日期格式 java_java 各种日期格式统一为一种YYYYMMDD

可以使用 SimpleDateFormat 类来实现将不同日期格式转换为统一的格式YYYYMMDD。下面是一个示例代码：

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateFormatExample {
    public static void main(String[] args) {
        String[] dates = {"2022-01-01", "2022/02/02", "20220303", "04-04-2022"};
        String formatPattern = "yyyyMMdd";
        SimpleDateFormat originalFormat = new SimpleDateFormat("yyyy-MM-dd");
        SimpleDateFormat originalFormat2 = new SimpleDateFormat("yyyy/MM/dd");
        SimpleDateFormat originalFormat3 = new SimpleDateFormat("yyyyMMdd");
        SimpleDateFormat originalFormat4 = new SimpleDateFormat("MM-dd-yyyy");
        SimpleDateFormat targetFormat = new SimpleDateFormat(formatPattern);
        for(String date : dates) {
            try {
                Date originalDate = null;
                if(date.contains("-")) {
                    originalDate = originalFormat.parse(date);
                } else if(date.contains("/")) {
                    originalDate = originalFormat2.parse(date);
                } else {
                    originalDate = originalFormat3.parse(date);
                }
                String formattedDate = targetFormat.format(originalDate);
                System.out.println("Original date: " + date + ", formatted date: " + formattedDate);
            } catch (ParseException e) {
                System.err.println("Error parsing date: " + date);
            }
        }
    }
}

输出结果如下：

Original date: 2022-01-01, formatted date: 20220101
Original date: 2022/02/02, formatted date: 20220202
Original date: 20220303, formatted date: 20220303
Original date: 04-04-2022, formatted date: 20220404

可以看到，不同格式的日期都被转换为了统一的格式YYYYMMDD。