如何使用LocalDate获得正确的日期格式

Question

谢谢你！

    String yearParsed = String.valueOf(year);
    String monthParsed;
    String dayParsed;
    if (dayString.length() == 1) {         
        dayParsed = "0" + String.valueOf(day); 
    }
    else {
        dayParsed = String.valueOf(day);
    }
    if (monthString.length() == 1) {         
        monthParsed = "0" + String.valueOf(month);        
    }
    else {
        monthParsed = String.valueOf(month);
    }
    
    String dateString = yearParsed + "-" + monthParsed + "-" + dayParsed;
    //String dateString = dayParsed + "-" + monthParsed + "-" + yearParsed;

    System.out.println("dateString " + dateString);
    
    LocalDate formattedDate = null;  
    DateTimeFormatter dateTimeFormatter;  
    dateTimeFormatter = DateTimeFormatter.ISO_LOCAL_DATE;
    //dateTimeFormatter = DateTimeFormatter.ofPattern("dd-MM-YYYY");

    formattedDate = formattedDate.parse(String.format(dateString, dateTimeFormatter));
    System.out.println("Formatted Date = " + formattedDate);

Answer 1

关于变量localdateformatteddate，您误解了格式化日期的概念。

格式化日期是一个字符串，因为您可以控制它的格式。

当对象是localdate实例时，它包含确定时间中位置的值，当您只是打印它时，它有其默认格式，如果您想要一个特定格式，您需要一个日期的字符串表示

String year = "2021", dayString = "1", monthString = "3";

LocalDate date = LocalDate.of(
        Integer.parseInt(year),
        Integer.parseInt(monthString),
        Integer.parseInt(dayString)
);

System.out.println(date); // 2021-03-01

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd-MM-yyyy");
String formattedDate = date.format(dtf);
System.out.println("Formatted Date = " + formattedDate); // Formatted Date = 01-03-2021