InterfaceComparableLab/src/main/java/com/zipcoder/payment/PaymentPresenter.java

package com.zipcoder.payment;

import java.util.Arrays;

public class PaymentPresenter {

    public PaymentPresenter() {
    }

    public String toString(Payment[] p){
        Arrays.sort(p);
        StringBuilder answer = new StringBuilder();

        for(Payment payment: p){
            answer.append(payment.getShortDescription()+"\n");
        }
        return answer.toString();
    }

    public String toStringByPayerName(Payment[] p) {
        PaymentSortByPayer nameSort = new PaymentSortByPayer();
        StringBuilder answer = new StringBuilder();
        Arrays.sort(p, nameSort);

        for(Payment payment: p){
            answer.append(payment.getShortDescription()+"\n");
        }
        return answer.toString();
    }

    public String toStringById(Payment[] p){
        Arrays.sort(p,
                (Payment a, Payment b) -> {  return Integer.signum((int)(a.getId() - b.getId())); }
        );
        StringBuilder answer = new StringBuilder();

        for(Payment payment: p){
            answer.append(payment.getShortDescription()+"\n");
        }
        return answer.toString();
    }
}