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我想使用合併排序實現多線程。我在創建新線程的時候將數組減半。
該數組排序取決於： [數組的大小] vs [我創建新線程的次數] 例如：如果我讓它在大小爲70的數組上創建僅兩個線程，數組將被排序，但如果我讓它創建6，它會回來unsorted。有一兩件事我想這可能是是線程不同步時間，但我用threadName.join（）Java線程問題，使用Runnable或線程
這裏是一些代碼：merge.java
import java.util.Random;
public class merge implements Runnable {
int[] list;
int length;
int countdown;
public merge(int size, int[] newList, int numberOfThreadReps, int firstMerge) {
length = size;
countdown = numberOfThreadReps;
list = newList;
if (firstMerge == 1)
threadMerge(0, length - 1);
}
public void run() {
threadMerge(0, length - 1);
}
public void printList(int[] list, int size) {
for (int i = 0; i < size; i++) {
System.out.println(list[i]);
}
}
public void regMerge(int low, int high) {
if (low < high) {
int middle = (low + high)/2;
regMerge(low, middle);
regMerge(middle + 1, high);
mergeJoin(low, middle, high);
}
}
public void mergeJoin(int low, int middle, int high) {
int[] helper = new int[length];
for (int i = low; i <= high; i++) {
helper[i] = list[i];
}
int i = low;
int j = middle + 1;
int k = low;
while (i <= middle && j <= high) {
if (helper[i] <= helper[j]) {
list[k] = helper[i];
i++;
} else {
list[k] = helper[j];
j++;
}
k++;
}
while (i <= middle) {
list[k] = helper[i];
k++;
i++;
}
helper = null;
}
public void threadMerge(int low, int high) {
if (countdown > 0) {
if (low < high) {
countdown--;
int middle = (low + high)/2;
int[] first = new int[length/2];
int[] last = new int[length/2 + ((length % 2 == 1) ? 1 : 0)];
for (int i = 0; i < length/2; i++)
first[i] = list[i];
for (int i = 0; i < length/2 + ((length % 2 == 1) ? 1 : 0); i++)
last[i] = list[i + length/2];
merge thread1 = new merge(length/2, first, countdown, 0);// 0
// is
// so
// that
// it
// doesn't
// call
// threadMerge
// twice
merge thread2 = new merge(length/2
+ ((length % 2 == 1) ? 1 : 0), last, countdown, 0);
Thread merge1 = new Thread(thread1);
Thread merge2 = new Thread(thread2);
merge1.start();
merge2.start();
try {
merge1.join();
merge2.join();
} catch (InterruptedException ex) {
System.out.println("ERROR");
}
for (int i = 0; i < length/2; i++)
list[i] = thread1.list[i];
for (int i = 0; i < length/2 + ((length % 2 == 1) ? 1 : 0); i++)
list[i + length/2] = thread2.list[i];
mergeJoin(low, middle, high);
} else {
System.out.println("elsd)");
}
} else {
regMerge(low, high);
}
}
}
proj4.java
import java.util.Random;
public class proj4 {
public static void main(String[] args) {
int size = 70000;
int threadRepeat = 6;
int[] list = new int[size];
list = fillList(list, size);
list = perm(list, size);
merge mergy = new merge(size, list, threadRepeat, 1);
// mergy.printList(mergy.list,mergy.length);
for (int i = 0; i < mergy.length; i++) {
if (mergy.list[i] != i) {
System.out.println("error)");
}
}
}
public static int[] fillList(int[] list, int size) {
for (int i = 0; i < size; i++)
list[i] = i;
return list;
}
public static int[] perm(int[] list, int size) {
Random generator = new Random();
int rand = generator.nextInt(size);
int temp;
for (int i = 0; i < size; i++) {
rand = generator.nextInt(size);
temp = list[i];
list[i] = list[rand];
list[rand] = temp;
}
return list;
}
}
so TL; DR我的數組沒有通過基於數組大小和使用線程拆分數組次數的多線程合併排序進行排序......爲什麼是這樣？