Question

我遇到的问题是将这段代码转换为Java8流。基本上我有一个死的（假）或活的（真）单元格列表，我需要检查给定的邻居有多少细胞

private static int checkMyLivingNeighbours(Cell cell,List<Cell> currentcells){

    int neighbours = 0;

    for (int y = cell.getY() - 1; y <= cell.getY() + 1; y++) {
        for (int x = cell.getX() - 1; x <= cell.getX() + 1; x++) {
            if(x!=cell.getX() || y!=cell.getY()){
                for (Cell nowcell : currentcells) {
                    if (nowcell.getX() == x && nowcell.getY() == y) {
                        if (nowcell.getStatus()) {
                            neighbours++;
                        }
                    }
                }
            }

        }
    }
    return neighbours;
}

我尝试过这样的事情

private static void checkaliveneighbours(Cell cell,List<Cell> generation){

    generation.stream().forEach(n->IntStream.range(cell.getY()-1,cell.getY()+1).
                    forEach(y -> IntStream.range(cell.getX()-1,cell.getX()+1)
                            .forEach(x->{if(n.getX()==x && n.getY()==y && n.getStatus())System.out.println(n.getDisplaychar());})));;//
}

我称之为

    checkaliveneighbours(generation.get(0),generation);

所以我确实获得了活CELL的打印但我实际上需要传入CELL周围的活CELLS的总数nr而不仅仅是传入的单元格是否存活。因此，如何响应地（基于传入的单个单元）限制流（仅周围的单元）中的元素数量的问题。

这是细胞类

public class Cell {

private int x;
private int y;
private boolean alive;

public Cell(){}


public Cell(String x, String y, boolean alive ) {
    this.x = Integer.valueOf(x);
    this.y = Integer.valueOf(y);
    this.alive = alive;

}

public int getX() {
    return x;
}

public void setX(String x) {
    this.x = Integer.valueOf(x);
}

public int getY() {
    return y;
}

public void setY(String y) {
    this.y = Integer.valueOf(y);
}

public boolean getStatus() {
    return alive;
}

public void setStatus(boolean status) {
    this.alive = status;
}

public char getDisplaychar() {

    if(getStatus())
        return 'X';
    else
        return '.';
}


}

Answer 1

如果我理解正确，通过＆＃34;限制＆＃34;你的意思是使用#import "UIImage+Zoom.h" @implementation UIImage (Zoom) /* * @brief resizeImage * @param newsize the dimensions（pixel） of the output image */ - (UIImage*)resizeImageToSize:(CGSize)newSize resizeMode:(SvResizeMode)resizeMode { CGRect drawRect = [self caculateDrawRect:newSize resizeMode:resizeMode]; UIGraphicsBeginImageContext(newSize); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextClearRect(context, CGRectMake(0, 0, newSize.width, newSize.height)); CGContextSetInterpolationQuality(context, 0.8); [self drawInRect:drawRect blendMode:kCGBlendModeNormal alpha:1]; UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image; } // caculate drawrect respect to specific resize mode - (CGRect)caculateDrawRect:(CGSize)newSize resizeMode:(SvResizeMode)resizeMode { CGRect drawRect = CGRectMake(0, 0, newSize.width, newSize.height); CGFloat imageRatio = self.size.width / self.size.height; CGFloat newSizeRatio = newSize.width / newSize.height; switch (resizeMode) { case enSvResizeScale: { // scale to fill break; } case enSvResizeAspectFit: // any remain area is white { CGFloat newHeight = 0; CGFloat newWidth = 0; if (newSizeRatio >= imageRatio) { // max height is newSize.height newHeight = newSize.height; newWidth = newHeight * imageRatio; } else { newWidth = newSize.width; newHeight = newWidth / imageRatio; } drawRect.size.width = newWidth; drawRect.size.height = newHeight; drawRect.origin.x = newSize.width / 2 - newWidth / 2; drawRect.origin.y = newSize.height / 2 - newHeight / 2; break; } case enSvResizeAspectFill: { CGFloat newHeight = 0; CGFloat newWidth = 0; if (newSizeRatio >= imageRatio) { // max height is newSize.height newWidth = newSize.width; newHeight = newWidth / imageRatio; } else { newHeight = newSize.height; newWidth = newHeight * imageRatio; } drawRect.size.width = newWidth; drawRect.size.height = newHeight; drawRect.origin.x = newSize.width / 2 - newWidth / 2; drawRect.origin.y = newSize.height / 2 - newHeight / 2; break; } default: break; } return drawRect; }来过滤邻居。然后你要总结所有生活的邻居。我首先定义一个方法，它将返回指定的单元格是否是相邻单元格：

Stream.filter()

然后您可以轻松过滤列表并计算总和，如下所示：

private static boolean isNeighbor(final Cell cell, final Cell candidate) {
      for (int y = cell.getY() - 1; y <= cell.getY() + 1; y++) {
        for (int x = cell.getX() - 1; x <= cell.getX() + 1; x++) {
            if (x != cell.getX() || y != cell.getY()) {
                if (candidate.getX() == x && candidate.getY() == y) {
                    return true;
                }
            }
        }
    }
    return false;
}

修改：如果您正在为int sum = generation.stream() .filter(c -> isNeighbor(cell, c)) .mapToInt(c -> c.getStatus() ? 1 : 0) .sum();寻找纯Java 8解决方案：

isNeighbor

如何响应地限制流中的元素数量？Java8

1 个答案: