We Keep Coding

Formatting time in Android Application

I've created an Android grading app to use within my classes. All the database connections and grading logic has been laid out and functions precisely as it should.
However, I am having a problem incorporating the Java Calendar class. I need to be able to limit each class to submit their answers "only" during their class time. As you can see, I will need to incorporate a series of "if statements" in order to do this.
The problem is that I don't know how to get this time that I need to verify that my student's answer submissions are only handled during their class time.
This is what I've tried:
Calendar cal = Calendar.getInstance();
int hour = cal.get(Calendar.HOUR);
int minute = cal.get(Calendar.MINUTE);
As you can see, I am only able to get hours and minutes separate from each other. How do I get the real time? Just Hours and minutes not seconds.
In my code my set up should look like this:
int period = will be selected from a spinner object
if(period == 1 && (time>= 7:20 AM && time<= 9:00AM)) Then, go ahead and
submit your answers to online database.
if(period == 8 && (time>= 12:50PM && time<= 2:20PM)) Then, go ahead and
submit your answers to online database.
I don't know how to format this "time" object with the Calendar class.
Any help would be appreciated.

You can set hours and minutes to the calendar:
Calendar start = Calendar.getInstance();
start.set(Calendar.HOUR, 7);
start.set(Calendar.MINUTE, 20);
The same for the endDate:
Calendar end = Calendar.getInstance();
end.set(Calendar.HOUR, 9);
end.set(Calendar.MINUTE, 0);
To check that the current datetime is in the interval:
Calendar cal = Calendar.getInstance();//now
boolean isInInterval = cal.getTime().after(start.getTime()) && cal.getTime().before(end.getTime());

How to check if Current Hour falls between certain range

I am trying to check if Current Hour falls in between 7AM and 10AM
I am doing it this way
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
int hour = cal.get(Calendar.HOUR_OF_DAY);
if(hour >= 7 && hour <= 10)
{
}
Please tell me if this is a valid approach to follow

Yes that is a valid approach. You could also use the new Time API (needs Java 8)
import java.time.LocalTime;
...
int hour = LocalTime.now().getHour();
It's a bit shorter to get the hour. There is also an overloaded now(ZoneId zoneId) method.
Or make it a one liner with a temporal query (also needs Java 8):
Boolean isBetween7and10AM = LocalTime.now().query(date -> date.get(ChronoField.CLOCK_HOUR_OF_DAY) >=7 &&
date.get(ChronoField.CLOCK_HOUR_OF_DAY) < 10);

Yup. This looks fine. Remember that this Calendar field is dependent on the timezone.
BTW: Put the starting curly brace at the end of the previous line, since this is the common code formatting style.
:-)

Knowing if time has passed in java

I would like to know if the current time has passed 12 pm already. Can I do it in an if statement like:
if(timenow is already pass 12 pm){
**do code here**
}
Is there a java code or a method in joda time that can do that? All answers are appreciated. Thanks. :)

Calendar cal = Calendar.getInstance();
if (cal.get(Calendar.HOUR_OF_DAY) >= 12) {
...
}

JAVA
int hour = LocalDateTime.now().getHour();
JODATIME
DateTime dt = new DateTime(); // current time
int hour = dt.getHourOfDay(); // gets hour of day
and put the logic here
if(hour >= 12){
do code here
}

Check if DAY_OF_WEEK is between Monday and Friday

I'm trying to create a method which is checking if "today" is between Monday and Friday. For this I get with this line 'int day = Calendar.DAY_OF_WEEK;' the actual day. After that I fill a ArrayList with the days (Monday, Tuesday, Wendsday, Thursday and Friday). Now when I check if the actual day is in my ArrayList, i set boolean DAY = true else i set boolean DAY = false. I tryed the Method today and yesterday, but it allways sets the boolean to false.
What do I need to change that my code works? You'll find the code down here.
Code
int day = Calendar.DAY_OF_WEEK;
ArrayList<Integer> daylist = new ArrayList<Integer>();
daylist.add(Calendar.MONDAY);
daylist.add(Calendar.TUESDAY);
daylist.add(Calendar.WEDNESDAY);
daylist.add(Calendar.THURSDAY);
daylist.add(Calendar.FRIDAY);
if (daylist.contains(day)){
DAY = true;
}else{
DAY = false;
}

Wow, that's like trying to kill a mosquito with a thermo-nuclear warhead :-)
Java guarantees (in 1.5) (unchanged up to 1.8 at least) that the values of SUNDAY through SATURDAY are contiguous (1 through 7) so it's a simple matter of checking a range.
However, DAY_OF_WEEK is not the day of the week, it's a field number (with the value 7) to be passed to the getter to retrieve the day of the week. The only time Calendar.DAY_OF_WEEK itself will match an actual day will be on Saturdays.
You can use code such as:
Calendar myDate = Calendar.getInstance(); // set this up however you need it.
int dow = myDate.get (Calendar.DAY_OF_WEEK);
boolean isWeekday = ((dow >= Calendar.MONDAY) && (dow <= Calendar.FRIDAY));
Following this, isWeekday will be true if and only if the day from myDate was Monday through Friday inclusive.

int day = Calendar.DAY_OF_WEEK; should instead be
Calendar cal; // The calendar object
....your other code for getting the date goes here....
int day = cal.get(Calendar.DAY_OF_WEEK);
Your current code just gets the value of the constant Calendar.DAY_OF_WEEK.

This should do the trick for you i assume.
int day = cal.get(Calendar.DAY_OF_WEEK);
if (day >= Calendar.MONDAY && day <= Calendar.FRIDAY){
DAY = true;
}else{
DAY = false;
}

int day = Calendar.DAY_OF_WEEK;
The logic is broken right here. DAY_OF_WEEK is a constant identifying which type of data we need to retrieve from a Calendar instance.
The simplest solution to your problem (since Calendar.FRIDAY > ... > Calendar.MONDAY) is
Calendar now = Calendar.getInstance();
int day = now.get(Calendar.DAY_OF_WEEK);
if (day >= Calendar.MONDAY && day <= Calendar.FRIDAY)
// do something

First Calendar.DAY_OF_WEEK is an integer field will always gives you 7. You need to create an instance of a Calendar like Calendar cal = Calendar.getInstance(); By default it gives you the current date in current timezone.
Then you can call cal.get(Calendar.DAY_OF_WEEK); which will give you any day between Sunday and Sat'day
Now you can check something like this
if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY || cal.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY) {
System.out.println("Weekend");
} else {
System.out.println("Weekday");
}
You can apply this logic to your problem!!

Java Date & Time of Day

I have an application that passes in java.util.Date. I want to check whether this date is within a specified time of day (e.g. between 10:30 & 11:30), I don't care about the date, just the time of day.
Can anyone show me a simple way to do this?
Thanks

This is what the Calendar class is for. Assuming date is your Date object:
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int hour = cal.get(Calendar.HOUR_OF_DAY);
int minutes = cal.get(Calendar.MINUTE);
if (hour == 10 && minutes >= 30 || hour == 11 && minutes <= 30) {
...
}