Question

我在编写一些我编写的代码时遇到了问题。该代码用于对目录数组进行排序，然后返回已排序的数组。传递给程序的数组如下所示：{"/","/usr/","/usr/local/","/usr/local/bin/","/games/","/games/snake/","/homework/","/temp/downloads/"}

对此的排序答案是：

{ "/", "/games/", "/homework/", "/usr/", "/games/snake/", 
     "/temp/downloads/", "/usr/local/", "/usr/local/bin/" }

所以基本上，首先放置最深的目录。如果两个目录具有相同的深度，我们将根据第一个单词按字母顺序排序。到目前为止我的代码是：

import java.util.Arrays;
import java.util.Comparator;

public class Dirsort {

  class APTComp implements Comparator<String> {

      public int compare(String a, String b) {
          String[] d1 = a.split("/");
          String[] d2 = b.split("/");
          int diff = d1.length - d2.length;

          if (diff != 0) {
            return diff;
          } //{"/","/usr/","/usr/local/","/usr/local/bin/","/games/","/games/snake/","/homework/","/temp/downloads/"}

          return a.compareTo(b);
        }



      public String[] sort(String[] dirs) {
        Arrays.sort(dirs);
        return dirs;
      }
}

你能告诉我你在这里发现的任何错误吗？我的Arrays.sort（）调用是否使用我的modifiend比较方法？

非常感谢， Junaid

Answer 1

默认情况下，Arrays.sort（）方法使用自然顺序进行排序。由于您的案例中的数组是String，因此默认情况下它将根据字符串的字母顺序进行排序。

要获得所需的结果，您必须将自定义比较器实现的实例传递给Arrays.sort（）。

将public String[] sort(String[] dirs)课程中的APTComp方法替换为：

public String[] sort(String[] dirs) 
{
    Arrays.sort(dirs, new APTComp());
    return dirs;
}

Answer 2

除非你打电话，否则Arrays.sort不会直接按你的比较器排序。你应该使用

Arrays.sort(dirs, new APTComp());

修订后的代码：

import java.util.Arrays;
import java.util.Comparator;

public class Main {

  class APTComp implements Comparator<String> {

      public int compare(String a, String b) {
          String[] d1 = a.split("/");
          String[] d2 = b.split("/");
          int diff = d1.length - d2.length;

          if (diff != 0) {
            return diff;
          } //{"/","/usr/","/usr/local/","/usr/local/bin/","/games/","/games/snake/","/homework/","/temp/downloads/"}

          return a.compareTo(b);
        }
  }


      public String[] sort(String[] dirs) {
        Arrays.sort(dirs, new APTComp());
        return dirs;
      }

      public static void main(String[] args) {
          Main main = new Main();
          String[] result = main.sort(new String[] {"/","/usr/","/usr/local/","/usr/local/bin/","/games/","/games/snake/","/homework/","/temp/downloads/"});
          for(int i=0; i<result.length; i++) {
            System.out.println(i + ": " + result[i]);
          }
      }
}

结果： 0：/ 1：/游戏/ 2：/作业/ 3：/ usr / 4：/ games / snake / 5：/ temp / downloads / 6：/ usr / local / 7：/ usr / local / bin /

请参阅another example

Answer 3

此代码正常运行，请检查

import java.util.Arrays;
import java.util.Comparator;

public class Dirsort {

class APTComp implements Comparator<String> {

    public int compare(String a, String b) {
        String[] d1 = a.split("/");
        String[] d2 = b.split("/");
        int diff = d1.length - d2.length;
        if (diff != 0) {
            return diff;
        }
        return a.compareTo(b);
    }

    public String[] sort(String[] dirs) {
        Arrays.sort(dirs);
        return dirs;
    }
}

public static void main (String[] args) {
  String[] arr = new String[] {"/","/usr/","/usr/local/","/usr/local/bin/","/games/","/games/snake/","/homework/","/temp/downloads/"};
Dirsort ds = new Dirsort();
  Arrays.sort(arr, ds.new APTComp());
  for (String s : arr) {
      System.out.println(s);
  }
}
}

输出：
/
/游戏/
/功课/
在/ usr /
/游戏/蛇/
/温度/下载/
在/ usr /本地/
/ usr / local / bin /

Java嵌入式比较器类

3 个答案: