java get the first date and last date of given month and given year

java.time.YearMonth methods atDay & atEndOfMonth

The java.time framework built into Java 8+ (Tutorial) has commands for this.

The aptly-named YearMonth class represents a month of a year, without any specific day or time. From there we can ask for the first and days of the month.

YearMonth yearMonth = YearMonth.of( 2015, 1 );     // 2015-01. January of 2015.
LocalDate firstOfMonth = yearMonth.atDay( 1 );     // 2015-01-01
LocalDate lastOfMonth = yearMonth.atEndOfMonth();  // 2015-01-31

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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.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, 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
• Later versions of Android bundle implementations of the java.time classes.
• For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). 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.

Simply you can use Calendar class. you should assign month variable which month you want

        Calendar gc = new GregorianCalendar();
        gc.set(Calendar.MONTH, month);
        gc.set(Calendar.DAY_OF_MONTH, 1);
        Date monthStart = gc.getTime();
        gc.add(Calendar.MONTH, 1);
        gc.add(Calendar.DAY_OF_MONTH, -1);
        Date monthEnd = gc.getTime();
        SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");

        System.out.println("Calculated month start date : " + format.format(monthStart));
        System.out.println("Calculated month end date : " + format.format(monthEnd));

First day:

Calendar.getInstance().getActualMinimum(Calendar.DAY_OF_MONTH);

Last day of month:

Calendar.getInstance().getActualMaximum(Calendar.DAY_OF_MONTH);