java - 错误消息 'Cannot be resolved or is not a field'

Question

现在我正在研究责任链设计模式并使用 Eclipse .

我正在尝试编译此代码，但出现编译错误“isLast 无法解析或不是字段”:

public class OverFive implements Discount {
    private Discount next; //
    public boolean isLast = false;

    public void setNext(Discount next, boolean Last) {
        this.next = next;
        this.next.isLast = Last; // Here is the error.
    }

    public double DoDiscount(Budget budget) {
        if (budget.getValue() > 500) {
            return budget.getValue() * 0.10;
        }
        if (this.next.isLast == false) {
            return next.DoDiscount(budget);
        }
        else {
            return 0;
        }
    }
}

现在，界面如下:

public interface Discount {

    double DoDiscount(Orcamento orcamento);
        void setNext(Discount next, boolean Last);
    }

Answer 1

这里有一个建议:研究 Sun Java 编码标准并牢记在心。在这个小代码示例中，您太频繁地破坏它们了。

Java区分大小写:“discount”与“Discount”不同； “dodiscount”与“DoDiscount”不同。

public interface Discount {

    double doDiscount(Orcamento orcamento);
    void setNext(Desconto next, boolean last);
    void setLast(boolean last);
} 

以及实现:

public class OverFive implements Discount {
    private Desconto next;
    private boolean last = false;

    public void setLast(boolean last) {
        this.last = last;
    }

    public void setNext(Desconto next, boolean last) {
        this.next = next;
        this.setLast(last);
      }

    // this method is utter rubbish.  it won't compile.
    public double doDiscount(Orcamento budget){
        if (budget.getValue() > 500){
            return budget.getValue() * 0.10;
        }if (this.next.isLast == false){
            return next.discount(budget);
        }else{
            return 0;
        }   
    }
}

我认为这段代码有点令人困惑。难怪你会遇到问题。