compareto

like compareTo, that have to be "reflexive, antisymmetric and transitive", are there any rules to implement the compare method?? thanks PermGenError From Comparator API : The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.) The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0. Finally, the implementor must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn

I need to use the comparable interfact and a compareTo method to sort a list of students alphabetically and then by test score. I'm struggling at getting this to work in my application. The list of names needs to be read from a text file. I don't know how many names will be in the text file that my professor uses except that it will be less than 100. I am also supposed to display the average of the grades at the bottom as well as write a message next to any student that is 15 points below average. I have not really gotten to the writing message part as I am currently stuck on getting the names

I'm trying to generate a hashCode() method for my simple class but i'm not getting anywhere with it. I would appreciate any help. I've implemented the equals() method, which looks as follows, and would also like to know if I need to implement compareTo() method. I've imported java.lang.Character to use character.hashCode() but it doesn't seem to work. private class Coord{ private char row; private char col; public Coord(char x, char y){ row = x; col = y; } public Coord(){}; public char getX(){ return row; } public char getY(){ return col; } public boolean equals(Object copy){ if(copy == null){

I am trying to sort a list of type A named BinOrder in class B according to Class A's int r. However i am receiving this error for the line Collections.sort(BinOrder); The method sort(List<T>) in the type Collections is not applicable for the arguments (ArrayList<A>) Class A: public class A{ int s; int r; public A(int si, int ri) { s=si; r= ri; } } Class B: import java.util.ArrayList; import java.util.Collections; public class B implements Comparable<A> { public Iterator<A> randomMethodName(int a) { ArrayList<A> BinOrder = new ArrayList<A>(); A a = new A(1,3) A a2 = new A(1,4) BinOrder.add(a);

I'm having trouble writing a compareTo() and charAt() methods for a linked list object that builds strings. The class, called LString contains a constructor and a few other methods. It runs with another file that tests its ability as a linked list string builder, and I am receiving this error message: Running constructor, length, toString tests (10 tests) Starting tests: .......... Time: 0.000 OK! (10 tests passed.) Running compareTo and equals tests (18 tests) Starting tests: EEEEEEEE.EEE.E.... Time: 0.016 There were 12 failures: 1) t21aTestCompareTo[0](LStringTest$LStringCompareToTest) java