[英]Why am I receiving a Stack overflow error?
以下代碼模擬尋找最接近的對,但是當我生成大於 250 的隨機數量的對時,它會引發堆棧溢出錯誤。 但是 250 雙和任何偶數以下似乎都可以正常工作。 有任何想法嗎?
在 if 語句下遞歸調用 ComparePoints 時發生錯誤。
public class Divide {
Point2D closest1;
Point2D closest2;
double Distance = Double.MAX_VALUE;
public Divide(Point2D[] RandArray){
SortArray s = new SortArray();
RandArray = s.SortPointsX(RandArray);
SplitAndConquer(RandArray);
}
private double ComparePoints(Point2D a, Point2D b, Point2D[] s,
int CurrentPoint, int NextPoint){
if(s[CurrentPoint] != null && s[NextPoint] != null){
if (Distance > a.distance(b) &&
(a.getX() != b.getX() || a.getY() != b.getY())){
Distance = a.distance(b);
closest1 = new Point2D.Double(a.getX(), a.getY());
closest2 = new Point2D.Double(b.getX(), b.getY());
}
if (NextPoint == (s.length - 1)){
NextPoint = s.length - ((s.length - 1) - CurrentPoint);
CurrentPoint++;
}
if (CurrentPoint != (s.length - 1)){
if (NextPoint != (s.length - 1)){
NextPoint++;
ComparePoints(s[CurrentPoint], s[NextPoint],
s, CurrentPoint, NextPoint);
}
}
if (CurrentPoint == (s.length - 1)){
CurrentPoint = 0;
NextPoint = 0;
}
}
return Distance;
}
private void SplitAndConquer(Point2D[] RandArray){
double median = RandArray[RandArray.length/2].getX();
int countS1 = 0;
int countS2 = 0;
boolean exact = false;
int CurrentPoint = 0;
int NextPoint = 0;
Point2D[] s1 = new Point2D[RandArray.length/2];
Point2D[] s2 = new Point2D[RandArray.length/2];
for (int i = 0; i < RandArray.length; i++){
if (RandArray[i].getX() < median){
s1[countS1] = RandArray[i];
countS1++;
}
else if (RandArray[i].getX() > median){
s2[countS2] = RandArray[i];
countS2++;
}
else if (RandArray[i].getX() == median && exact == false){
s2[countS2] = RandArray[i];
exact = true;
countS2++;
}
else if (RandArray[i].getX() == median && exact == true) {
s1[countS1] = RandArray[i];
exact = false;
countS2++;
}
}
if (s1[0] != null && s1[1] != null){
Distance = ComparePoints(s1[0], s1[1], s1,
CurrentPoint, NextPoint);
Distance = ComparePoints(s2[0], s2[0], s2,
CurrentPoint, NextPoint);
}else{
System.out.println
("One of the subsets does not contain enough points!");
}
CheckMid(RandArray, Distance, median, CurrentPoint, NextPoint);
PrintClosest();
}
private void PrintClosest() {
System.out.println("The closest pair found using Divide "
+ "And Conquer is at ("
+ closest1.getX() + " " + closest1.getY() + "), and ("
+ closest2.getX() + " " + closest2.getY() + ")");
System.out.println("The distance between the pairs is: " + Distance);
}
private void CheckMid(Point2D[] randArray, double d, double m,
int current, int next) {
int MidCount = 0;
Point2D[] MidArray = new Point2D[randArray.length];
for(int i = 0; i < randArray.length; i++){
if(randArray[i].getX() > (m - d) &&
randArray[i].getX() < (m + d)){
MidArray[MidCount] = randArray[i];
MidCount++;
}
}
if (MidArray[0] != null && MidArray[1] != null){
ComparePoints(MidArray[0], MidArray[1], MidArray,
current, next);
}
}
}
聽起來您超出了為程序分配的堆棧內存量。 您可以使用 -Xss 選項更改堆棧大小。 例如java -Xss 8M
將堆棧大小更改為 8MB 並運行您的程序。
Java內部有調用棧,將方法調用存儲為棧幀。 它以 LIFO 方式處理這些方法調用(幀)。 創建新線程(在您的情況下是主線程)時,會為該線程分配固定數量的堆棧和堆內存。 因此,每當調用堆棧耗盡時,我們都會收到 stackoverflow 錯誤。 在您的情況下,遞歸調用的數量已超過調用堆棧的大小,因此您收到錯誤消息。
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