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Get previous 30 days starting in java

I am trying to get the previous 30 days of the current date and time .. But, this is not something else

new Date(System.currentTimeMillis() - 30 * 24 * 60 * 60 * 1000)

This returns

Tue Jul 21 04:41:20 IST 2015

Are there any wrong

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3 answers


Never, never, never do anything like this System.currentTimeMillis() - 30 * 24 * 60 * 60 * 100

, there are so many time manipulation rules that this property never works well.

Java 8 Time API

LocalDateTime ldt = LocalDateTime.now().minusDays(30);

What are the outputs 2015-06-01T16:15:54.868

JodaTime

LocalDateTime ldt = new LocalDateTime();
ldt = ldt.minusDays(30);


What are the outputs 2015-06-01T16:18:22.489

The calendar

If you are really desperate

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -30);
Date date = cal.getTime();

What are the outputs Mon Jun 01 16:19:45 EST 2015

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You can use Apache Commons library (commons-lang) .

Date currentDate = new Date();
Date dateBefore30Days = DateUtils.addDays(currentDate, -30);


See this link for more details: http://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/time/DateUtils.html

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The code you provided new Date(System.currentTimeMillis() - 30 * 24 * 60 * 60 * 1000)

may give incorrect results as it does not consider any date / time logic implemented by Java. This will only give a mathematically correct result, not a logically correct result.

You can use the class java.util.Calendar

without using an external library.

Calendar calendar = Calendar.getInstance(); // get Calendar Instance
calendar.add(Calendar.DATE, -30); // add -30 days as you need to subtract 30 days
Date dateRequired = calendar.getTime(); // get the new date from modified cal object.
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