I went to the Java Women's Club # 1

June 11, 2017 Java Women's Club

[Tokyo] [Women / Men with women only] A full-scale introduction to Java! !! !! I will invite the author (* ´∀` *) #javajo

1. 13: 30-13: 45 Venue Description & Java Women's Club

2. 13: 45-14: 40 Self-introduction

--What is the Java Women's Club? Click here for details --Next time 7/9 ★ From Java Women's Club to the world ★ (It seems that you can hear from the JCP secretariat) --You can hear an interesting story from the author of a full-scale introduction to Java

――Participants are different ――Is there many people who say up to Java7? --There is also a front-end engineer --Two men. (It comes unexpectedly.)

3. [Extra] Logs and Exceptions (Introduction to Java)

--AcroquestTechnorogy Mr. Murata ――Even if you know Java, you can only do it when you come to the development site ... So you wrote the book.

--What should be output to the log? ――It can be difficult for people to understand when there are various parties involved.

--What should be decided in log output? --Log level definition --Log operation level --Log format --Log output format (rotation)

--Log implementation --isDebugEnabled Police (laughs) ――It seems that it will be replaced with a placeholder even if you don't bother to concatenate the strings now.

--Log operation --Log level can be set for each package --Dynamic setting is possible (it can be changed temporarily)

--Type of exception

• Exception
• RuntimeException
• Error

--Basics of exception handling

• try ～ catch ～ finally --try ~ with ~ resources (It's convenient, isn't it?)
• multi catch --Do not wipe out exceptions (let's include exceptions in the log)

--Application method design and exception handling --Determine the exception handling method in the application method design. --What exception ――Where and how to handle --Consider a mechanism to handle exceptions in common

4. 14: 00-15: 30 Full-scale introduction to Java -from old Java to modern Java

--AcroquestTechnorogy Mr. Tanimoto --Rewrite what was written in the old version in hands-on format to the new one --for-each / enumeration --String concatenation - LocalDate

5. 15: 40-16: 25 Introduction to Stream API Stream Kihon that I can't hear anymore

――Why use it? ――Because you will use it in the way of thinking in the future?

• Stream --Can be described concisely --You can aggregate collections, etc. ――It doesn't necessarily mean that you have to use it (it doesn't make sense to write complicated things by force / new things are not always great!)

--Lambda expression --To concisely represent an interface that has only one method to implement. --Replace the contents of the anonymous class

--Functional face --Interface with only one method to implement (Runnnable, etc.)

--Kihon grammar of lambda

  (argument) -> {processing}

--Argument type can be omitted --Return and {} can be omitted if the process is one line --Method reference (can be omitted if one argument is clear) System :: out :: println

• Stream API --Make, operate, put together --Create (Collection # stream / Arrays # stream / entrySet # stream / Files # lines / BufferedReader # lines) --Operate (intermediate operation: conversion and filtering) map / filter --There is also limit / distinct / sorted. --It is difficult to process several elements at once (multi-line log file processing, etc.) --You can't branch with filter (even if you have one Stream) Can you use flatMap? --Collect (Termination operation: Lst, Map, and aggregate. Operation to retrieve as a result) (collect / Collectors) --forEach / max. Min / findFirst etc. ――Of course you can only do it once.

――Why you should learn Stream API ――I think it's a pain to learn, but ... (I don't feel it's worth learning ...) --It is important to handle Stream. (The flow of the river going on ...) --Handling Web requests, queuing processing, etc. for which the upper limit is unknown (HotStream) --Java 8's Stream API handles ColdStream. (Those whose upper limit is visible) --Non-blocking asynchronous API (RxJava / Reactor) --All of this will be described in the form of Stream API. ――The coming era will be an era of handling large amounts of data requests, so you should prepare for that.

6. 16: 35-17: 05 Writing Secrets-Introduction to Java Book Writing

• Originally --It was serialized in Nikkei software (Java code that is cool, code that is not cool)
  • from old java to modern java ――In writing, I had a great Java person RV, but it was messed up ... --At night, I went to the family restaurant and wrote (the value set was written on the Mac). --There is a support site on GitHub (the errata is here)
  • javabook-support

7. 17:05～17:20 AMA

• nothing special

8. Impressions

It's a pretty BBA, so I hesitated to go, but I enjoyed it. I also bought the books mentioned above, but I think they are good books.

★ I want people like this to read it ★

1. Ojisan, Obasan, whose history of Java stops at around 1.4, 5 (I fall into this category)
2. I know how to use the basic API, but beginners who want to take a step forward from there