Question

我的班级有一个阵列作为其成员之一。在构造函数中，我想将其成员填充到以下内容中。我怎么能这样做，它给了我一个错误。

public class GetCurrentMonth {

    Calendar now;
    String[] monthNames;

    /**
     * 
     */
    public GetCurrentMonth() {
        now = Calendar.getInstance();
        monthNames = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    }

    public String getMonth()
    {
        return monthNames[(now.get(Calendar.MONTH) + 1)];
    }
}

我不想在构造函数中添加这些月份名称，如下所示，因为我想遵循良好的编码习惯，并且我被告知所有初始化都应该在构造函数内完成。

String[] monthNames = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

Answer 1

首先，不仅不是在构造函数中初始化的好习惯，它实际上是坏练习，因为：

你实际上必须编写一个构造函数（添加无用的代码）
字段应为static final，如果它们对于每个实例都相同，例如月份
实例字段应尽可能final并在声明时初始化，如果只有一种方法可以初始化它们

最佳做法，包括遵守命名标准，表示您的课程应如下所示：

public class GetCurrentMonth {
    private static final String[] MONTH_NAMES = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
    private final Calendar now = Calendar.getInstance();

    public String getMonth() {
        return MONTH_NAMES [(now.get(Calendar.MONTH) + 1)];
    }
}

Answer 2

您需要使用新的String []

创建数组

monthNames = new String[] {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

Answer 3

首先，我同意Bohemian♦的答案，但我甚至会更进一步，建议您创建一个包含月份名称的Enum。我将如何做到这一点：

public enum Month {
    JANUARY("January"), 
    FEBRUARY("February"), 
    MARCH("March"), 
    APRIL("April"), 
    MAY("May"),
    JUNE("June"), 
    JYLY("July"), 
    AUGUST("August"), 
    SEPTEMBER("September"),
    OCTOBER("October"), 
    NOVEMBER("November"), 
    DECEMBER("December");

    private String displayName;

    private Month(String displayName) {
        this.displayName = displayName;
    }

    @Override
    public String toString() {
        return displayName;
    }

    public static Month valueOfIgnoreCase(String value) {
        return valueOf(value.toUpperCase());
    }
}

声明后填充数组成员

3 个答案: