实施例

Question

我试图在我的应用中显示日期名称和日期以及定义为“文字”的文字显示精细和整数值也显示正常，但它不会显示文字变量，这就是我所拥有的：

Calendar now = Calendar.getInstance();
TextView output3 = (TextView) findViewById(R.id.output3);

int dayno = now.get(Calendar.DAY_OF_WEEK);
String dayName = new String();// also tried String dayName = ""; with the same results
if (dayno == 1) dayName = "Sun";
if (dayno == 1) dayName = "Mon";
if (dayno == 1) dayName = "Tue";
if (dayno == 1) dayName = "Wed";
if (dayno == 1) dayName = "Thu";
if (dayno == 1) dayName = "Fri";
if (dayno == 1) dayName = "Sat";

也尝试过这样：

if (dayno == 1) {dayName = "Sun";}
if (dayno == 1) {dayName = "Mon";}
if (dayno == 1) {dayName = "Tue";}
if (dayno == 1) {dayName = "Wed";}
if (dayno == 1) {dayName = "Thu";}
if (dayno == 1) {dayName = "Fri";}
if (dayno == 1) {dayName = "Sat";}

output3.setText(hour + ":" + minute + ":" + second + " Week " + weekno + ", " + dayName + ", " + yearno);

这是我得到的结果（中间文字字段有错误）

我无法弄清楚这里可能出现什么问题，任何帮助都会受到赞赏

Answer 1

如果条件允许，您的天数相同。正确撰写您的条件。请改用Switch。

Answer 2

请按以下方式更改您的代码：

Calendar now = Calendar.getInstance();
TextView output3 = (TextView) findViewById(R.id.output3);

int dayno = now.get(Calendar.DAY_OF_WEEK);
String dayName = new String();// also tried String dayName = ""; with the same results
if (dayno == 1) dayName = "Sun";
if (dayno == 2) dayName = "Mon";
if (dayno == 3) dayName = "Tue";
if (dayno == 4) dayName = "Wed";
if (dayno == 5) dayName = "Thu";
if (dayno == 6) dayName = "Fri";
if (dayno == 7) dayName = "Sat";

Answer 3

所有if子句检查dayno是否为1。将它们更改为正确的值或使用switch语句，它应该工作正常。对此的switch语句如下所示：

switch(dayno) {
    case Calendar.SUNDAY: 
        dayName = "Sun"; 
        break;
    case Calendar.MONDAY: 
        dayName = "Mon"; 
        break;
    case Calendar.TUESDAY: 
        dayName = "Tue"; 
        break;
    case Calendar.WEDNESDAY: 
        dayName = "Wed"; 
        break;
    case Calendar.THURSDAY: 
        dayName = "Thu"; 
        break;
    case Calendar.FRIDAY:
        dayName = "Fri"; 
        break;
    case Calendar.SATURDAY:
        dayName = "Sat"; 
        break;
}

Answer 4

顺便说一句，您可以使用班级DateFormatSymbols，并避免重新发明轮子

实施例

Calendar now = Calendar.getInstance();

int dayno = now.get(Calendar.DAY_OF_WEEK);
String[] weekdays = new DateFormatSymbols().getWeekdays();
System.out.println(weekdays[dayno]);

，但让我们回到你的问题

你在代码中有这个

if (dayno == 1) dayName = "Sun";

if (dayno == 1) dayName = "Mon";

但如果dayno不是1怎么办？然后 dayName 为空...您有一个复制/粘贴错误

你的意思是肯定的：

if (dayno == 1) {
    dayName = "Sun"
} else if (dayno == 2) {
    dayName = "Mon";
}...

等等

Answer 5

@Leon是对的。你想要这样的东西：

int dayno = now.get(Calendar.DAY_OF_WEEK);
String dayName = new String();

switch(dayno) {
    case 1: dayName = "Sun"; break;
    case 2: dayName = "Mon"; break;
    case 3: dayName = "Tue"; break;
    case 4: dayName = "Wed"; break;
    case 5: dayName = "Thu"; break;
    case 6: dayName = "Fri"; break;
    case 7: dayName = "Sat"; break;
    default: dayName = "dayno is not [1, 7]"; break;
}

假设星期天是1 ...

Answer 6

请勿使用开关或多个if语句，使用SimpleDateFormat

正确打印时间

Calendar now = Calendar.getInstance();
DateFormat df = DateFormat.getDateTimeInstance(); 
// Or... df = new SimpleDateFormat("SOME-TIME-FORMAT");
String nowSting = df.format(now.getTime());
textView.setText(nowString);

我相信你的格式是这样的

hh:mm:ss Week w, EEE, yyyy

Answer 7

使用SWITCH执行此操作。

Calendar now = Calendar.getInstance();
String dayName;
TextView output3 = (TextView) findViewById(R.id.output3);

int dayno = now.get(Calendar.DAY_OF_WEEK);

switch(dayno){
  case 1: dayName = "Sunday"; break;
  case 2: dayName = "Monday"; break;
  case 3: dayName = "Tuesday"; break;
  case 4: dayName = "Wednesday"; break;
  case 5: dayName = "Thursday"; break;
  case 6: dayName = "Friday"; break;
  case 7: dayName = "Saturday"; break;
}

字符串值未在output.setText中显示

7 个答案:

实施例