First cut for basics of java 8 date time api

core-java-8/src/main/java/com/baeldung/datetime/UseDuration.java

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+package com.baeldung.datetime;
+
+import java.time.Duration;
+import java.time.LocalTime;
+import java.time.Period;
+
+public class UseDuration {
+    
+    public LocalTime modifyDates(LocalTime localTime,Duration duration){
+        return localTime.plus(duration);
+    }
+    
+    public Duration getDifferenceBetweenDates(LocalTime localTime1,LocalTime localTime2){
+        return Duration.between(localTime1, localTime2);
+    }
+}

core-java-8/src/main/java/com/baeldung/datetime/UseLocalDate.java

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+package com.baeldung.datetime;
+
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.TemporalAdjusters;
+
+public class UseLocalDate {
+    
+    public LocalDate getLocalDateUsingFactoryOfMethod(int year, int month, int dayOfMonth){        
+        return LocalDate.of(year, month, dayOfMonth);
+    }
+    
+    public LocalDate getLocalDateUsingParseMethod(String representation){        
+        return LocalDate.parse(representation);
+    }
+    
+    public LocalDate getLocalDateFromClock(){        
+        LocalDate localDate = LocalDate.now();
+        return localDate;
+    }
+    
+    public LocalDate getNextDay(LocalDate localDate){       
+        return localDate.plusDays(1);
+    }
+    
+    public LocalDate getPreviousDay(LocalDate localDate){        
+        return localDate.minus(1, ChronoUnit.DAYS);
+    }
+    
+    public DayOfWeek getDayOfWeek(LocalDate localDate){        
+        DayOfWeek day = localDate.getDayOfWeek();
+        return day;
+    }
+    
+    public LocalDate getFirstDayOfMonth(){        
+        LocalDate firstDayOfMonth = LocalDate.now().with(TemporalAdjusters.firstDayOfMonth());
+        return firstDayOfMonth;
+    }
+    
+    public LocalDateTime getStartOfDay(LocalDate localDate){        
+        LocalDateTime startofDay = localDate.atStartOfDay();
+        return startofDay;
+    }
+}

core-java-8/src/main/java/com/baeldung/datetime/UseLocalDateTime.java

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+package com.baeldung.datetime;
+
+import java.time.LocalDateTime;
+
+public class UseLocalDateTime {
+    
+    public LocalDateTime getLocalDateTimeUsingParseMethod(String representation){        
+        return LocalDateTime.parse(representation);
+    }
+
+}

core-java-8/src/main/java/com/baeldung/datetime/UseLocalTime.java

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+package com.baeldung.datetime;
+
+import java.time.LocalTime;
+import java.time.temporal.ChronoUnit;
+
+public class UseLocalTime {
+    
+    public LocalTime getLocalTimeUsingFactoryOfMethod(int hour, int min, int seconds){        
+        LocalTime localTime = LocalTime.of(hour, min, seconds);
+        return localTime;
+    }
+    
+    public LocalTime getLocalTimeUsingParseMethod(String timeRepresentation){        
+        LocalTime localTime = LocalTime.parse(timeRepresentation);
+        return localTime;
+    }
+    
+    public LocalTime getLocalTimeFromClock(){        
+        LocalTime localTime = LocalTime.now();
+        return localTime;
+    }
+    
+    public LocalTime addAnHour(LocalTime localTime){
+        LocalTime newTime = localTime.plus(1,ChronoUnit.HOURS);
+        return newTime;
+    }
+    
+    public int getHourFromLocalTime(LocalTime localTime){        
+        return localTime.getHour();
+    }
+    
+    public LocalTime getLocalTimeWithMinuteSetToValue(LocalTime localTime, int minute){        
+        return localTime.withMinute(minute);
+    }
+}

core-java-8/src/main/java/com/baeldung/datetime/UsePeriod.java

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+package com.baeldung.datetime;
+
+import java.time.LocalDate;
+import java.time.Period;
+
+public class UsePeriod {
+    
+    public LocalDate modifyDates(LocalDate localDate,Period period){
+        return localDate.plus(period);
+    }
+    
+    public Period getDifferenceBetweenDates(LocalDate localDate1,LocalDate localDate2){
+        return Period.between(localDate1, localDate2);
+    }
+}

core-java-8/src/main/java/com/baeldung/datetime/UseToInstant.java

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+package com.baeldung.datetime;
+
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.util.Calendar;
+import java.util.Date;
+
+public class UseToInstant {
+    
+    public LocalDateTime convertDateToLocalDate(Date date){
+        LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault());
+        return localDateTime;
+    }
+    
+    public LocalDateTime convertDateToLocalDate(Calendar calendar){
+        LocalDateTime localDateTime = LocalDateTime.ofInstant(calendar.toInstant(), ZoneId.systemDefault());
+        return localDateTime;
+    }
+}

core-java-8/src/main/java/com/baeldung/datetime/UseZonedDateTime.java

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+package com.baeldung.datetime;
+
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+
+public class UseZonedDateTime {
+    
+    public ZonedDateTime getZonedDateTime(LocalDateTime localDateTime,ZoneId zoneId){        
+        ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, zoneId);
+        return zonedDateTime;
+    }
+}