避免使用java流-android

Question

我有一段代码，但我想避免使用java流，因为android不支持流。这是我的代码：

import java.util.Arrays;
import static java.util.Arrays.stream;
import java.util.concurrent.*;
public class VogelsApproximationMethod {
    final static int[] demand = {30, 20, 70, 30, 60};
    final static int[] supply = {50, 60, 50, 50};
    final static int[][] costs = {{16, 16, 13, 22, 17}, {14, 14, 13, 19, 15},
    {19, 19, 20, 23, 50}, {50, 12, 50, 15, 11}};
    final static int nRows = supply.length;
    final static int nCols = demand.length;
    static boolean[] rowDone = new boolean[nRows];
    static boolean[] colDone = new boolean[nCols];
    static int[][] result = new int[nRows][nCols];
    static ExecutorService es = Executors.newFixedThreadPool(2);
    public static void main(String[] args) throws Exception {
        int supplyLeft = stream(supply).sum();
        int totalCost = 0;
        while (supplyLeft > 0) {
            int[] cell = nextCell();
            int r = cell[0];
            int c = cell[1];
            int quantity = Math.min(demand[c], supply[r]);
            demand[c] -= quantity;
            if (demand[c] == 0)
                colDone[c] = true;
            supply[r] -= quantity;
            if (supply[r] == 0)
                rowDone[r] = true;
            result[r][c] = quantity;
            supplyLeft -= quantity;
            totalCost += quantity * costs[r][c];
        }
        stream(result).forEach(a -> System.out.println(Arrays.toString(a)));
        System.out.println("Total cost: " + totalCost);
        es.shutdown();
    }

如果有人能帮我，我将不胜感激，因为我不明白stream是如何工作的。

Answer 1

这很容易，你可以像Mike M在他的评论中建议的那样使用for循环，见下面的例子：

int supplyLeft = 0;
int[] supply = {50, 60, 50, 50};
for (int i : supply) {
    supplyLeft += i;
}
System.out.println(supplyLeft); 

取代

int supplyLeft = stream(supply).sum();

如果你也不想要foreach，那么

int supplyLeft = 0;
for (int i = 0; i < supply.length; i++) {
    supplyLeft += supply[i];
}
System.out.println(sum); 

至于在2D数组中迭代并替换如下所示的java-8流，则涉及

stream(result).forEach(a -> System.out.println(Arrays.toString(a)));

您可以根据需要使用for loop或Arrays.deepToString()，请参阅以下示例：

//assume your array is below, you can replace it with results everywhere
int[][] costs= { { 16, 16, 13, 22, 17 }, { 14, 14, 13, 19, 15 },
                { 19, 19, 20, 23, 50 }, { 50, 12, 50, 15, 11 } };
for (int i = 0; i < costs.length; i++) {
    System.out.println(Arrays.toString(costs[i]));
}

以上for loop将以以下方式打印阵列

[16, 16, 13, 22, 17]
[14, 14, 13, 19, 15]
[19, 19, 20, 23, 50]
[50, 12, 50, 15, 11]

如果使用Arrays.deepToString(costs)，则会得到如下所示的输出：

[[16, 16, 13, 22, 17], [14, 14, 13, 19, 15], [19, 19, 20, 23, 50], [50, 12, 50, 15, 11]]

以上替换