如何使用substring（）Java方法正确转换此String？

Question

I have the following problem using the substring() Java function.

I have to do the following operation:

I have a String representing a date having the following form: 2014-12-27 ( YEARS-MONTH-DAY ).

And I want convert it into a String like this: 20141227 (without the space betwen date component).

So I have implemented the following method that use the substring() method to achieve this task:

private String convertDate(String dataPar) {
    String convertedDate = dataPar.substring(0,3) + dataPar.substring(5,6) + dataPar.substring(8,9);
    return  convertedDate;
}

But it don't work well and return to me wrong conversion. Why? What am I missing?

Answer 1

Use replace method which will replace all ocurrences of '-' for '' :

private String convertDate(String dataPar) {
    return dataPar.replace('-', '');
}

Answer 2

Try replaceAll (This ll replace - with "" means it ll remove - ) :

private String convertDate(String dataPar) {
    if(dataPar.length() > 0){
       return dataPar.replaceAll("-","");
    }
    return "NOVAL";
}

Answer 3

A simple way would be to replace all the occurrences of - . If the separator could be different then maybe using SimpleDateFormat would be better.

private String convertDate(String dataPar) {
    return datapar.replaceAll("-", "");
}

Answer 4

如果输入仅是日期，则可以使用SimpleDateFormat并使用类似yyMMdd的格式http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html

Answer 5

I want you to just change the end indeces of the substring() methods as given below

String convertedDate = dataPar.substring(0,4) + dataPar.substring(5,7) + dataPar.substring(8,10);

I tested, It works Fine as you requested :)

Answer 6

private String convertDate(String dataPar) {
    final String year = dataPar.substring(0, 4);
    final String month = dataPar.substring(5, 7);
    final String day = dataPar.substring(8, 10);

    return year + month + day;
}