[英]Java Array sort by means of a comparator
完整的代碼可以在以下位置找到: https : //skydrive.live.com/redir?resid=7B7D2F11B13EF9C9!54468&authkey=!AD4fD8sGgc7oJIE
這是代碼的一部分:
g_sorted = 0;
for (int l_loop = 0; l_loop < l_length; l_loop++)
{
if (!l_IntegerArray[l_loop].equals(g_exclude))
{
g_tag[g_sorted] = l_loop;
g_tosort_Integer[g_sorted] = l_IntegerArray[l_loop];
g_sorted++;
}
} // for (int l_loop = 0; l_loop < p_toSort; l_loop++)
Arrays.sort
(g_tag, 0, g_sorted, new Comparator<Integer>()
{
public int compare(Integer i1, Integer i2)
{
return Integer.compare(g_tosort_Integer[i1], g_tosort_Integer[i2]);
}
}
);
g_tosort_Integer,g_tag,g_tosort_Integer是“整數”。 g_exclude用於排除不能屬於排序的項目。
當沒有項目被排除時(沒有項目的值等於g_exclude或if語句被注釋),一切正常。
當排除1個或多個項目時,我得到NullPointerException:
Exception in thread "main" java.lang.NullPointerException
at TestSort$1.compare(TestSort.java:53)
at TestSort$1.compare(TestSort.java:50)
at java.util.TimSort.binarySort(TimSort.java:265)
at java.util.TimSort.sort(TimSort.java:190)
at java.util.Arrays.sort(Arrays.java:727)
at TestSort.<init>(TestSort.java:48)
at TestSort.main(TestSort.java:71)
誰可以給我解釋一下這個 ? 謝謝。
這是怎么解決的。 我保留了您的類的“結構”,但是我自由地更改了變量名,以使我的工作更加清晰。 您詢問了如何對數組進行排序,而不改變元素的順序,而是改變其上的索引。
這是代碼。
public class TestSort {
int c_maxSort = 10000;
Integer[] unsortedAndFiltered = new Integer[c_maxSort];
Integer[] index = new Integer[c_maxSort];
public TestSort() {
Integer exclude = 0;
int newPosition;
int lengthOfOriginalArray;
Integer[] originalArray = { 5, 3, 0, 2, 7, 1, 5, 6, 8, 4 };
lengthOfOriginalArray = originalArray.length;
System.out.print("Original: ");
for (int i = 0; i < lengthOfOriginalArray; i++)
System.out.print(originalArray[i] + " ");
System.out.println(" - Length: " + lengthOfOriginalArray);
newPosition = 0;
for (int i = 0; i < lengthOfOriginalArray; i++) {
if (!originalArray[i].equals(exclude)) {
index[newPosition] = newPosition;
unsortedAndFiltered[newPosition] = originalArray[i];
newPosition++;
}
}
System.out.println("Tags: ");
for (int i = 0; i < newPosition; i++)
System.out.print(index[i] + " ");
System.out.println("");
System.out.println("Unsorted numbers: ");
for (int l_loop = 0; l_loop < newPosition; l_loop++)
System.out.print(unsortedAndFiltered[l_loop] + " ");
System.out.println("");
int deleted = lengthOfOriginalArray - newPosition;
Arrays.sort(index, 0, newPosition, new IndirectedComparator(unsortedAndFiltered, index));
System.out.println("Sorted Tags: ");
for (int i = 0; i < newPosition; i++)
System.out.print(index[i] + " ");
System.out.println("");
System.out.println("Sorted Numbers: ");
for (int i = 0; i < newPosition; i++)
System.out.print(unsortedAndFiltered[index[i]] + " ");
System.out.println("");
}
public static void main(String[] args) {
new TestSort();
}
}
比較器的編碼如下:
public class IndirectedComparator implements Comparator<Integer> {
private Integer[] array;
private Integer[] index;
public IndirectedComparator(Integer [] array, Integer[] index){
this.array = array;
this.index = new Integer[index.length];
System.arraycopy(index, 0, this.index, 0, index.length);
}
@Override
public int compare(Integer i1, Integer i2) {
return Integer.compare(array[index[i1]], array[index[i2]]);
}
}
這是我的處決:
Original: 5 3 0 2 7 1 5 6 8 4 - Length: 10
Tags:
0 1 2 3 4 5 6 7 8
Unsorted numbers:
5 3 2 7 1 5 6 8 4
Sorted Tags:
4 2 1 8 0 5 6 3 7
Sorted Numbers:
1 2 3 4 5 5 6 7 8
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