Question

Im a newbie coder and I was getting very frustrated because I keep getting compiler errors. This is a homework assignment and what I’m suppose to do is implement the Comparable class to compare any two String objects so it will return the maximum and minimum. I keep getting compiler errors and I dont exactly know why I do.

public class DataSet implements Comparable
{
   private Object maximum;
   private Object least;
   private int answer;

public int compareTo(Object other)
{
answer = this.getName().compareTo(other.getName());
return answer;

}

public Object getLeast(Object other)
 {
   if(answer<0)
   return this;
   else
   return other;
  }

 public Object getMaximum(Object other)
 {
   if(answer>0)
   return this;
   else
   return other;
 }


}

the error is the getName Method

public interface Comparable
{
    public int compareTo(Object anObject);
}


public class DataSetTester
{
public static void main(String[] args)
{
    DataSet ds = new DataSet();
    String s = "john";
    String a = "bob";
    ds.s.compareTo(a);
    System.out.println("Maximum Word: " + ds.getMaximum());
    System.out.println("Least Word: " + ds.getLeast());

 }
}


incompatible types
    String s = "john";

incompatible types
    String a = "bob";

error: cannot find symbol
    ds.s.compareTo(a);

 error: method getMaximum in class DataSet cannot be applied to given types;
    System.out.println("Maximum Word: " + ds.getMaximum());
error: method getLeast in class DataSet cannot be applied to given types;
    System.out.println("Least Word: " + ds.getLeast());

Answer 1

String already implements Comparable interface, so I’m not sure what exactly your task is.

answer = this.getName().compareTo(other.getName());

Object has no getName() method. If you implemented it in DataSet you need to change the type of other or add a cast:

answer = this.getName().compareTo(((DataSet)other).getName());

.

incompatible types
    String s = "john";

This is strange. Maybe you created your own String class? If so, you cannot assign java’s String to your String

error: cannot find symbol
    ds.s.compareTo(a);

DataSet has no field s. Expression ds.s is not valid.

error: method getMaximum in class DataSet cannot be applied to given types;
    System.out.println("Maximum Word: " + ds.getMaximum());

You need to add argument to getMaximum() e.g. getMaximum(null). Or, remove the argument from method declaration.