {
 return unitsSold;
 }
 public double getUnitPrice()
 {
 return unitPrice;
 }
 public double getTotalSold()
 {
 return unitsSold * unitPrice;
 }
 //Mutoators for salesPerson
 public void setSalesPersonID(int salespersonID)
 {
 this.salespersonID = salespersonID;
 }
 public void setSalesPersonName(String salespersonName)
 {
 this.salespersonName = salespersonName;
 }
 public void setProductType(String productType)
 {
 this.productType = productType;
 }
 public void setUnitsSold(int unitsSold)
 {
 this.unitsSold += unitsSold;
 }
 public void setUnitProce(double unitPrice)
 {
 this.unitPrice = unitPrice;
 }
 public static void main(String[] args)
 {
 ArrayList<salesPerson> salesPeople = new ArrayList<salesPerson>();
 Scanner userInput = new Scanner(System.in);
 boolean newRecord = true;
 boolean showReport = true;
 do
 {
 int salespersonID;
 String salespersonName;
 String productType;
 int unitsSold = 0;
 double unitPrice;
 System.out.println("Please enter the Salesperson Inoformation.");
 System.out.print("Salesperson ID: ");
 salespersonID = userInput.nextInt();
 System.out.print("Salesperson Name: ");
 salespersonName = userInput.next();
 System.out.print("Product Type: ");
 productType = userInput.next();
 System.out.print("Units Sold: ");
 unitsSold = userInput.nextInt();
 System.out.print("Unit Price: ");
 unitPrice = userInput.nextDouble();
 if(salesPeople.size() == 0) 
 {
 salesPerson tmp = new salesPerson(salespersonID, salespersonName, productType, unitsSold, unitPrice);
 salesPeople.add(tmp);
 }
 else
 {
 for(int i=0; i < salesPeople.size(); i++) 
 {
 if(salesPeople.get(i).getSalesPersonID() == salespersonID)
 {
 salesPeople.get(i).setUnitsSold(unitsSold);
 break;
 }
 else
 {
 salesPerson tmp = new salesPerson(salespersonID, salespersonName, productType, unitsSold, unitPrice);
 salesPeople.add(tmp);
 break;
 }
 //System.out.println(salesPeople.get(i).getSalesPersonName());
 }
 }
 System.out.print("Would you like to enter more data?(y/n)");
 String askNew = userInput.next();
 newRecord = (askNew.toLowerCase().equals("y")) ? true : false;
 }
 while(newRecord == true);

Answer 1

Write a custom comparator:

public SalesPersonComparator implements Comparator<salesPerson> {
 public int compare(final salesPerson p1, final salesPerson p2) {
 // get the comparison of the unit prices (in descending order, so compare p2 to p1)
 int comp = new Double(p2.getUnitPrice()).compareTo(new Double(p1.getUnitPrice()));
 // if the same
 if(comp == 0) {
 // compare the units sold (in descending order, so compare p2 to p1)
 comp = new Integer(p2.getUnitsSold()).compareTo(new Integer(p1.getUnitsSold()));
 }
 return comp;
 }
}

Edit (thanks to @Levenal):

Then use Collections.sort() to sort your list.

• Levenal: Once you have the Comparator I believe it is Collections.sort(...) that you can use to order your list?
• Jason: @user3579060 You put the comparator in a new class file. You put the Collections.sort() call wherever it is that you want to sort your list of salesPerson objects.