ADDITIONAL SYSTEM INFORMATION :
â– Environment
・OS: Edition: Windows 10 Enterprise 2016 LTSB, Version:1607, OS Build: 14393.2515
・Java Version:"1.8.0_181"
               Java(TM) SE Runtime Environment (build 1.8.0_181-b13)
               Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)
・VM args:-XX:+PrintGCTimeStamps
          -XX:+PrintGCDateStamps
          -Xloggc:%LOG%/gc.log
          -Xmx2048m
          -client
          -Dsun.nio.cs.map=x-windows-iso2022jp/ISO-2022-JP
          -Dsun.java2d.d3d=false
・Locale:Language(ISO 639): Japanese (ja)
         Country(ISO 3166): Japan (JP)
         Variant: -
         Script(ISO 15924): (Jpan)
         Language Tag: ja-JP


A DESCRIPTION OF THE PROBLEM :
â–  Event
 ãƒ» Swing JTextField is no longer focused
 ãƒ» The grid could be selected
 ãƒ» Windows apps, etc. were working without any problems

â– Referenced information
  ■ Focus on JTextField
  https://www.atmarkit.co.jp/bbs/phpBB/viewtopic.php?topic=36333&forum=12&start=8
  -> Discover a very close event. No description of cause and solution

  â– Oracle Bug Database
  https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4199374
  https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4475409
  https://bugs.java.com/bugdatabase/view_bug.do?bug_id=7147075
  -> Solved by about 10 years ago, or does not reproduce even if the sample code is run in the same environment
  â– community.oracle.com
  https://community.oracle.com/thread/2512532?tstart=0
  
  â– p2p.wrox.com
  https://p2p.wrox.com/java-gui/1502-focus-problem-jtextfield-inputverifier.html
  
  â– List of bugs since JRE version Java8 181
  https://www.oracle.com/technetwork/java/javase/2col/8u192-bugfixes-4479410.html
  -> [# 3] [JDK-8200353] Shift key or Capslock key does not work in Textfield after typing with accents
  
  https://www.oracle.com/technetwork/java/javase/2col/8u202-bugfixes-5209341.html
  -> [# 3] [JDK-8130655] OS X: If the window included in the text field is owned by EmbeddedFrame,
     No keyboard input in text field
  -> [# 4] [JDK-8205479] OS X: requestFocus() does not work properly for embedded frames


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
â–  Condition of occurrence
unknown. Unreproducible.
* Occurred four times a year since the following environment.
  We use about 8 hours on weekdays.
  OS Before the following environment, the OS was Windows7, which never occurred in half a year.
* Investigate from heap dump / thread dump / web
 ãƒ» On a heap dump, the JTextField properties appear active and touchable even when the event occurs
 ãƒ» No abnormalities such as waiting state after being locked from thread dump
 ãƒ» I tried to automatically execute a large number of operations that were performed before JTextField became uninputable, but could not reproduce
 ãƒ» There are several similar events on the Oracle Java Bug Database and on Web pages, but all have been fixed or closed without being reproduced
 ãƒ» Looking at the bug fix history of the JRE from the version we are using to the latest version, there is a close fix for MacOS but not for Windows

* Since it cannot be reproduced, the operation has not been verified with the latest Java version.


FREQUENCY : rarely