title: Error Message: The method sort(List<T>) in the type Collections is not applicable for the arguments (ArrayList<Date>)
body: <p>Keep getting error message, but don't know why. Can't get code to sort the list using Collections.sort()</p>
  
  <p>Here is what I have. 3 java files.</p>
  
  <p>The Interface file.</p>
  
  <pre><code>public interface Comparable&lt;T&gt; {
     public int compareTo(T other);
  }
  </code></pre>
  
  <p>The Class file.</p>
  
  <pre><code>public class Date implements Comparable&lt;Date&gt;{
  
  private int year;
  private int month;
  private int day;
  
  public Date(int month, int day, int year){   
     this.month = month;
     this.day = day;
     this.year = year;
  }
  
  public int getYear(){
     return this.year;
  }
  
  public int getMonth(){
     return this.month;
  }
  
  public int getDay(){
     return this.day;
  }
  public String toString(){
     return month + "/" + day + "/" + year;
  }
  
  
  public int compareTo(Date other){
      if (this.year!=other.year){
          return this.year-other.year;
      } else if (this.month != other.month){
          return this.month-other.month;
      } else {
          return this.day-other.day;
      }
  }
  </code></pre>
  
  <p>}</p>
  
  <p>The Client class</p>
  
  <pre><code>import java.util.*;
  
  public class DateTest{
     public static void main(String[] args){
  
    ArrayList&lt;Date&gt; dates = new ArrayList&lt;Date&gt;();
    dates.add(new Date(4, 13, 1743)); //Jefferson
    dates.add(new Date(2, 22, 1732)); //Washington
    dates.add(new Date(3, 16, 1751)); //Madison
    dates.add(new Date(10, 30, 1735)); //Adams
    dates.add(new Date(4, 28, 1758)); //Monroe     
  
  
    System.out.println(dates);
    Collections.sort(dates);
    System.out.println("birthdays = "+dates);
  
  }
  
  
  
  
  }
  </code></pre>
  
  <p>The error message I get is "The method sort(List) in the type Collections is not applicable for the arguments   (ArrayList)"</p>