无法从静态上下文引用非静态变量object1 [英] non-static variable object1 cannot be referenced from a static context

问题描述

我在申请上班时遇到了一些麻烦。

I'm having a little trouble getting my application to work.

我得到错误：错误：无法从静态上下文引用非静态变量object1

我确实收到了错误：

error: object_game is not abstract and does not override abstract method keyPressed(KeyEvent) in KeyListener
public class car_game extends JFrame implements Runnable, KeyListener

<但我修正了，因为我需要定义 keyTyped，keyPressed，keyReleased 。

这是我的代码：

public class car_game extends JFrame implements Runnable, KeyListener
{
    public object object1;

    //Main program
    public static void main(String[] args) 
    {
        object1 = new Object() {};


        Thread t = new Thread(new object_game());
        t.start();
    }

推荐答案

您的主要方法是考虑静态，所以它只能访问静态对象，尝试声明你的object1静态：

Your "main" method is considered static and so it can only access static objects, Try declaring your object1 static:

public static Object object1;

编辑：如果你需要2个物品，这样做无害：

edit: if you need 2 objects there is no harm in doing:

public static Object object1;
public static Object object2;

不要在静态字段和静态类（如Singleton）之间混淆。此上下文中的静态（静态Object object1）仅表示每个类car_game的实例中只有该对象的一个​​实例，在上面的情况下，它们将是Object的两个实例（object1和object2），即使您将实例化10 car_game类型的对象。

Do not get mixed up between a static field and a static class (like a Singleton). Static in this context (static Object object1) only means that there is one and only instance of that object per instance of your class car_game, in the case above their would be 2 instance of Object (object1 and object2) even if you would instanciate 10 object of type "car_game".

例如，如果我这样做：

car_game carGameObject1 = new car_game();
car_game carGameObject2 = new car_game();
carGameObject1.setObject1("this is one");

然后：

System.out.println(carGameObject2.getObject1());

它会打印this is one因为object1是静态的所有类的实例字段属于将共享相同的实例。

it would print "this is one" because since object1 is static all instances of the class in which that fields belong will share the same instance.

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