使用字符串将日期从数字格式转换/替换为EEEE、MMMMDD、yyyy格式

Question

// format output EEEE, MM dd yyyy 
SimpleDateFormat write      = new SimpleDateFormat("EEEE, MMMM dd, yyyy");
SimpleDateFormat read       = new SimpleDateFormat("MM/dd/yyyy");
SimpleDateFormat readYy     = new SimpleDateFormat("MM/dd/yy");
SimpleDateFormat writeYyyy  = new SimpleDateFormat("MM/dd/yyyy");

// dates used for a test conversion     
String[] dates = {
"7/20/1969","7/4/2012",
"9/11/01",      // this should be 2001 (m/d/yyyy = 8 chars, mm/dd/yy = 8 chars
"02/29/1975", "6/11/1956", "31/31/00", "7/&&/88" }

现在我一直在试图找到一个应该可行的解决办法，但由于某种原因，它并不奏效。请参阅下一段代码：

String line = "We landed on the moon on 7/20/1969. 7/4/2012 is the Fourth of July.";

// I expect to see "7/20/1969" and "7/20/2012" as output but the following does not
// work:

dateRegex = "^([1-9]|0[1-9]|1[012])/([1-9]|0[1-9]|[1-2][0-9]|3[01])/(\\d\\d)|(19|20)\\d\\d$";
Pattern p = Pattern.compile(dateRegex);
Matcher m = p.matcher(line);
System.out.println(line);

while(m.find()) {
    System.out.println("Found " + p + " at: " + m.start());
    // return the sequences characters matching "dateRegex (or so it should...?)
    System.out.println("Match : " + m.group())  // it does not print 'cause nothing is found
}
// the above code works find with a simpler regex string variable, but nothing like this
// what's worng here?   Is this a wrong "dateRegex" pattern?  Thanks.

我会很感激任何能证明结果的帮助。多谢了。

Answer 1

是否使用String.Format（）？

String.format("On %s, a really cool thing happened.", DateTimeFormatter.print()DateTime.now());

当然，这个例子使用了卓越得多的Joda时间库。你也该这么做。

更新：在正确理解问题之后（我认为），这个小示例，使用标准Java库应该可以让您开始。

package com.company;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.regex.Pattern;

public class Main {

    public static void main(String[] args) {
        String example = "On 9/6/78, a really cool thing happened...";
        SimpleDateFormat replacement = new SimpleDateFormat("EEEE, MMMM dd, yyyy");
        Pattern datePattern = Pattern.compile("\\b\\w{1,2}/\\w{1,2}/(?:\\w{4}|\\w{2})\\b");
        Date now = new Date();
        System.out.println(datePattern.matcher(example).replaceAll(replacement.format(now)));
    }
}