jdk1.7的collections.sort(List list)排序问题

1.7使用旧排序：

System.setProperty("java.util.Arrays.useLegacyMergeSort", "true"); 

1.7代码

public static void sort(Object[] a) {

        if (LegacyMergeSort.userRequested)

            legacyMergeSort(a);

        else

            ComparableTimSort.sort(a);

    }

    /** To be removed in a future release. */

    private static void legacyMergeSort(Object[] a) {

        Object[] aux = a.clone();

        mergeSort(aux, a, 0, a.length, 0);

    }

1.6

public static void sort(Object[] a) {

        Object[] aux = (Object[])a.clone();

        mergeSort(aux, a, 0, a.length, 0);

    }