谁能告诉我私人会员的访问级别？我一直对这段代码感到困惑：为什么可以在外部类的“打印”方法中访问Line类的私有成员k？

public class myClass {
    public static class Line{
        private double k;
        private double b;
        private boolean isVertical;

        public Line(double k, double b, boolean isVertical){
            this.k = k;
            this.b = b;
            this.isVertical = isVertical;
        }

    }

    public static boolean print(Line line){
        System.out.println(line.k);
    }
}