Mate pravdu, v textu ma byt compare() nikoli compareTo(), omlouvam se za zmateni.
Pri pouziti Arrays.sort() NEMUSI byt equals() prekryta, a to ani pri pouziti komparatoru ani v pripade, ze trida, jejiz instance se radi, implementuje rozhrani Comparable a tedy i metodu compareTo().
Konkretne zde je implementace Arrays.sort() zavolana v pripade, ze se teto metode preda krome pole i komparator. Zadne equals() se zde nevola, pouze compare():
private static void mergeSort(Object[] src,
Object[] dest,
int low, int high, int off,
Comparator c) {
int length = high - low;
// Insertion sort on smallest arrays
if (length < INSERTIONSORT_THRESHOLD) {
for (int i=low; i<high; i++)
for (int j=i; j>low && c.compare(dest[j-1], dest[j])>0; j--)
swap(dest, j, j-1);
return;
}
// Recursively sort halves of dest into src
int destLow = low;
int destHigh = high;
low += off;
high += off;
int mid = (low + high) >>> 1;
mergeSort(dest, src, low, mid, -off, c);
mergeSort(dest, src, mid, high, -off, c);
// If list is already sorted, just copy from src to dest. This is an
// optimization that results in faster sorts for nearly ordered lists.
if (c.compare(src[mid-1], src[mid]) <= 0) {
System.arraycopy(src, low, dest, destLow, length);
return;
}
// Merge sorted halves (now in src) into dest
for(int i = destLow, p = low, q = mid; i < destHigh; i++) {
if (q >= high || p < mid && c.compare(src[p], src[q]) <= 0)
dest[i] = src[p++];
else
dest[i] = src[q++];
}
}
