java - java中if比较的长列表

Question

我需要比较两个对象。如果存在差异，我需要根据特定差异记录它并返回 true。

例如:

private boolean compTwoObjects(Object objA, Object ObjB) {
   if(objA.getType() != objB.getType()) {
      logTheDifference("getType is differing");
      return true;
   }
                   .
                   .
                   .
   // Now this could invoke other composite methods
   if(checkFont(objA.getFont(), objB.getFont()) {
      logTheDifference("Font is differing");
      return true;
   }
}


private boolean checkFont(Font fontObjA, Font fontObjB) {
   if(fontObjA.getBold() != fontObjB.getBold()) {
      logTheDifference("font bold formatting differs");
      return true;
   }
                   .
                   .
                   .
   if(fontObjA.getAllCaps() != fontObjB.getAllCaps()) {
      logTheDifference("font all caps formatting differs");
      return true;
   }
                   .
                   .
                   .
   if(checkBorderDiff(fontObjA.getBorder(), fontObjB.getBorder())) {
      logTheDifference("border diff");
      return true;
   }
}

private boolean checkBorderDiff(Border borderObjA, Border borderObjB) {
    if (borderObjA.getColor() != null || borderObjB.getColor() != null) {
       if (!borderObjA.getColor().equals(borderObjB.getColor())) {
            logIt("border color differing");
            return true;
        }
    }

    if (borderObjA.getDistanceFromText() != borderObjB.getDistanceFromText()) {
        logIt("distance of the border from text or from the page edge in points differing");
        return true;
    }

    if (borderObjA.isVisible() != borderObjB.isVisible()) {
        logIt("border visibility differing");
        return true;
    }

    if (borderObjA.getLineStyle() != borderObjB.getLineStyle()) {
        logIt("line style differing for border");
        return true;
    }

    if (borderObjA.getLineWidth() != borderObjB.getLineWidth()) {
        logIt("border width in points differing");
        return true;
    }

    if (borderObjA.getShadow() != borderObjB.getShadow()) {
        logIt("border shadow differing");
        return true;
    }
}

//And it is going like this.

我的问题是我想避免在方法中使用多个 if 语句。我还想记录与特定差异对应的消息。

我在 stackoverflow 上读到过一些类似的问题，这些问题是通过命令模式或 HashMap 解决的。但它们不包括比较。

我想重构我的代码以摆脱一系列的 if。

Answer 1

有一个由泛型支持的比较器系统。每个比较器也会知道下一行是什么。例如:

interface IComparer<T> {
    boolean areDifferent (T first, T second);
}

class FontComparer implements IComparer<Font> {
    @Override
    public boolean areDifferent(Font first, Font second) {
        // Compare fonts start
        // ..
        // Compare fonts end
        return new BorderComparer().areDifferent(first.getBorder(), second.getBorder());
    }
}


class BorderComparer implements IComparer<Border> {

    @Override
    public boolean areDifferent(Border first, Border second) {
        //Do border comparison alone
        return false;
    }
}

您现在可以设置一个比较器链，并在比较失败时退出。否则，比较转到链中的下一个比较器。

客户端代码最终将如下所示:

    Object one = new Object();
    Object two = new Object();
    new ObjectComparer().areDifferent(one, two);