作为参考，我正在Java编程BlueJ。
我对这门语言比较陌生，我在排序方面遇到了麻烦。
我正在尝试调用/测试主类中的所有5种排序方法。
我想出了如何调用/测试Quicksort：
Sorting.quickSort(friends, 0, friends.length-1);
但其他人工作不正常。特别是这些：
Sorting.mergeSort(friends, 0, friends.length-1);
Sorting.PbubbleSort(friends, 0, friends.length-1);
Sorting.PinsertionSort(friends, 0, friends.length-1);
Sorting.selectionSort(friends, 0, friends.length-1);
希望有人可以帮助我。
作为参考，这是未排序时的输出：
Smith, John 610-555-7384
Barnes, Sarah 215-555-3827
Riley, Mark 733-555-2969
Getz, Laura 663-555-3984
Smith, Larry 464-555-3489
Phelps, Frank 322-555-2284
Grant, Marsha 243-555-2837
这是 排序后的输出：
Barnes, Sarah 215-555-3827
Getz, Laura 663-555-3984
Grant, Marsha 243-555-2837
Phelps, Frank 322-555-2284
Riley, Mark 733-555-2969
Smith, John 610-555-7384
Smith, Larry 464-555-3489
这是班级Sorting，我应该注意这是正确的：
public class Sorting{
/**
* Swaps to elements in an array. Used by various sorting algorithms.
*
* @param data the array in which the elements are swapped
* @param index1 the index of the first element to be swapped
* @param index2 the index of the second element to be swapped
*/
private static <T extends Comparable<? super T>> void swap(T[] data,
int index1, int index2){
T temp = data[index1];
data[index1] = data[index2];
data[index2] = temp;
}
/**
* Sorts the specified array of objects using the quick sort algorithm.
* @param data the array to be sorted
*/
public static <T extends Comparable<? super T>> void quickSort(T[] data){
quickSort(data, 0, data.length - 1);
}
/**
* Recursively sorts a range of objects in the specified array using the
* quick sort algorithm. The parameters min and max represent the range of
* values on which the sort is performed.
*
* @param data the array to be sorted
* @param min the minimum index in the range to be sorted
* @param max the maximum index in the range to be sorted
*/
public static <T extends Comparable<? super T>> void quickSort(T[] data,
int min, int max){
if (min < max){
// create partitions
int indexofpartition = partition(data, min, max);
// sort the left partition (lower values)
quickSort(data, min, indexofpartition - 1);
// sort the right partition (higher values)
quickSort(data, indexofpartition + 1, max);
}
}
/**
* Used by the quick sort algorithm to find the partition.
*
* @param data the array to be sorted
* @param min the minimum index in the range to be sorted
* @param max the maximum index in the range to be sorted
*/
private static <T extends Comparable<? super T>> int partition(
T[] data, int min, int max){
T partitionelement;
int left, right;
int middle = (min + max) / 2;
// use the middle data value as the partition element
partitionelement = data[middle];
// move it out of the way for now
swap(data, middle, min);
left = min;
right = max;
while (left < right){
// search for an element that is > the partition element
while (left < right && data[left].compareTo(partitionelement) <= 0)
left++;
// search for an element that is < the partition element
while (data[right].compareTo(partitionelement) > 0)
right--;
// swap the elements
if (left < right)
swap(data, left, right);
}
// move the partition element into place
swap(data, min, right);
return right;
}
/**
* Sorts the specified array of objects using the merge sort
* algorithm.
*
* @param data the array to be sorted
* @param min the integer representation of the minimum value
* @param max the integer representation of the maximum value
*/
public static <T extends Comparable<? super T>> void mergeSort (T[] data, int min, int max){
T[] temp;
int index1, left, right;
/** return on list of length one */
if (min==max)
return;
/** find the length and the midpoint of the list */
int size = max - min + 1;
int pivot = (min + max) / 2;
temp = (T[])(new Comparable[size]);
mergeSort(data, min, pivot); // sort left half of list
mergeSort(data, pivot + 1, max); // sort right half of list
/** copy sorted data into workspace */
for (index1 = 0; index1 < size; index1++)
temp[index1] = data[min + index1];
/** merge the two sorted lists */
left = 0;
right = pivot - min + 1;
for (index1 = 0; index1 < size; index1++){
if (right <= max - min)
if (left <= pivot - min)
if (temp[left].compareTo(temp[right]) > 0)
data[index1 + min] = temp[right++];
else
data[index1 + min] = temp[left++];
else
data[index1 + min] = temp[right++];
else
data[index1 + min] = temp[left++];
}
}
public static <T extends Comparable<? super T>> void PbubbleSort(T[] theArray, int n) {
// ---------------------------------------------------
// Sorts the items in an array into ascending order.
// Precondition: theArray is an array of n items.
// Postcondition: theArray is sorted into ascending
// order. From Prichard&Carrano
// ---------------------------------------------------
boolean sorted = false; // false when swaps occur
for (int pass = 1; (pass < n) && !sorted; ++pass) {
// Invariant: theArray[n+1-pass..n-1] is sorted
// and > theArray[0..n-pass]
sorted = true; // assume sorted
for (int index = 0; index < n-pass; ++index) {
// Invariant: theArray[0..index-1] <= theArray[index]
int nextIndex = index + 1;
if (theArray[index].compareTo(theArray[nextIndex]) > 0) {
// exchange items
T temp = theArray[index];
theArray[index] = theArray[nextIndex];
theArray[nextIndex] = temp;
sorted = false; // signal exchange
} // end if
} // end for
// Assertion: theArray[0..n-pass-1] < theArray[n-pass]
} // end for
} // end bubbleSort
public static <T extends Comparable<? super T>> void PinsertionSort(T[] theArray, int n) {
// ---------------------------------------------------
// Sorts the items in an array into ascending order.
// Precondition: theArray is an array of n items.
// Postcondition: theArray is sorted into ascending
// order. FROM PRITCHARD & CARRANO
// ---------------------------------------------------
// unsorted = first index of the unsorted region,
// loc = index of insertion in the sorted region,
// nextItem = next item in the unsorted region
// initially, sorted region is theArray[0],
// unsorted region is theArray[1..n-1];
// in general, sorted region is theArray[0..unsorted-1],
// unsorted region is theArray[unsorted..n-1]
for (int unsorted = 1; unsorted < n; ++unsorted) {
// Invariant: theArray[0..unsorted-1] is sorted
// find the right position (loc) in
// theArray[0..unsorted] for theArray[unsorted],
// which is the first item in the unsorted
// region; shift, if necessary, to make room
T nextItem = theArray[unsorted];
int loc = unsorted;
while ((loc > 0) &&
(theArray[loc-1].compareTo(nextItem) > 0)) {
// shift theArray[loc-1] to the right
theArray[loc] = theArray[loc-1];
loc--;
} // end while
// Assertion: theArray[loc] is where nextItem belongs
// insert nextItem into sorted region
theArray[loc] = nextItem;
} // end for
} // end insertionSort
public static <T extends Comparable<? super T>> void selectionSort (T[] data){
int min;
T temp;
for (int index = 0; index < data.length-1; index++){
min = index;
for (int scan = index+1; scan < data.length; scan++)
if (data[scan].compareTo(data[min])<0)
min = scan;
/** Swap the values */
temp = data[min];
data[min] = data[index];
data[index] = temp;
}
}
}
主要班级SortPhoneList：
public class SortPhoneList{
/**
* Creates an array of Contact objects, sorts them, then prints
* them.
*/
public static void main (String[] args){
Contact[] friends = new Contact[7];
friends[0] = new Contact ("John", "Smith", "610-555-7384");
friends[1] = new Contact ("Sarah", "Barnes", "215-555-3827");
friends[2] = new Contact ("Mark", "Riley", "733-555-2969");
friends[3] = new Contact ("Laura", "Getz", "663-555-3984");
friends[4] = new Contact ("Larry", "Smith", "464-555-3489");
friends[5] = new Contact ("Frank", "Phelps", "322-555-2284");
friends[6] = new Contact ("Marsha", "Grant", "243-555-2837");
Sorting.quickSort(friends, 0, friends.length-1);
Sorting.mergeSort(friends, 0, friends.length-1);
Sorting.PbubbleSort(friends, 0, friends.length-1);
Sorting.PinsertionSort(friends, 0, friends.length-1);
Sorting.selectionSort(friends, 0, friends.length-1);
for (int index = 0; index < friends.length; index++)
System.out.println (friends[index]);
}
答案 0 :(得分：1)
那些排序算法都运行良好。 （鉴于评论的风格各不相同，我认为你是通过互联网或书籍从不同来源收集的。）
问题在于你以错误的方式调用。请注意，这些不同的方法具有不同的参数：有些只需要对数据进行排序，有些需要数据的长度，有些需要长度减去1。这些信息可以在每种方法顶部的文档中找到。
尝试使用此main方法测试各种排序：
public static void main(String[] args) {
// create random test data
Random random = new Random();
Integer[] data = new Integer[50];
for (int i = 0; i < data.length; i++) {
data[i] = random.nextInt(100);
}
// print unsorted data
System.out.println(Arrays.asList(data));
// uncomment the algorithm you want to test
quickSort(data);
// mergeSort(data, 0, data.length - 1);
// selectionSort(data);
// PinsertionSort(data, data.length);
// PbubbleSort(data, data.length);
// print sorted data
System.out.println(Arrays.asList(data));
}