Thread: Exercise 165

Hi, so I have a question about this code. It says that if myID is equal to "t.getID" then return 0. Otherwise, it uses the "compareTo" method, within the definition of a compareTo method. How can a method be in the definition of itself?

public class TestClass implements Comparable<TestClass> 
{ 
  private String myName; 
  private int myID; 
 
  public TestClass( String name, int id ) 
  { 
    myName = name; 
    myID = id; 
  } 
 
  public String getName() 
  { 
    return myName; 
  } 
 
  public int getID() 
  { 
    return myID; 
  } 
 
//This section is where the editable code is. But I didn't write it. It was there to start me off I guess.:
 
public int compareTo( TestClass t )
{
  if ( myID == t.getID() )
    return 0;
 
  return myName.compareTo( t.getName() );
} 
 
//That was the first part of editable code
//That was the part that was mysterious to me.
 
} 
 
public class MainClass 
{ 
  public static void main( String[] args ) 
  { 
    TestClass c1 = new TestClass( "zulima", 1 ); 
    TestClass c2 = new TestClass( "fred", 2 ); 
    TestClass c3 = new TestClass( "eric", 3 ); 
    TestClass c4 = new TestClass( "jane", 2 ); 
    TestClass c5 = new TestClass( "hermione", 1 ); 
 
//I can also edit this line right here:
 
fSystem.out.println( c1.compareTo( c2 ) );
 
  } 
}

I'm also looking for a good explanation of what the "compareTo" method is trying to do, other than return 0. I mean, I know its supposed to compare but, how does it compare conceptually.

Thanks for the help. Sincerely, ghostheadx

How can a method be in the definition of itself?

The TestClass.compareTo() and String.compareTo() methods are not the same.

You can define what the compareTo() method does based on what you decide <, == (equals()), and > mean for two TestClass objects. You can count dirtySocks, tiresOnAxels, compare bodyTemps whatever you'd like.

So one compareTo() method can be used in the definition of the other. How is the inner method defined then? I mean originally.

--- Update ---

I don't completely understand the exercise. What am I supposed to do? I don't get the instructions.

How is the inner method defined then?

This is a lazy question. Refer to the String API.

I don't get the instructions.

What don't you understand? You might try searching for 'java compareto' to find other examples or tutorials to help you understand. If you've made the effort but can't find total consciousness, come back with specific questions with more clarity than, "I don't get it."