java - CompareTo() 字符串/合并排序

Question

我在打印数组的降序时遇到问题。数组顺序类似于(标题、工作室、年份)。 我的顺序正确，但无法打印升序，它只能打印降序。示例

Movie2 a = new Movie2("布偶占领曼哈顿","哥伦比亚三星", 2001);
Movie2 b = new Movie2(“花木兰特别版”,“迪士尼”, 2004);
Movie2 c = new Movie2("怪物史莱克2", "梦工厂",2004);

  public static void sortTitles(Movie2[] a, int low, int high)
    {
        if ( low == high )
            return;

        int mid = ( low + high ) / 2;

        mergeTitle( a, low, mid, high);
    }  

    public static void mergeTitle( Movie2[] a, int low, int mid, int high )
    {
        Movie2[] temp = new Movie2[ high - low + 1 ];

        int i = low, j = mid + 1, n = 0;


        while ( i <= mid || j <= high )
        {

            int result= a[ i ].getTitle().compareTo(a[ j ].getTitle());
            int result2= a[ j ].getTitle().compareTo(a[ i ].getTitle());
            if ( i > mid )
            {
                temp[ n ] = a[ j ];
                j++;
            }
            else if ( j > high )
            {
                temp[ n ] = a[ i ];
                i++;
            }
            else if ( result < result2 )
            {
                temp[ n ] = a[ i ];
                i++;
            }

            else
            {
                temp[ n ] = a[ j ];
                j++;
            }
            n++;
        }

        for ( int k = low ; k <= high ; k++ )
            a[ k ] = temp[ k - low ];

    } // end of merge    

Answer 1

当您想要降序排列时，就像您已经做的那样:

int result= a[ i ].getTitle().compareTo(a[ j ].getTitle());
int result2= a[ j ].getTitle().compareTo(a[ i ].getTitle());

升序与降序相反，因此只需将比较取反即可:

int result= a[ i ].getTitle().compareTo(a[ j ].getTitle()) * -1;
int result2= a[ j ].getTitle().compareTo(a[ i ].getTitle()) * -1;

要选择执行此操作，您可以传入一个 boolean 值:

int result= a[ i ].getTitle().compareTo(a[ j ].getTitle()) *
   (isAscending ? -1 : 1);
int result2= a[ j ].getTitle().compareTo(a[ i ].getTitle()) *
   (isAscending ? -1 : 1);

(你说你的降序排序效果很好，这个答案假设这是真的。我还没有验证它。)