java - Eclipse 中的 java 中未定义构造函数，尽管已定义

Question

这个问题已经有答案了:

What causes error "No enclosing instance of type Foo is accessible" and how do I fix it? (11 个回答)

已关闭 7 年前。

请帮忙....我是 Java 新手。我正在尝试编写一个包含类“point”的代码到 Eclipse(Luna) 中的公共(public)类“PeterAndSnowBlower”中。我也尝试过在“point”类中公开变量 x, y ，但它给出了相同的错误。我还在构造函数中使用了 this.x 和 this.y 而不是 x 和 y

这是我的代码:

import java.util.*;
public class PeterAndSnowBlower {
    class point{
        int x;
        int y;
        public point() {
            x = y = 0;
        }
        public point(int a, int b){
            x = a;
            y = b;
        }
        public point(point p) {
            x = p.x;
            y = p.y;
        }
        public double distance(point P){
            int dx = x - P.x;
            int dy = y - P.y;
            return Math.sqrt(dx*dx + dy*dy);
        }
    }
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int n, x, y;
        point P = new point(0, 0);
        n = in.nextInt();
        P.x = in.nextInt();
        P.y = in.nextInt();
        Vector<point>points = new Vector<point>();
        for(int i = 0; i < n; i++){
            x = in.nextInt();
            y = in.nextInt();
            points.add(new point(x, y));
        }
        double r1, r2;
        r1 = r2 = P.distance(points.get(0));
        for(point point:points){
            r1 = Math.max(r1, P.distance(point));
        }

    }
}

错误是:

Multiple markers at this line
- No enclosing instance of type PeterAndSnowBlower is accessible. Must qualify the allocation with an enclosing instance of type PeterAndSnowBlower (e.g. 
 x.new A() where x is an instance of PeterAndSnowBlower).
- The constructor PeterAndSnowBlower.point(int, int) is undefined

Answer 1

除非内部类定义为static，否则无法从外部类的静态方法实例化它。 非静态类需要this对外部类的引用。

这里将此类声明为static是有意义的。显然它不是指外部类。