如何使用可重用函数 - Android、Java

Question

当 Calendar instance = Calendar.getInstance(); 时，我实现了小的 if-else 部分来获取月份的前三个字母；检索月份的整数值。我想将它用作可重用的功能。我已经尝试创建另一个 java 文件，但它需要工作。谁能告诉我如何使用它？

public class MstrMonth {

    public MstrMonth() {}

    public static String getCurrentMonth(String currentMonth) {

        Calendar instance = Calendar.getInstance();
        int mMonth = instance.get(Calendar.MONTH) + 1;

        if(mMonth == 1){
            currentMonth = "JAN";
        }else if (mMonth == 2){
            currentMonth = "FEB";
        }else if (mMonth == 3){
            currentMonth = "MAR";
        }else if (mMonth == 4){
            currentMonth = "APR";
        }else if (mMonth == 5){
            currentMonth = "MAY";
        }else if (mMonth == 6){
            currentMonth = "JUN";
        }else if (mMonth == 7){
            currentMonth = "JUL";
        }else if (mMonth == 8){
            currentMonth = "AUG";
        }else if (mMonth == 9){
            currentMonth = "SEP";
        }else if (mMonth == 10){
            currentMonth = "OCT";
        }else if (mMonth == 11){
            currentMonth = "NOV";
        }else if (mMonth == 12){
            currentMonth = "DEC";
        }
        return currentMonth;
    }
}

主要activity;

String currentMonth;
MstrMonth.getCurrentMonth(currentMonth);

我想在这里获取月份代码，但它给出了空值。

Answer 1

试试这个代码，在我的测试项目中工作


public class MstrMonth {

    public MstrMonth() {}

    public static String getCurrentMonth() {

        String currentMonth = null;
        Calendar instance = Calendar.getInstance();
        int mMonth = instance.get(Calendar.MONTH) + 1;

        if(mMonth == 1){
            currentMonth = "JAN";
        }else if (mMonth == 2){
            currentMonth = "FEB";
        }else if (mMonth == 3){
            currentMonth = "MAR";
        }else if (mMonth == 4){
            currentMonth = "APR";
        }else if (mMonth == 5){
            currentMonth = "MAY";
        }else if (mMonth == 6){
            currentMonth = "JUN";
        }else if (mMonth == 7){
            currentMonth = "JUL";
        }else if (mMonth == 8){
            currentMonth = "AUG";
        }else if (mMonth == 9){
            currentMonth = "SEP";
        }else if (mMonth == 10){
            currentMonth = "OCT";
        }else if (mMonth == 11){
            currentMonth = "NOV";
        }else if (mMonth == 12){
            currentMonth = "DEC";
        }
        return currentMonth;
    }
}

在activity


String currentMonth = MstrMonth.getCurrentMonth(currentMonth);

Answer 2

试试这个。

public static String getCurrentMonth() {
    Calendar instance = Calendar.getInstance();
    return instance.getDisplayName(
        Calendar.MONTH, Calendar.SHORT, Locale.ENGLISH).toUpperCase();
}

public static void main(String[] args) throws Exception {
    String currentMonth = getCurrentMonth();
    System.out.println(currentMonth);
}

输出：

NOV

如何使用可重用函数 - Android、Java

How to use reusable function - Android, Java

java

null

coding-style

reusability