将Java getTime时间与代表日期的字符串进行比较

Question

I have stored the date of a specific method each time it gets executed in ab sqlite database in 3 columns (one for the day, the month and the year).

Now I want to compare it to the date of the actutal day the user uses the app. With

Date currentTime = Calendar.getInstance().getTime()

I get this date, but how am I able to compare it to the strings I get from my database? Thank you!

Answer 1

Using java.time

Your Question is a duplicate of many others. So briefly…

Use java.time classes rather than the troublesome old legacy date-time classes. For Android, use libraries from the ThreeTen-Backport and ThreeTenABP projects.

Get today's date.

ZoneId z = ZoneId.of( "America/Montreal" ) )
LocalDate today = LocalDate.now( z );

Get to parts of the date.

int y = today.getYear() ;
int m = today.getMonthValue() ;
int d = today.getDayOfMonth() ;

Query the database.

myPreparedStatement.setInt( 1 , y ) ;
myPreparedStatement.setInt( 2 , m ) ;
myPreparedStatement.setInt( 3 , d ) ;

As others suggested, you should be using date-time types in your database to store date-time values rather than mere ints for the pieces.

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About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date , Calendar , & SimpleDateFormat .

The Joda-Time project, now in maintenance mode , advises migration to the java.time classes.

To learn more, see the Oracle Tutorial . And search Stack Overflow for many examples and explanations. Specification is JSR 310 .

Where to obtain the java.time classes?

• Java SE 8 , Java SE 9 , and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport .
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP… .

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval , YearWeek , YearQuarter , and more .

Answer 2

Try this:

SimpleDateFormat formattedDate = new SimpleDateFormat("dd/MM/yyyy");  
String strDate= formattedDate.format(date);  

It will give you your date as shown in the Template. Now simply build a String out of your SQLite data in the same way (dd/MM/yyyy) and you cam simply compare them like shown in this post: https://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java