20145311 "Java Program design" Seventh week study summary textbook Learning content Summary 12th Chapter LAMBDA
Lambda expressions make programs more concise and can be processed in parallel when designed in parallel.
The 13th chapter time and date 13.1time&&date
13.1.1 Measurement of Time
1, Greenwich Mean Time (GMT) abbreviated to GMT to observe the sun
2, Universal time (World) UT
3. International Atomic Time (International Atomic) TAI
4. Coordinated Universal time (World coordinated) UTC
5, Unix time with January 1, 1970 00:00:00 as the starting point
6. Epoch
The current time actually refers to UTC time
13.1.2 Calendar
1. Julian calendar (Julian calendar) four years a leap
2. Gergorian Calendar (Gregorian calendar)
3. ISO 8601 Standard
13.1.3Time Zones (timezone)
The number of milliseconds in a year is notsimple 3651000
13.2date&&calendar
13.2.1Date
The epoch milliseconds can be obtained using each gettime of the date instance, and the **data instance is used only as a moment on the timeline
13.2.2DataFormat (formatted time date)
DataFormat can be used to process the string format, respectively, Getdateinstance, Gettimeinstance, getdatetimeinstance
Directly build SimpleDateFormat, you can customize the string format the parse method can dissect a specified string into a date instance
13.2.3Calendar
After obtaining the calendar instance, you can get the date information, can be set, can be calculated to change
13.2.4TimeZone
TimeZone Getdefault can get information for the default time zone
13.3 New Time Date API
13.3.1 Machine Time View
The date instance represents only the time information of the machine view
13.3.2 Human Time Perspective
Lockaldatetime, Localdate, localtime are not time zone information
On top of those classes can be supplemented by using zoneddatetime, etc.
Gets the month through the GetValue () method instead of using the oridinal () (starting from 0) method
13.3.3 the operation of time
Calendar can be used for time operations, JDK8 also provides a more convenient time calculation method and output format, operation of the corresponding temporal class can be
13.3.4 Calendar System Design
Classes in the Java.time.chrono class with relevant calendar systems
Problems in teaching materials learning and the solving process
The date instance can only be used as an instant on the timeline, need to be converted, and the time of year is not 365*24*60*60*1000, there are many different. Machine time and human time is still different, the design process should be used correctly, in the human time point of view also pay attention to the different calendars and time zone problems, otherwise there will be some inaccuracies (time is quite complicated).
Problems in code debugging and the resolution process
Other (sentiment, thinking, etc., optional)
This week's study is mainly time and date, in fact, Java has such a number of classes, the operation of these classes can be expressed in the corresponding time and some output format of the time to express, there is the time to operate, the most critical is good at using the API help documents, when needed to be able to use these classes flexibly.
Learning progress Bar
|
Lines of code (new/cumulative |
Blog volume (cumulative/target) |
Study time |
Estimating Learning Time |
Actual learning Time |
Important growth |
Goal |
5000 rows |
30 Articles |
400 hours |
|
|
|
First week |
150/150 |
2/2 |
15 |
|
|
|
Second week |
500/650 |
3/4 |
15 |
|
|
|
Third week |
500/1150 |
4/5 |
14 |
|
|
|
Week Four |
600/1750 |
5/6 |
15 |
|
|
|
Week Five |
500/2250 |
6/7 |
9 |
|
|
I didn't learn much this week. |
Week Six |
300/2350 |
7/8 |
10 |
|
|
Learning is still untrue, but better than last week |
Seventh Week |
This week wrote about 300 lines of code (including experiments), Some of the code is directly pasted run and look at the results |
10/10 |
8~9h |
10h |
8h~9h |
This week's study content is mainly the time, the date correlation class application, Compared to the previous chapters, it's a bit simpler, The actual learning time is less than the estimated learning time, The time spent reading is about the same as the estimate, But write code, debug, do practical application, Learning Java experiments related debugging skills, testing skills time or less, or a little lazy. |
Resources
- Java Learning Notes (8th Edition)
- Java Learning Note (8th Edition) Learning Guide
- ...
20145311 Java programming Seventh week of study summary