Please help me with these java puzzle ?

Question

Dear all,
My friend send me typical java puzzle about java.util.ArrayList
which is getting messy. Please help me out. It's not a homework.

import java.util.*;
public class MyInt ______ ________ {
public static void main(String[] args) {
ArrayList list = new ArrayList();
list.add(new MyInt(2));
list.add(new MyInt(1));
Collections.sort(list);
System.out.println(list);
}
private int i;
public MyInt(int i) { this.i = i; }
public String toString() { return Integer.toString(i); }
________ int ___________ {
MyInt i2 = (MyInt)o;
return ________;
}
}

Hints , fill the underlines with below :
implements
extends
Sortable
Object
Comparable
protected
public
i = i2.i
i
i2.i=i
compare(MyInt o, MyInt i2)
compare(Object o, Object i2)
sort(Object o) sort(MyInt o)
compareTo(MyInt o)
compareTo(Object o)

import java.util.*;
public class MyInt implements Comparable {
public static void main(String[] args) {
ArrayList list = new ArrayList();
list.add(new MyInt(2));
list.add(new MyInt(1));
Collections.sort(list);
System.out.println(list);
}
private int i;
public MyInt(int i) { this.i = i; }
public String toString() { return Integer.toString(i); }
public int compareTo(Object o){
MyInt i2 = (MyInt)o;
return i;
}
}


output :
E:\>javac MyInt.java
Note: MyInt.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

E:\>java MyInt
[1, 2]

Answer 1

i never was good in java when i learnt it. just here to know the answers though.

Answer 2

my guess is the first one is implements Comparable

second: public int compareTo(Object o)

third: return i2.i - i;

none of the stuff matches for the third line - check interface Comprable in javadocs - there is no comparison you've been given, and even if it says == instead of = (which is a big difference) - it does not match what compareTo should return.

and yes, this is a homework