java - Arrays.setAll 不适用于 boolean 值

Question

我想创建一个大数组，并想尝试一些 lambda，但出于某种原因:

cells = new boolean[this.collums][this.rows];
IntStream.range(0, cells.length).forEach(x -> Arrays.setAll(cells[x], e -> MathX.fastNextInt(1) == 0 ? true : false));

不会工作，即使那样:

cells = new boolean[this.collums][this.rows];
IntStream.range(0, cells.length).forEach(x -> Arrays.setAll(cells[x], e -> true));

剂量不起作用。

编译器错误是:

Type mismatch: cannot convert from boolean to T

和:

The method setAll(T[], IntFunction) in the type Arrays is not applicable for the arguments (boolean[], ( e) -> {})

Answer 1

因为应该是引用类型:Boolean:

Boolean[][] cells = new Boolean[this.collums][this.rows];

---

UPD:如果你想使用boolean类型，你必须为原始 boolean 类型编写你自己的setAll()实现:

interface BooleanUnaryOperator {
    boolean apply(int x);
}

public static void setAll(boolean[] array, BooleanUnaryOperator generator) {
    for (int i = 0; i < array.length; i++)
        array[i] = generator.apply(i);
}

UPD-2:作为@Holger提到，名称 BooleanUnaryOperator 具有误导性，为此目的最好使用现有的类 - IntPredicate . (在这种情况下，将 array[i] = generator.apply(i); 更改为 array[i] = generator.test(i);)