Done

pom.xml

@@ -7,6 +7,18 @@
     <groupId>com.zipcoder</groupId>
     <artifactId>payment</artifactId>
     <version>1.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>8</source>
+                    <target>8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
     <dependencies>
         <dependency>
             <groupId>org.junit.jupiter</groupId>

src/main/java/com/zipcoder/payment/Check.java

@@ -9,10 +9,10 @@ public class Check implements Payment {
         this.accountNumber=accountNumber;
 
     }
-    long id;
-    String payerName;
-    String routingNumber;
-    String accountNumber;
+    private long id;
+    private String payerName;
+    private String routingNumber;
+    private String accountNumber;
     public long getId()
     {
         return this.id;
@@ -49,12 +49,26 @@ public class Check implements Payment {
     {
         String number=getaccountNumber();
         StringBuilder br =new StringBuilder();
-        br.append("Check").append(" ").append(this.getPayerName()).append(" ").
-                append(" ").append("****").append(number.substring(number.length()-4));
+        br.append("Check").append(" ").append(this.getPayerName()).append(" ")
+                .append("***").append(number.substring(number.length()-4));
         System.out.println(br.toString());
         return br.toString();
     }
     public int compareTo(Payment o) {
-       return this.getShortDescription().compareTo(o.getShortDescription());
+        int number=0;
+
+       if(this.getShortDescription().compareTo(o.getShortDescription())==0)
+       {
+           number=0;
+       }
+        if(this.getShortDescription().compareTo(o.getShortDescription())<0)
+        {
+            number=-1;
+        }
+        if(this.getShortDescription().compareTo(o.getShortDescription())>0)
+        {
+            number=1;
+        }
+        return number;
     }
 }

src/main/java/com/zipcoder/payment/CreditCard.java

@@ -67,6 +67,20 @@ public class CreditCard implements Payment{
     }
 
     public int compareTo(Payment o) {
-        return this.getShortDescription().compareTo(o.getShortDescription());
+        int number=0;
+
+        if(this.getShortDescription().compareTo(o.getShortDescription())==0)
+        {
+            number=0;
+        }
+        if(this.getShortDescription().compareTo(o.getShortDescription())<0)
+        {
+            number=-1;
+        }
+        if(this.getShortDescription().compareTo(o.getShortDescription())>0)
+        {
+            number=1;
+        }
+        return number;
     }
 }

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

@@ -1,6 +1,43 @@
 package com.zipcoder.payment;
 
+import java.util.Arrays;
+
 public class PaymentPresenter {
+    PaymentSortByPayer sorter;
+    public String toString(Payment[] pay)
+    {
+        Arrays.sort(pay);
+        StringBuilder br=new StringBuilder();
+        for(Payment o:pay)//For each Payment object in pay array
+        {
+
+            br.append(o.getShortDescription()+"\n");
+        }
+        return br.toString();
+    }
+    public String toStringName(Payment[] pay)
+    {
+        Arrays.sort(pay,new PaymentSortByPayer());
+        StringBuilder br=new StringBuilder();
+        for(int i=0;i<pay.length;i++)
+        {
+
+            br.append(pay[i].getShortDescription()+"\n");
+        }
+        return br.toString();
+    }
+    public String toStringById(Payment[] pay)
+    {
+        Arrays.sort(pay, (Payment o1,Payment o2) -> Long.compare(o1.getId(),o2.getId()));
+        StringBuilder br;
+        br = new StringBuilder();
+        for(int i=0;i<pay.length;i++)
+        {
+            br.append(pay[i].getShortDescription()+"\n");
+        }
+        return br.toString();
+    }
+
 
 
 }

src/main/java/com/zipcoder/payment/PaymentSortByPayer.java

@@ -1,12 +1,14 @@
 package com.zipcoder.payment;
 
-public class PaymentSortByPayer implements Comparable<Payment> {
-    public int compareTo(Payment o) {
-        return 0;
-    }
-    public int compare(Payment o1,Payment o2)
+import java.util.Comparator;
 
+public class PaymentSortByPayer implements Comparator<Payment> {
+//string-comparable
+    //Comparator->can compare long,int(two objects)
+    public int compare(Payment o1,Payment o2)
     {
-     return o1.getPayerName().compareTo(o2.getPayerName());
+        return o1.getPayerName().compareTo(o2.getPayerName());
     }
+
+
 }

src/main/java/com/zipcoder/payment/Paypal.java

@@ -46,6 +46,20 @@ public class Paypal implements Payment {
     }
 
     public int compareTo(Payment o) {
-        return this.getShortDescription().compareTo(o.getShortDescription());
+        int number=0;
+
+        if(this.getShortDescription().compareTo(o.getShortDescription())==0)
+        {
+            number=0;
+        }
+        if(this.getShortDescription().compareTo(o.getShortDescription())<0)
+        {
+            number=-1;
+        }
+        if(this.getShortDescription().compareTo(o.getShortDescription())>0)
+        {
+            number=1;
+        }
+        return number;
     }
 }

src/test/java/com/zipcoder/payment/PaymentPresenterTest.java

@@ -1,4 +1,68 @@
 package com.zipcoder.payment;
 
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 public class PaymentPresenterTest {
+    @Test
+    public void testnoPayment()
+    {
+        Payment[] payments = new Payment[0];
+        PaymentPresenter presenter = new PaymentPresenter();
+        String expected = "";
+
+        String actual = presenter.toString(payments);
+
+        assertEquals(expected, actual);
+    }
+    @Test
+    public void multiplepayments()
+    {
+        Payment[] payments = new Payment[2];
+        Payment paypal = new Paypal(4, "Tia Mowry", "tia@mowry.com");
+        Payment check = new Check(81L, "Tia Mowry", "11432543", "134344551");
+
+        payments[0] = paypal;
+        payments[1] = check;
+
+        PaymentPresenter presenter = new PaymentPresenter();
+        String expected = "Check Tia Mowry ***4551\nPaypal Tia Mowry tia@mowry.com\n";
+
+        String actual = presenter.toString(payments);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void testtoStringByPayerName()
+    {
+        Payment[] payments = new Payment[2];
+        Payment paypal = new Paypal(4, "Tamara Mowry", "tamara@mowry.com");
+        Payment check = new Check(81L, "Tia Mowry", "11432543", "134344551");
+
+        payments[0] = paypal;
+        payments[1] = check;
+
+        PaymentPresenter presenter = new PaymentPresenter();
+        String expected = "Paypal Tamara Mowry tamara@mowry.com\nCheck Tia Mowry ***4551\n";
+
+        String actual = presenter.toStringName(payments);
+        assertEquals(expected, actual);
+    }
+    @Test
+    public void testtoStringById()
+    {
+        Payment[] payments = new Payment[2];
+        Payment paypal = new Paypal(120, "Tamara Mowry", "tamara@mowry.com");
+        Payment check = new Check(81L, "Tia Mowry", "11432543", "134344551");
+
+        payments[0] = paypal;
+        payments[1] = check;
+
+        PaymentPresenter presenter = new PaymentPresenter();
+        String expected = "Check Tia Mowry ***4551\nPaypal Tamara Mowry tamara@mowry.com\n";
+
+        String actual = presenter.toStringById(payments);
+        assertEquals(expected, actual);
+    }
 }