字符串合并排序实现

Question

我一直在尝试在正在进行的程序中实现各种类型的排序.到目前为止,我已经设法对整数进行排序.为了使这个(合并)代码排序为String数组而不是int数组,必须进行哪些更改？时间复杂度会有所不同吗？如果是这样,无论好坏？

编辑1:尝试使用compareTo.有些事似乎不对.返回错误,例如无法从字符串转换为int,反之亦然.固定

编辑2:我在行中得到NullPointerException if(array [low] .compareTo(array [high])> = 0).建议随时欢迎.

这是错误:

null  null  null  null  null  
Exception in thread "main" java.lang.NullPointerException
    at Merge.mergeSort_srt(Merge.java:28)
    at Merge.Sort(Merge.java:15)
    at Sort.main(Sort.java:73)

import java.io.File;


public class Merge 
{
    public void Sort (LinkedList listIn, int size) throws Exception
    {
        String[] mergeArray = new String[size] ;
        String textContent = null ;
        File outputFile ;

         for(int i = 0; i < mergeArray.length; i++)
           System.out.print( mergeArray[i]+"  ");
           System.out.println();
           mergeSort_srt(mergeArray,0, mergeArray.length-1);
           System.out.print("Values after the sort:\n");
           for(int i = 0; i <mergeArray.length; i++)
           System.out.print(mergeArray[i]+"  ");
           System.out.println();
           System.out.println("PAUSE");
    }


     public static void mergeSort_srt(String array[],int lo, int n)
     {
           int low = lo;
           int high = n;
           if (array[low].compareToIgnoreCase(array[high]) >= 0)
           {
               return;
           }

           int middle = ((n+1)/ 2);
           mergeSort_srt(array, low, middle);
           mergeSort_srt(array, middle + 1, high);
           int end_low = middle;
           int start_high = middle + 1;
           while ((array[low].compareToIgnoreCase(array[end_low]) <= 0) && (array[start_high].compareToIgnoreCase(array[high]) <= 0))
           {
               if(array[low].compareToIgnoreCase(array[start_high]) < 0)
               {
                   low++;
               }
               else
               {
                   String Temp = array[start_high];
           for (int k = start_high- 1; k >= low; k--)
           {
               array[k+1] = array[k];
           }
           array[low] = Temp;
           low++;
           end_low++;
           start_high++;
           }
           }
     }

}

Answer 1

这取决于你想你的字符串进行排序的方法,但该方法compareTo的字符串将帮助你实现那种排序:

返回:如果参数字符串等于此字符串,则返回值0; 如果此字符串按字典顺序小于字符串参数,则小于0的值; 如果此字符串按字典顺序大于字符串参数,则值大于0.