java - 非静态/静态变量错误

Question

我正在制作一个程序，可以获取裁判分数并给出平均值，我认为我做错了一个变量。我收到错误消息:

non-static variable difficulty cannot be referenced from a static context
difficulty = keyboard.nextDouble;

我已经尝试将它移到 main 方法之上并向它添加“static”，但它似乎仍然给我带来问题。还有什么我可以做的吗？这是它的部分代码

import java.util.Scanner;
public class CH6PA
{
private double difficulty;
private int score;
private double[] average;

public static void main(String[]args)
{
    Scanner keyboard = new Scanner (System.in);

    do
    {
        System.out.println("Enter the level of difficulty (1.2-3.8)");
    difficulty = keyboard.nextDouble;
    }
        while (difficulty>1.2 || difficulty<3.8);


    int judge = new int[7];


    for(int i = 0; i<judge.length; i++)
    {

Answer 1

其他答案是关于将事物更改为静态的，您应该避免在静态变量中具有可变状态这是编程的 101 - 它本质上是全局变量。

import java.util.Scanner;
public class CH6PA
{
private double difficulty;
private int score;
private double[] average;

public static void main(String[]args)
{
    CH6PA ch6pa = new CH6PA();
    ch6pa.doSomething();
}

private void doSomething() {
    Scanner keyboard = new Scanner (System.in);

    do {
        System.out.println("Enter the level of difficulty (1.2-3.8)");
        difficulty = keyboard.nextDouble;
    } while (difficulty>1.2 || difficulty<3.8);

    int judge = new int[7];

    for(int i = 0; i<judge.length; i++) {
    }