Question

我想使用quicksort来排序我的对象。名为Person的对象包含两个字段（firstname和lastname） class Person { private firstName; private lastName; //+getter/setter }
它应按姓氏排序，如果姓氏相同，则按名字排序。所以如果我有人[＆＃34;米勒＆＃34;，＆＃34;汤姆＆＃34 ;; ＆＃34; Smith＆＃34;，＆＃34; Jerry＆＃34;，＆＃34; Miller＆＃34;，＆＃34; Alex＆＃34;] 输出必须是＆＃34;米勒＆＃34;，＆＃34;亚历克斯＆＃34 ;; ＆＃34; Miller＆＃34;，＆＃34; Tom＆＃34;，＆＃34; Smith＆＃34;，＆＃34; Jerry＆＃34;。按姓氏排序有效，但我不知道如何实现第二部分。

这里的代码片段：
public void quicksort (List<Person> records, int left, int right) { int index = partition(records, left, right); if (left < index - 1) { quicksort (records, left, index - 1); } if (index < right) { quicksort (records, index, right); } }

public int partition(List<Person> records, int left, int right) {
int i = left, j = right;
Person tmp;
Person pivot = records.get(left);

while (i <= j) {
    while (records.get(i).getLastName().compareTo(pivot.getLastName()) < 0) {
        i++;
    }
    while (records.get(j).getLastName().compareTo(pivot.getLastName()) > 0) {
        j--;
    }
    //TODO: here I need something like if last name same, compare first name
    if (i <= j) {
        // swap elements
        tmp = records.get(i);
        records.set(i, records.get(j));
        records.set(j, tmp);
        i++;
        j--;
    }
}

return i; }
有什么想法吗？

Answer 1

为您的compareTo课程定义Person方法。比较姓氏，如果匹配，则首先命名：

public int compareTo(Person to) {
  int cmp = this.lastName.compareTo(to.lastName);
  if (cmp == 0)
    cmp = this.firstName.compareTo(to.firstName);
  return cmp;
}

然后你得到了：

while (records.get(j).compareTo(pivot) > 0) {

java quicksort多个标准

1 个答案: