Question

我设法翻译鸡尾酒排序方法的伪代码，但是当我运行它时，我收到运行时错误显示：

java.lang.ArrayIndexOutOfBoundsException: 1
    at Sorting.cocktailSort(Sorting.java:119)
    at Sorting.plotCocktailSortTest(Sorting.java:213)
    at Sorting.main(Sorting.java:19)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

以下是此排序方法的代码：

public static int cocktailSort(String[] numbers) {
    String [] inputCocktail = new String [numbers.length];
    for(int a = 0; a < numbers.length-2; a++) { 
        inputCocktail[a] = numbers [a]; 
    }      
    int left = 0;
    int right = numbers.length;
    boolean swapped =true; 
    String temp = "";
    int counter = 0;
    while (left < right && swapped) {
        swapped =false;
        for  (int mid = 0; mid < numbers.length; mid++) {
            if ((inputCocktail[mid].compareTo(inputCocktail[mid+1]))>0)
            { temp = inputCocktail[mid];
                inputCocktail[mid] = inputCocktail[mid+1];
                inputCocktail[mid+1] = temp;
                swapped = true;
            }  
        }    
        right--;
        if (swapped){
            swapped = false;
            for(int mid = numbers.length-2; mid>0; mid--)
                if ((inputCocktail[mid].compareTo(inputCocktail[mid-1]))<0)
                { temp = inputCocktail[mid];
                    inputCocktail[mid]= inputCocktail[mid-1];
                    inputCocktail[mid-1] = temp;
                    swapped = true;
                }
        }    
    }      
    left++;
    counter++;
    return counter;
}

无论我查看我的代码多少次，我都无法找到错误。任何帮助，将不胜感激。感谢。

编辑：第一种比较字符串的方法：

public static int compare(String a, String b)
       { 
  int compared = 0;
    a = a.toLowerCase();
    b = b.toLowerCase();
    //program assumes strings are equal

    for (int i = 0; i<a.length() && i<a.length(); i++){
        //for() loop goes on until the largest string
         int c = a.charAt(i);
        int d = b.charAt(i);
        //convert char into int for comparison just in case
        if(c < d){
            compared = -1;
             break;
            //breaks at the first occurence of non equal characters
        }
        else if(c > d){
            compared = 1;
            break;
            //same as above
        }
    }

     return compared;
  }

编辑＃2：

  public static void plotCocktailSortTest(int N_MAX) {
    int[] cocktail_sort_results = new int[N_MAX];

// test sorting for arrays from size 1 to N_MAX
    // MAKE SURE THAT YOUR METHOD IS ACTUALLY SORTING THE TEST ARRAY!!!!!!
    for (int i = 1; i < N_MAX; i++) {
      String[] test_array = ArrayUtilities.getRandomNamesArray(i);
      cocktail_sort_results[i] = cocktailSort(test_array);
    }
    // create a plot window
    PlotWindow pw = new PlotWindow("Cocktail Sort!");
    // add a plot to the window using our results array
    pw.addPlot("CocktailSort", cocktail_sort_results);
  }

Answer 1

这看起来不对

for  (int mid = 0; mid < numbers.length; mid++) {
       if ((inputCocktail[mid].compareTo(inputCocktail[mid+1]))>0)

如前所述，您只使用inputCocktail

之前的元素填充numbers.length - 2

基于您新发布的代码

for (int i = 1; i < N_MAX; i++) {
      String[] test_array = ArrayUtilities.getRandomNamesArray(i);

我不知道ArrayUtilities是什么，但也许getRandomNamesArray(1)会返回一个大小为1的数组

在以后的代码中，您尝试访问基于size - 2和size + 1的数组，这显然会失败。

我的鸡尾酒排序代码出了什么问题？

1 个答案: