java – foreach语句中的块必须只有一行吗？

2019年8月4日 150次阅读

我正在阅读一本名为
Clean Code -A Handbook of Agile Software Craftsmanship的书,由Robert C. Martin撰写,在他的书中,他提供了许多有关如何编写优秀Java代码的有用技巧.

其中一个提示是：

Blocks within if statements, else statements, for statements, and so
on should be one line long. Probably that line should be a function
call. Not only does this keep the enclosing function small, but it
also adds documentary value because the function called within the
block can have a nicely descriptive name

对我来说这是非常奇怪的提示,因为从这段代码：

public Map<String, List<Issue>> mapComponentToIssueList(List<Issue> issues) {
    Map<String, List<Issue>> map = new HashMap<String, List<Issue>>();

    for (Issue issue : issues) {
        String componentName = issue.getComponents().iterator().next().getString("name");
        if (map.containsKey(componentName)) {
            map.get(componentName).add(issue);
        } else {
            List<Issue> list = new ArrayList<Issue>();
            list.add(issue);
            map.put(componentName, list);
        }
    }
    return map;

}

使用这个原则我得到了这个：

public Map<String, List<Issue>> mapComponentToIssueList(List<Issue> issues) {
    Map<String, List<Issue>> componentNameIssueListMap = new HashMap<String, List<Issue>>();
    for (Issue issue : issues) {
        populateMapWithComponenNamesAndIssueLists(componentNameIssueListMap, issue);
    }
    return componentNameIssueListMap;
}

private void populateMapWithComponenNamesAndIssueLists(Map<String, List<Issue>> componentNameIssueListMap, Issue issue) {
    String componentName = getFirstComponentName(issue);
    if (componentNameIssueListMap.containsKey(componentName)) {
        componentNameIssueListMap.get(componentName).add(issue);
    } else {
        putIssueListWithNewKeyToMap(componentNameIssueListMap, issue, componentName);
    }
}

private void putIssueListWithNewKeyToMap(Map<String, List<Issue>> componentNameIssueListMap, Issue issue, String componentName) {
    List<Issue> list = new ArrayList<Issue>();
    list.add(issue);
    componentNameIssueListMap.put(componentName, list);
}

private String getFirstComponentName(Issue issue) {
    return issue.getComponents().iterator().next().getString("name");
}

所以基本上代码的大小增加了一倍.它有用吗？ – 也许.

我的例子中的代码是什么叫做clean？我究竟做错了什么？你们怎么看待这个？

最佳答案 坦率地说,我认为这个提示是愚蠢的,因为它是如此极端.

就个人而言,如果我要对你的功能做任何事情,我会改变它：

public Map<String, List<Issue>> mapComponentToIssueList(List<Issue> issues) {
    Map<String, List<Issue>> map = new HashMap<String, List<Issue>>();

    for (Issue issue : issues) {
        String componentName = issue.getComponents().iterator().next().getString("name");
        List<Issue> list = map.get(componentName);
        if (list == null) {
            list = new ArrayList<Issue>();
            map.put(componentName, list);
        }
        list.add(issue);
    }
    return map;
}

好处是：

>您只进行一次地图查找而不是两次.
> list.add()调用在两个地方不重复.

现在,如果你想要考虑一些事情,以下将是一个很好的候选人：

        List<Issue> list = map.get(componentName);
        if (list == null) {
            list = new ArrayList<Issue>();
            map.put(componentName, list);
        }

如果以上出现在多个地方,我肯定会这样做.否则,可能不是(至少不是最初的).

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