我被分配了这个任务:
Complete the function void sort(List l) that sorts a list l that contains the strings "one","two","three","four" (although not necessarily in that order). You should declare a Comparator, and use this with the Collections.sort function. The comparator should use the comp function described above. The list l will be altered when it is sorted.
我已经编写的代码是这样的:
import java.util.*;
public class CW3 {
private static HashMap < String, Integer > map = new HashMap < String, Integer > ();
public CW3() {
map.put("one", 1);
map.put("two", 2);
map.put("three", 3);
map.put("four", 4);
List listB = Arrays.asList("A", "B", "C");
}
public static void main(String[] args) {
System.out.println(new CW3().comp("one", "two"));
System.out.println(new CW3().comp("two", "one"));
System.out.println(new CW3().comp("one", "one"));
}
int comp(String s1, String s2) {
int i1 = map.get(s1);
int i2 = map.get(s2);
return (i1 < i2 ? -1 : (i1 == i2 ? 0 : 1));
}
void sort(List l) {
Comparator c = new Comparator() {
public int compare(Object o1, Object o2) {
return 0; // FIXME change this so it calls comp
}
};
// now sort l using the comparator c
// FIXME complete this line
}
有什么想法从哪里开始吗?它说列表,所以我必须创建一个列表,但是我该如何对它们进行排序?
最佳答案
您需要做的是定义 compare
方法。它应该需要两个对象 o1
和o2
作为参数并返回
-
-1
当o1 < o2
-
0
当o1 == o2
-
1
当o1 > o2
您的Comparator
使用此方法作为决定元素顺序的基础。然后对列表进行排序 l
通过调用 Collections.sort(l, c)
,其中c
是Comparator
你已经定义了。
关于java - 对字符串列表进行排序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22332489/