sort使用比较器的字符串列表

Question

我有 -

import java.util.*;

public class TestCompare {

    List<String> list = Arrays.asList("10", "1", "20", "11", "21", "12");
    Comparator<String> cmp = new Comparator<String>() {
        public int compare(String o1, String o2) {
            return Integer.valueOf(o1).compareTo(Integer.valueOf(o2));
        }
    };
    Collections.sort(list, cmp);
}

在Collections.sort(list, cmp);有错误- Syntax error on token "(", delete this token.这个语法有什么问题？

Answer 1

您需要将代码包装在方法中,而不是直接在类块中.

Answer 2

你不能直接在一个类中使用代码,它应该是一个方法,如main:

public class TestCompare {
    public static void main() {
      List<String> list = Arrays.asList("10", "1", "20", "11", "21", "12");
      Comparator<String> cmp = new Comparator<String>() {
      public int compare(String o1, String o2) {
        return Integer.valueOf(o1).compareTo(Integer.valueOf(o2));
      }
      };
      Collections.sort(list, cmp);
    }
}