threadpoolexecutor如何为Java执行器的可运行性提供参数？

Question

我想用随机整数同时填充nRows * nCols矩阵的单元格。这里的runnable只是一个setter，它将矩阵的一个单元格设置为一个随机整数

public class ConcurrentMatrix {

    private int nRows;
    private int nCols;
    private int[][] matrix = new int[nRows][nCols];

    private MyConcurrentMatrixFiller myConcurrentMatrixFiller;

    public ConcurrentMatrix(int nRows, int nCols, MyConcurrentMatrixFiller filler) {
        this.nRows = nRows;
        this.nCols = nCols;
        this.matrix = new int[nRows][nCols];
        Random r = new Random();
        for (int row=0; row<nRows; row++) {
            for (int col=0; col<nCols; col++) {
                Runnable runnable = new Runnable() {
                    public void run() {
                        matrix[row][col] = r.nextInt(100);
                    }
                };
                filler.execute(runnable); // non-blocking, just depositing runnable in queue.
            }
        }
    }
}

然后filler启动线程池：

public class MyConcurrentMatrixFiller implements Executor {
    BlockingQueue<Runnable> channel = new LinkedBlockingQueue<>();

    @Override
    public void execute(Runnable command) {
        channel.offer(command);
    }

    public MyConcurrentMatrixFiller(int nthreads) {
        for (int i=0; i<nthreads; i++) {
            activate();
        }
    }

    private void activate() {
        new Thread(() -> {
            try {
                while (true) { channel.take().run(); }
            } catch (InterruptedException e) { }
        }).start();
    }   

    public static void main(String[] args) {
        MyConcurrentMatrixFiller filler = new MyConcurrentMatrixFiller(10);
        ConcurrentMatrix cm = new ConcurrentMatrix(10, 10, filler);
    }
}

然而，我的IDE抱怨说row和col索引应该是最终的。但是我需要每个runnable都关心它自己的单元格，那么我如何向runnable提供这些值呢

Answer 1

最好的解决方案是创建一个新类来扩展runnable并接受它需要使用的所有参数。在这种情况下，它是矩阵，随机种子r，行和列。 在您的情况下，它将如下所示：

你的新班级：

public class MyExecutor extends Runnable {
    private final int[][] matrix;
    private final Random r;
    private final int row;
    private final int col;
    public MyExecutor( int[][] matrix, Random r, int row, int col ) {
        this.matrix = matrix;
        this.r = r;
        this.row = row;
        this.col = col;
    }

    @Override
    public void run() {
        matrix[row][col] = r.nextInt(100);
    }
}

以及您的ConcurrentMatrix：

public ConcurrentMatrix(int nRows, int nCols, MyConcurrentMatrixFiller filler) {
    this.nRows = nRows;
    this.nCols = nCols;
    this.matrix = new int[nRows][nCols];
    Random r = new Random();
    for (int row=0; row<nRows; row++) {
        for (int col=0; col<nCols; col++) {
            Runnable runnable = new MyExecutor( row, col );
            filler.execute(runnable); // non-blocking, just depositing runnable in queue.
        }
    }
}