Still trying to understand compareTo() method

[saurabhthard aggarwal]

/*WHEN COMPARETO () METHOD IS CALLED FOR ADDING THE SECOND ELEMENT IN THE TREESET WHICH OBJECT VALUE IS COMPARED TO WHICH OBJECT VALUE.

  import java.util.*; 

class Comparable1 
{ 
public static void main(String[] args) 
{ 
TreeSet ts1=new TreeSet(); 

ts1.add(new Student("Saurabh","Thard",100,0.1)); 

ts1.add(new Student("Sachin","Tendulkar",200,0.01)); 

ts1.add(new Student("Prannoy","Roy",300,03.03)); 

ts1.add(new Student("Barkha","Dutt",400,04.4)); 

ts1.add(new Student("Vikram","Chandra",500,5.05)); 

Object [] studArray=ts1.toArray(); 

Student s; 

for(Object obj:studArray) 

{ 
s=(Student) obj; 

System.out.printf("NAME = %s %s STUDENT ID =%d GPA=%.1f \n",s.fname(),s.lname(), 
s.StudentID(),s.gpa()); 

} 
} 
} 
class Student implements Comparable 
{ 

String fname; 
String lname; 
int studentID; 
double gpa; 

public Student(String fname,String lname,int studentID,double gpa) 
{ 

if(fname==null || lname==null || studentID==0 || gpa==0.0) 

{ 
throw new IllegalArgumentException(); 
} 

this.fname=fname; 
this.lname=lname; 
this.studentID=studentID; 
this.gpa=gpa; 
} 

public String fname() 
{ 
return fname; 
} 

public String lname() 
{ 
return lname; 
} 

public int StudentID() 
{ 
return studentID; 
} 

public double gpa() 
{ 
return gpa; 
} 

public int compareTo(Object o) //OVER-RIDING COMPARETO SINCE IT IMPLEMENTS COMPARABLE. 
{ 
double f= gpa- ((Student)o).gpa; 

if(f==0.0) 
return 0; 

else if(f<0.0) 
return -1; 

else 
return 1; 
} 
} 
  

[Deepak Bala]

Thanks for using the CODE tags saurabh. However can you please edit the original post instead of creating a new one ? This will help you track your responses better and will avoid confusion due to double posting. Your original post is here

http://www.coderanch.com/t/436485/Programmer-Certification-SCJP/certification/Still-not-getting-working-compareTo

Thanks