java - Issues with code in overriden abstract method in Java enum

Question

I'm trying to implement an abstract method in an enum as in code below, but Eclipse is underlining the .getUrls method and displaying the tooltip "this method requires a body instead of a semicolon, two quick fixes: (add body, add 'abstract' modifier)", none of which make sense to me.

The method itself is just a normal method that works in other classes.

What I'm doing wrong?

public enum Site {
    PORTAL1 ("http://www.somedomain.net") {
        @Override
        public void method() {
            ArrayList<String> urlList = urlManager.getUrls(int number);
        }
    };
    // more values

    public abstract void method();
    private final String baseUrl;
    private UrlManager urlManager;

    private Site(final String baseUrl) {
        this.baseUrl = baseUrl;
        urlManager = new UrlManager();
    }
}

Answer 1

一个问题是以下行在语法上无效：

ArrayList<String> urlList = urlManager.getUrls(int number);
                                               ^^^^^^^^^^ HERE

另一个问题是您无法访问from的非static成员。您要么需要 make ，要么让每个子类都有自己的.SitePORTAL1UrlManager staticSiteUrlManager

Answer 2

除了明显的问题之外int number，您不能urlManager从枚举实例中引用。您可以对其进行保护，以便可以从每个实例访问它：

public enum Site {

    PORTAL1("http://www.somedomain.net") {
        @Override
        public void method() {
            ArrayList<String> urlList = urlManager.getUrls(5);
        }
    };
    // more values

    public abstract void method();
    private final String baseUrl;
    protected UrlManager urlManager;

    private Site(final String baseUrl) {
        this.baseUrl = baseUrl;
        urlManager = new UrlManager();
    }
}

Answer 3

由于枚举类未声明为抽象类，甚至可能不想被称为抽象类，请执行以下操作：

public void method() {
    }

非抽象类不能有抽象方法。

Answer 4

你有一些不正确的语法：

urlManager.getUrls(int number);

你是在声明一个变量，你应该在其中传递一个参数。另外，在哪里urlManager声明？