java - Trying to sort a map where the value is an object and I can sort by multiple values in the object -

java - Trying to sort a map where the value is an object and I can sort by multiple values in the object -

i'm trying sort map based on different possible values in pupil object. doesn't seem working me , can't seem figure out why. help appreciated. thanks!

protected static map<integer, student> sort(map<integer, student> unsortermap, string field) { comparator<integer> valuecomparator = new comparator<integer>() { public int compare(integer k1, integer k2) { int compare; if(field.equalsignorecase("name")) { compare = unsortermap.get(k1).getname().compareto(unsortermap.get(k2).getname()); } else { compare = integer.compare(unsortermap.get(k1).getindex(), unsortermap.get(k2).getindex()); } if (compare == 0) homecoming 1; else homecoming compare; } }; map<integer, student> sortedmap = new treemap <integer, student>(valuecomparator); sortedmap.putall(unsortermap); homecoming sortedmap; }

your comparator violates comparator contract. javadoc:

the implementor must ensure sgn(compare(x, y)) == -sgn(compare(y, x)) x , y

but in code, have

if (compare == 0) homecoming 1; else homecoming compare;

if 2 students have same value field utilize comparison, both compare(x,y) , compare(y,x) homecoming 1.

java sorting dictionary