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To find number of days b/w two dates there is logcat error of SimpledateFormat [duplicate]

This question already has answers here:
Android/Java - Date Difference in days
(18 answers)
Closed 6 years ago.
i want to find total number of days b/w "from date" to "To date". Thanks in advance
here is my complete code
public class Main2Activity extends AppCompatActivity {
EditText ed1,ed2,ed4,ed5,ed6;Button b1; int day_x;int month_x;int year_x;int DIALOG_ID = 1;
#Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main2); AlertDialog.Builder a_builder = new AlertDialog.Builder(Main2Activity.this);a_builder.setMessage("Please Enter your\n'Name' and 'Date of Birth'.").setCancelable(false).setTitle("Alert!!!").setNegativeButton("ok", new DialogInterface.OnClickListener() { #Override public void onClick(DialogInterface dialogInterface, int i) { dialogInterface.cancel(); }}).show();date_selector(); to_date();final Calendar cal = Calendar.getInstance(); year_x = cal.get(Calendar.YEAR); month_x = cal.get(Calendar.MONTH); day_x = cal.get(Calendar.DAY_OF_MONTH); } public void date_selector() {ed2 = (EditText) findViewById(R.id.editText2); ed5 = (EditText) findViewById(R.id.editText5);ed4 = (EditText) findViewById(R.id.editText4);ed6 = (EditText) findViewById(R.id.editText6);ed1 = (EditText) findViewById(R.id.editText1);ed2.setOnClickListener( new View.OnClickListener() { #Override public void onClick(View view) {showDialog(DIALOG_ID);
}
}
);
}
#Override
protected Dialog onCreateDialog(int ids) {
if (ids == DIALOG_ID)
return new DatePickerDialog(Main2Activity.this, dickerListener, year_x, month_x, day_x);
return null;
}
private DatePickerDialog.OnDateSetListener dickerListener =
new DatePickerDialog.OnDateSetListener() {
public long dateEvent;
#Override
public void onDateSet(DatePicker datePicker, int i, int i1, int i2) {
year_x = i;
month_x = i1+1 ;
day_x = i2;
ed2.setText((day_x+"/"+month_x+"/"+year_x));//showing DOB
//String stores=ed2.getText().toString();
final Calendar cal = Calendar.getInstance();
int year_y = cal.get(Calendar.YEAR);
int month_y = cal.get(Calendar.MONTH);
int day_y = cal.get(Calendar.DAY_OF_MONTH);
int month_z=month_y+1;
// SimpleDateFormat df = new SimpleDateFormat("dd mm yyyy");
ed5.setText(day_y+"/"+ month_z+"/"+ year_y);
String value = ed2.getText().toString();
ed4.setText(value);
Daysss_check();
}
};
public void Daysss_check() { //total number of days???
ed5 = (EditText) findViewById(R.id.editText5);
ed4 = (EditText) findViewById(R.id.editText4);
ed6 = (EditText) findViewById(R.id.editText6);
ed2 = (EditText) findViewById(R.id.editText2);
SimpleDateFormat df = new SimpleDateFormat("dd/MM/yyyy");
String firstDate = ed2.getText().toString();
String secondDate = ed5.getText().toString();
try {
Date date1 = df.parse(firstDate);
Date date2 = df.parse(secondDate);
long diff = date2.getTime() - date1.getTime();
long diffDays= TimeUnit.DAYS.convert(diff, TimeUnit.MILLISECONDS);
// float dayCount = (float) diff / (24 * 60 * 60 * 1000);
//String.valueOf((int) dayCount);
String myDaycount = String.valueOf(diffDays);
ed6.setText(myDaycount);
} catch (ParseException e) {
e.printStackTrace();
}
}
this is the output of my app and i want to find total number of days b/w "from date" to "To date". Thanks in advance

long diff = date1.getTime() - date2.getTime();
long seconds = diff / 1000;
long minutes = seconds / 60;
long hours = minutes / 60;
long days = hours / 24;
please try this. Hope it helps you

Getting time in Millis since UNIX epoch from a CalendarView

I want find the seconds between the current time and a date selected from a a calendar view. My current method goes as follows
mCalculateButton = (Button) findViewById(R.id.calcButton);
mDatePicker = (CalendarView) findViewById(R.id.calendarView);
mCalculateButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//Grabbing the date selected from the CalendarView to send to intent
long age = mDatePicker.getDate();
startCalculation(age);
}
});
}
private void startCalculation(long age){
Intent intent = new Intent(this, CalcActivity.class);
intent.putExtra("key_age", age);
startActivity(intent);
}
and in the calculations activity
Intent intent = getIntent();
//Date selected in MSUE
mSelectedTime = intent.getLongExtra("key_age", 0);
//Current date in MSUE
mCurrTime = System.currentTimeMillis();
mSecondsInfo = (TextView) findViewById(R.id.secondsInfo);
mDaysInfo = (TextView) findViewById(R.id.daysInfo);
mMonthsInfo = (TextView) findViewById(R.id.monthsInfo);
mYearsInfo = (TextView) findViewById(R.id.yearsInfo);
//Replacing format specifiers with desired age information
mSecondsInfo.setText(mSecondsInfo.getText().toString().replace("%i%", Long.toString(ageInSeconds(mSelectedTime, mCurrTime))));
mDaysInfo.setText(mDaysInfo.getText().toString().replace("%i%", Long.toString(ageInDays(mSelectedTime, mCurrTime))));
mMonthsInfo.setText(mMonthsInfo.getText().toString().replace("%i%", Long.toString(ageInMonths(mSelectedTime, mCurrTime))));
mYearsInfo.setText(mYearsInfo.getText().toString().replace("%i%", Long.toString(ageInYears(mSelectedTime, mCurrTime))));
}
private long ageInSeconds(long mil, long currTime){
return (currTime - mil) / 1000;
}
private long ageInDays(long mil, long currTime){
return (currTime - mil)/ 1000 / 60 / 60 / 24;
}
private long ageInMonths(long mil, long currTime){
return (currTime - mil) / 1000 / 60 / 60 / 24/ 30;
}
private long ageInYears(long mil, long currTime){
return (currTime - mil) / 1000 / 60 / 60 / 24/ 30 / 12;
}
The issue is that the time returned by mDatePicker.getDate only increases by ~4000 milliseconds each day that it increments and I have no idea why. Any ideas as of to why this does not work?

CalendarView is not storing the selected date, but you can listen to the selection event and store it yourself.
mDatePicker .setOnDateChangeListener(new CalendarView.OnDateChangeListener() {
#Override
public void onSelectedDayChange(CalendarView view, int year, int month, int dayOfMonth) {
storedDate = new GregorianCalendar(year,month,dayOfMonth);
}
});
mCalculateButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startCalculation(storedDate.getTimeInMillis());
}
});

SimpleDateFormat and wrong dates

I had already tried the first two suggestions below, but I tried again and sincerely thanks for the help! The result is the same though. I´ll just edit the post to add more code info.
Hello there! I´m experimenting with a simple ToDo application and managed to change almost everything I wanted besides the date formatted that´s displayed once the user saves the task.
The task itself is added via the AddToDoActivity class which has the following resumed code:
public class AddToDoActivity extends Activity {
// 7 days in milliseconds - 7 * 24 * 60 * 60 * 1000
private static final int SEVEN_DAYS = 604800000;
private static final String TAG = "Lab-UserInterface";
private static String timeString;
private static String dateString;
private static TextView dateView;
private static TextView timeView;
private Date mDate;
private RadioGroup mPriorityRadioGroup;
private RadioGroup mStatusRadioGroup;
private EditText mTitleText;
private RadioButton mDefaultStatusButton;
private RadioButton mDefaultPriorityButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_todo);
mTitleText = (EditText) findViewById(R.id.title);
mDefaultStatusButton = (RadioButton) findViewById(R.id.statusNotDone);
mDefaultPriorityButton = (RadioButton) findViewById(R.id.medPriority);
mPriorityRadioGroup = (RadioGroup) findViewById(R.id.priorityGroup);
mStatusRadioGroup = (RadioGroup) findViewById(R.id.statusGroup);
dateView = (TextView) findViewById(R.id.date);
timeView = (TextView) findViewById(R.id.time);
// Set the default date and time
setDefaultDateTime();
// OnClickListener for the Date button, calls showDatePickerDialog() to show
// the Date dialog
final Button datePickerButton = (Button) findViewById(R.id.date_picker_button);
datePickerButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
showDatePickerDialog();
}
});
// OnClickListener for the Time button, calls showTimePickerDialog() to show
// the Time Dialog
final Button timePickerButton = (Button) findViewById(R.id.time_picker_button);
timePickerButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
showTimePickerDialog();
}
});
// OnClickListener for the Cancel Button,
final Button cancelButton = (Button) findViewById(R.id.cancelButton);
cancelButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
log("Entered cancelButton.OnClickListener.onClick()");
finish();
}
});
//OnClickListener for the Reset Button
final Button resetButton = (Button) findViewById(R.id.resetButton);
resetButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
log("Entered resetButton.OnClickListener.onClick()");
setDefaultDateTime();
mTitleText.setText("");
mDefaultStatusButton.setChecked(true);
mDefaultPriorityButton.setChecked(true);
}
});
// OnClickListener for the Submit Button
// Implement onClick().
final Button submitButton = (Button) findViewById(R.id.submitButton);
submitButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
log("Entered submitButton.OnClickListener.onClick()");
// Gather ToDoItem data
Priority priority = getPriority();
Status status = getStatus();
String titleString = mTitleText.getText().toString();
// Date
String fullDate = dateString + " " + timeString;
// Package ToDoItem data into an Intent
Intent data = new Intent();
ToDoItem.packageIntent(data, titleString, priority, status, fullDate);
setResult(Activity.RESULT_OK, data);
finish();
}
});
}
// Do not modify below here
// Use this method to set the default date and time
private void setDefaultDateTime() {
// Default is current time + 7 days
mDate = new Date();
mDate = new Date(mDate.getTime() + SEVEN_DAYS);
Calendar c = Calendar.getInstance();
c.setTime(mDate);
setDateString(c.get(Calendar.DAY_OF_MONTH), c.get(Calendar.MONTH),
c.get(Calendar.YEAR));
dateView.setText(dateString);
setTimeString(c.get(Calendar.HOUR_OF_DAY), c.get(Calendar.MINUTE),
c.get(Calendar.MILLISECOND));
timeView.setText(timeString);
}
private static void setDateString(int dayOfMonth, int monthOfYear, int year) {
// Increment monthOfYear for Calendar/Date -> Time Format setting
monthOfYear++;
String mon = "" + monthOfYear;
String day = "" + dayOfMonth;
if (monthOfYear < 10)
mon = "0" + monthOfYear;
if (dayOfMonth < 10)
day = "0" + dayOfMonth;
dateString = year + "-" + mon + "-" + day;
}
private static void setTimeString(int hourOfDay, int minute, int mili) {
String hour = "" + hourOfDay;
String min = "" + minute;
if (hourOfDay < 10)
hour = "0" + hourOfDay;
if (minute < 10)
min = "0" + minute;
timeString = hour + ":" + min + ":00";
}
private Priority getPriority() {
switch (mPriorityRadioGroup.getCheckedRadioButtonId()) {
case R.id.lowPriority: {
return Priority.LOW;
}
case R.id.highPriority: {
return Priority.HIGH;
}
default: {
return Priority.MED;
}
}
}
private Status getStatus() {
switch (mStatusRadioGroup.getCheckedRadioButtonId()) {
case R.id.statusDone: {
return Status.DONE;
}
default: {
return Status.NOTDONE;
}
}
}
// DialogFragment used to pick a ToDoItem deadline date
public static class DatePickerFragment extends DialogFragment implements
DatePickerDialog.OnDateSetListener {
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Use the current date as the default date in the picker
final Calendar c = Calendar.getInstance();
int day = c.get(Calendar.DAY_OF_MONTH);
int month = c.get(Calendar.MONTH);
int year = c.get(Calendar.YEAR);
// Create a new instance of DatePickerDialog and return it
return new DatePickerDialog(getActivity(), this, year, month, day);
}
#Override
public void onDateSet(DatePicker view, int dayOfMonth, int monthOfYear,
int year) {
setDateString(dayOfMonth, monthOfYear, year);
dateView.setText(dateString);
}
}
// DialogFragment used to pick a ToDoItem deadline time
public static class TimePickerFragment extends DialogFragment implements
TimePickerDialog.OnTimeSetListener {
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
// Use the current time as the default values for the picker
final Calendar c = Calendar.getInstance();
int hour = c.get(Calendar.HOUR_OF_DAY);
int minute = c.get(Calendar.MINUTE);
// Create a new instance of TimePickerDialog and return
return new TimePickerDialog(getActivity(), this, hour, minute,
true);
}
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
setTimeString(hourOfDay, minute, 0);
timeView.setText(timeString);
}
}
private void showDatePickerDialog() {
DialogFragment newFragment = new DatePickerFragment();
newFragment.show(getFragmentManager(), "datePicker");
}
private void showTimePickerDialog() {
DialogFragment newFragment = new TimePickerFragment();
newFragment.show(getFragmentManager(), "timePicker");
}
private void log(String msg) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i(TAG, msg);
}
}
Here´s the ToDoItem, that actually reads the info from AddToDoActivity:
public class ToDoItem {
public static final String ITEM_SEP = System.getProperty("line.separator");
public enum Priority {
LOW, MED, HIGH
};
public enum Status {
NOTDONE, DONE
};
public final static String TITLE = "title";
public final static String PRIORITY = "priority";
public final static String STATUS = "status";
public final static String DATE = "date";
public final static String FILENAME = "filename";
public final static SimpleDateFormat FORMAT = new SimpleDateFormat(
"dd/MM/yyyy HH:mm:ss", Locale.US);
private String mTitle = new String();
private Priority mPriority = Priority.LOW;
private Status mStatus = Status.NOTDONE;
private Date mDate = new Date();
ToDoItem(String title, Priority priority, Status status, Date date) {
this.mTitle = title;
this.mPriority = priority;
this.mStatus = status;
this.mDate = date;
}
// Create a new ToDoItem from data packaged in an Intent
ToDoItem(Intent intent) {
mTitle = intent.getStringExtra(ToDoItem.TITLE);
mPriority = Priority.valueOf(intent.getStringExtra(ToDoItem.PRIORITY));
mStatus = Status.valueOf(intent.getStringExtra(ToDoItem.STATUS));
try {
mDate = ToDoItem.FORMAT.parse(intent.getStringExtra(ToDoItem.DATE));
} catch (ParseException e) {
mDate = new Date();
}
}
public String getTitle() {
return mTitle;
}
public void setTitle(String title) {
mTitle = title;
}
public Priority getPriority() {
return mPriority;
}
public void setPriority(Priority priority) {
mPriority = priority;
}
public Status getStatus() {
return mStatus;
}
public void setStatus(Status status) {
mStatus = status;
}
public Date getDate() {
return mDate;
}
public void setDate(Date date) {
mDate = date;
}
// Take a set of String data values and
// package them for transport in an Intent
public static void packageIntent(Intent intent, String title,
Priority priority, Status status, String date) {
intent.putExtra(ToDoItem.TITLE, title);
intent.putExtra(ToDoItem.PRIORITY, priority.toString());
intent.putExtra(ToDoItem.STATUS, status.toString());
intent.putExtra(ToDoItem.DATE, date);
}
public String toString() {
return mTitle + ITEM_SEP + mPriority + ITEM_SEP + mStatus + ITEM_SEP
+ FORMAT.format(mDate);
}
public String toLog() {
return "Title:" + mTitle + ITEM_SEP + "Priority:" + mPriority
+ ITEM_SEP + "Status:" + mStatus + ITEM_SEP + "Date:"
+ FORMAT.format(mDate);
}
}
Oh well, after hours tweaking the
public final static SimpleDateFormat FORMAT = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss", Locale.US);
method from ToDoItem, I still cannot successfully convert yyyy-MM-dd to dd/MM/yyyy.
First, I´ve tried the obvious, and changed the expression yyyy-MM-dd to dd/MM/yyyy.
After that, all I got after saving the task was today´s date, even though the date inputted on AddToDoActivity is months or years ahead. If I revert back to yyyy-MM-dd, the date shown on the Task List is the same inputted on AddToDoActivity.
Then I tried to change all mentions of dates on every class to match the exact format that I wanted.
That made everything look good on AddToDoActivity, but again, when I transported the date back to ToDoItem, the app just ignored the previously inputted date and showed today´s date again.
Can anyone help me with this one??
Thanks!!

You are calling setDateString with arguments in the order of year, month, day:
setDateString(c.get(Calendar.YEAR), c.get(Calendar.MONTH),
c.get(Calendar.DAY_OF_MONTH));
But your method has parameters in the order of day, month, year:
private static void setDateString(int dayOfMonth, int monthOfYear, int year) {
...
}
I also think you made some errors while copying your code into the question, since the setDateString method is duplicated and there is no setTimeString method.

Change:
setDateString(c.get(Calendar.YEAR), c.get(Calendar.MONTH), c.get(Calendar.DAY_OF_MONTH));
to:
setDateString(c.get(Calendar.DAY_OF_MONTH), c.get(Calendar.MONTH), c.get(Calendar.YEAR));

Modify the code as follows in the ToDoListAdapter file getView method
// TODO - Display Time and Date.
// Hint - use ToDoItem.FORMAT.format(toDoItem.getDate()) to get date and time String
final TextView dateView = (TextView) itemLayout.findViewById(R.id.dateView);
dateView.setText(ToDoItem.FORMAT.format(toDoItem.getDate()));
The output will be something similar the the following
Reference:
Completing UI Activity assignment

how to update edittext on datepicker set button [duplicate]

This question already exists:
edittext not updated when set new date
Closed 9 years ago.
this is my code which work fine updare edittext but problem is edittext not update imediately until i click again on edittext tell me how do i update edittext on datepicker dailog (positive button) h date picker display two default button positive and negative how do i update editteext on positive button help me please
EditText edtKeyword;
String selectedDate;
int mYear,mMonth,mDay ;
DateFormat fmtDateAndTime = DateFormat.getDateInstance();
Calendar myCalendar = Calendar.getInstance();
DatePickerDialog.OnDateSetListener d = new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
myCalendar.set(Calendar.YEAR, year);
myCalendar.set(Calendar.MONTH, monthOfYear);
myCalendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
edtKeyword = (EditText) findViewById(R.id.edtKeyword);
edtKeyword.setClickable(true);
edtKeyword.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new DatePickerDialog(MenuList.this, d, myCalendar
.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH)).show();
mYear = myCalendar.get(Calendar.YEAR);
mMonth = myCalendar.get(Calendar.MONTH);
mDay = myCalendar.get(Calendar.DAY_OF_MONTH);
selectedDate= mMonth+"-"+mDay+"-"+mYear;
edtKeyword.setText(selectedDate);
}
});
edtKeyword.setText(fmtDateAndTime.format(myCalendar.getTime()));

I tried this code. It works fine for me. Please try it once
private int pYear = 1970;
private int pMonth = 1;
private int pDay = 1;
static final int DATE_DIALOG_ID = 0;
Then in onCreate:
edt_birth.setKeyListener(null);
edt_birth.setOnTouchListener(new OnTouchListener() {
#SuppressWarnings("deprecation")
#Override
public boolean onTouch(View v, MotionEvent event) {
showDialog(DATE_DIALOG_ID);
return false;
}
});
#Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DATE_DIALOG_ID:
return new DatePickerDialog(this, pDateSetListener, pYear, pMonth,
pDay);
}
return null;
}
private DatePickerDialog.OnDateSetListener pDateSetListener = new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
pYear = year;
pMonth = monthOfYear;
pDay = dayOfMonth;
updateDisplay();
}
};
private void updateDisplay() {
int temp = pMonth + 1;
edt_birth.setText(pDay + "/" + temp + "/" + pYear);
}
This will update your edittext.

Android TimePicker not giving the desired result

Hello I'm trying to calculate user's sleeping hours of 7.5.the app should suggest that the user should be at bed at an exact time. For example, she chooses 7:00 Am as her waking time, the app will suggest that by 11:30 Am she should be going to bed What I tried so far is this:
public class TimepickerActivity extends Activity implements TimePickerDialog.OnTimeSetListener {
Button btn1, btn2;
TimePicker picker;
TextView tv;
private int hour;
private int minute;
static final int TIME_DIALOG_ID = 999;
#Override
public void onCreate( Bundle savedInstanceState ) {
super.onCreate(savedInstanceState);
setContentView( R.layout.activity_timepicker );
btn1 = (Button) findViewById (R.id.btnShow);
btn2 = (Button) findViewById (R.id.btnSleepingTime);
tv = (TextView) findViewById (R.id.textView1);
picker = (TimePicker) findViewById (R.id.timePicker1);
setCurrentTimeOnView();
addListenerOnButton();
}
// display current time
public void setCurrentTimeOnView() {
final Calendar c = Calendar.getInstance();
hour = c.get(Calendar.HOUR_OF_DAY);
minute = c.get(Calendar.MINUTE);
// set current time into textview
tv.setText( new StringBuilder().append(pad(hour))
.append(":").append(pad(minute)));
// set current time into timepicker
picker.setCurrentHour(hour);
picker.setCurrentMinute(minute);
}
public void addListenerOnButton() {
btn1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
showDialog(TIME_DIALOG_ID);
}
});
}
#Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case TIME_DIALOG_ID:
// set time picker as current time
return new TimePickerDialog(this,
timePickerListener, hour, minute,false);
}
return null;
}
private TimePickerDialog.OnTimeSetListener timePickerListener =
new TimePickerDialog.OnTimeSetListener() {
public void onTimeSet(TimePicker view, int selectedHour,
int selectedMinute) {
hour = selectedHour;
minute = selectedMinute;
Calendar c = Calendar.getInstance();
c.add(Calendar.HOUR, - selectedHour);
c.add(Calendar.MINUTE, - selectedMinute);
// set current time into timepicker
picker.setCurrentHour(hour + 7);
picker.setCurrentMinute(minute + 30);
// set current time into textview
//tv.setText(new StringBuilder().append(pad(hour))
// .append(":").append(pad(minute)));
tv.setText( picker.getCurrentHour().toString() + ":" + picker.getCurrentMinute().toString() );
}
};
private static String pad(int c) {
if (c >= 10)
return String.valueOf(c);
else
return "0" + String.valueOf(c);
}
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
// TODO Auto-generated method stub
}
}
When I input 7:00 am as my waking time, the result is giving me 2:30 pm. But it should be 12:30 pm. Any help is appreciated thanks.

No, it's correct. If you input 7:00am + 7.5 hours = 14:30 = 2:30 am. The program is working correctly.
EDIT: you almost did it:
public class TimepickerActivity extends Activity implements TimePickerDialog.OnTimeSetListener {
private static final int SUB_HOUR = -7;
private static final int SUB_MINUTE = -30;
[...]
public void onTimeSet(TimePicker view, int selectedHour,
int selectedMinute) {
// Gets current time
Calendar c = Calendar.getInstance();
// Assign hour set in the picker
c.set(Calendar.HOUR, selectedHour)
c.set(Calendar.MINUTE, selectedMinute);
// Have Calendar calculate the substraction of hours and minutes
c.add(Calendar.HOUR, SUB_HOUR);
c.add(Calendar.MINUTE, SUB_MINUTE);
// Get the hour and the minute calculated
hour = c.get(Calendar.HOUR);
minute = c.get(Calendar.MINUTE);
[...]
Of course this means this previous assignment:
hour = selectedHour;
minute = selectedMinute;
is now useless and you can remove it.
By the way, you didn't take into account the day, e.g. choosing 1:30 am would return 6:00 pm but for the day before.
EDIT: I corrected my code.