如何重构其他 - 如果选择正确的构造函数

Question

我在我的应用程序中实现工厂模式的方式，并且工作正常，除了以下代码块（我有另一个，对于另一个类更大）。有没有办法重构这个＆＃34;丛林＆＃34; -structure？提前谢谢！

private Goal createLocalTaskInstance(HashMap<String, Object> goalDetails){
    Goal goal = null;

    if (goalDetails.get("description") == null &&
            goalDetails.get("endDate") == null){
        goal = new Task(String.valueOf(goalDetails.get("title")));

    } else if (goalDetails.get("description") != null &&
            goalDetails.get("endDate") == null) {
        goal = new Task(String.valueOf(goalDetails.get("title")),
                String.valueOf(goalDetails.get("description")));

    } else if (goalDetails.get("description") == null &&
            goalDetails.get("endDate") != null) {
        goal = new Task(String.valueOf(goalDetails.get("title")),
                        (Date) goalDetails.get("endDate"));

    } else if (goalDetails.get("description") != null &&
            goalDetails.get("endDate") != null){
        goal = new Task(String.valueOf(goalDetails.get("title")),
                String.valueOf(goalDetails.get("description")),
                (Date) goalDetails.get("endDate"));
    }
    return goal;
}

Answer 1

我建议您只需调用默认构造函数（包含所有三个参数），无论它们中的某些是否为null，然后只需在构造函数中执行null检查。它看起来像这样：

goal = new Task(String.valueOf(goalDetails.get("title"),
                goalDetails.get("description"), 
                goalDetails.get("endDate"));

任务类：

public class Task {
    private String title;
    private String description;
    private Date endDate;

    public Task(String title, String description, Date endDate) {
        this.title = title;
        if(description != null) {
            this.description = description;
        }
        if(endDate != null) {
            this.endDate = endDate;
        }
    }
}