Check Whether Time Interval has Passed:

}}

before()
equals()
also work with same syntax as after()

Various get and set methods:

get methods

Date currentTime = new Date();int hours = currentTime.getHours(); // hours passed since midnight. 

int mins = currentTime.getMinutes(); // hours passed since midnight.int secs = currentTime.getSeconds(); // seconds passed since midnight.

set methods

Date yearStartTime = new Date(); 

yearStartTime.setHours(0); 

yearStartTime.setMinutes(0); 

yearStartTime.setSeconds(0); 

yearStartTime.setDate(1); // First day of month

yearStartTime.setMonth(0); // January (months are indexed from 0 to 11)

Calendar class:

Calendar calendar = new GregorianCalendar(2017, 0 , 25);

GregorianCalendar calendar = new GregorianCalendar(2017, Calendar.JANUARY , 25);

set the time 10:30:15 1 Jan 2019

public static void main(String[] args) { Calendar calendar = new GregorianCalendar(); calendar.set(Calendar.YEAR, 2019); calendar.set(Calendar.MONTH, 0); calendar.set(Calendar.DAY_OF_MONTH, 1); calendar.set(Calendar.HOUR_OF_DAY, 10); calendar.set(Calendar.MINUTE, 30); calendar.set(Calendar.SECOND, 15); System.out.println(calendar.getTime());}

Output:

Tue Jan 01 10:30:15 IST 2019
—————————————————————-

public static void main(String[] args) { Calendar calendar = new GregorianCalendar(2019, Calendar.JANUARY , 1); calendar.set(Calendar.HOUR, 10); calendar.set(Calendar.MINUTE, 30); calendar.set(Calendar.SECOND, 15); calendar.add(Calendar.MONTH, –2); // Date will automatically adjust into 2018. System.out.println(calendar.getTime());}

output:
Thu Nov 01 10:30:15 IST 2018
——————————————————————
roll() : This method will make change only in particular part, In this example
only Month will be reduced to Nov but years and other time will not be changed.

public static void main(String[] args) { Calendar calendar = new GregorianCalendar(2019, Calendar.JANUARY , 1); calendar.set(Calendar.HOUR, 10); calendar.set(Calendar.MINUTE, 30); calendar.set(Calendar.SECOND, 15); calendar.roll(Calendar.MONTH, –2); // Date will automatically adjust into 2018. System.out.println(calendar.getTime());}
Output:
Fri Nov 01 10:30:15 IST 2019
——————————————————————

get and set:

calendar.set(Calendar.HOUR, 10);calendar.set(Calendar.MINUTE, 30);calendar.set(Calendar.SECOND, 15); System.out.println(“Year: “ + calendar.get(Calendar.YEAR));System.out.println(“Month: “ + calendar.get(Calendar.MONTH));
——————————————————————-

date format:

SimpleDateFormat dateFormat = new SimpleDateFormat(“EEEE, MMMM d, yyyy”);
Calendar calendar = new GregorianCalendar(2019, Calendar.JANUARY , 1);
System.out.println(dateFormat.format(calendar.getTime()));

output:
Tuesday, January 1, 2019

Difference of days between two dates:

Traversing Collection Syntax:

Collection Methods:

ArrayList<Integer> list = new ArrayList<Integer>();

sort() : Collection.sort(list);
max() : Collection.max(list);
min() : Collection.min(list);
reverse() : Collection.reverse(list);
shuffle() : Collection.shuffle(list);
swap() : Collection.swap(list, i, j);


unmodifiableList() : creates immutable arrayList from an array.
List<String> weekEndDays = Collections.unmodifiableList(new ArrayList<>(Arrays.asList(saturday, sunday)));

disjoint() : It checks whether two collections intersect, returns false if intersection is non null otherwise true.

ArrayList<String> list1 = new ArrayList<>(Arrays.asList(sunday, monday, tuesday));ArrayList<String> list2 = new ArrayList<>(Arrays.asList(saturday, sunday));
Collection.disjoint(list1, list2); // will return false, sunday is common.

Collection Initialization: