如何知道是否arraylist包含对象的属性值？[重复]

Question

我想找到属性Numb中的ArrayList网格是否包含某个值。然后我想获取包含该值的条目的索引。

public class Grid {
    public int numb;

    public GridSeg(int numb) {
        this.numb = numb;
    }
}

public ArrayList<Grid> grids = new ArrayList<Grid>();

for (int i = 0; i < 6; i++) {
    Grid grid = new Grid(i);
    grids.add(grid);
}

// pseudo code since I don't know how it is done
if (grids.numb.contains(12)) {
    if (grid.numb == 12) //get grid index
}

Answer 1

你可以通过流来实现它

    ArrayList<Grid> grids = new ArrayList<>();
    Grid grid = grids.stream().filter(l -> l.numb == 12).findFirst().orElse(null);
    int index = grids.indexOf(grid);