Question

我无法创建Dog对象，我应该能够我不理解编译错误，这是非静态变量，无法从静态上下文中引用

ALTER TEXT SEARCH CONFIGURATION public.russian_extended
        ALTER MAPPING
            FOR asciiword, asciihword, hword_asciipart, hword, hword_part, word
            WITH russian_extended;

Answer 1

您需要将内部类移至Program类之外，否则必须使用new Program().new Dog();实例化它们

public class Program {

   public static void main(String[] args) {
      Dog d = new Dog();
      d.pet();
   }
}

abstract class Animal{
    private String name;
    String latin;
}

class Dog extends Carnivore implements Petable{
    public void pet() {
       System.out.println("bark");
    }
}

abstract class Carnivore extends Animal{}
abstract class Herbivore extends Animal{}

interface Petable{
    public void pet();
}

感谢@ Blokje5和@MC Emperor提供引用和嵌套实例类实例化语法，请对其进行投票。

Answer 2

您的嵌套类不是静态的，它们仅属于该类的成员。要解决此问题，请将import cv2 height, width = input_image.shape[:2] # for horizontal line horizontal_left = (0, int(height / 2)) horizontal_right = (int(width), int(height / 2)) cv2.line(input_image, horizontal_left, horizontal_right, (0, 255, 0), 1) # for vertical vertical_top = (int(width / 2), 0) vertical_bottom = (int(width / 2), int(height)) cv2.line(input_image, vertical_top, vertical_bottom, (0, 255, 0), 1)添加到类声明中。

watch: {
data(newVal) {
  this.columns = newVal.columns;
  this.rows = newVal.rows;
},

更改为

static

现在，您可以使用它们而无需初始化类的成员。

不能引用非静态变量

2 个答案: