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How to convert an object to byte array in JAVA. The easiest way to convert an object to byte array is to use the Object Serialization ObjectOutputStream. However, there is a problem that object serialization is compatible only with Java. Object serialization cannot be used for socket communication with heterogeneous (c language, .NET, etc.). So the method I found is to use ByteArrayOutputStream...

This error occurred when I was trying to use RSA private key and public key in Java. ■ Error Exception in thread "main" java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: invalid key format at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:252) at java.security.KeyFactory.generatePrivate(KeyFactory.java:372) at Main.main(Main.java:43) Caused b..

This automatic printing method allows infinite ink printer nozzles to be managed without clogging. The printer nozzle will become clogged if it is not used for a long time. If the nozzle is blocked, it will cost more than 100,000 won to replace the head. To prevent the nozzle from clogging, you can print it twice a week, which is a hassle if you don't have a lot of printing. To solve this proble..

Buyers of the Infinite Ink Printer may have thought that just charging ink would no longer require maintenance, but there is probably something most of the time that they don't know. An ink pad for collecting waste ink Using a printer for a period of time makes printing impossible with the following message: Printer's ink pad is at the end of its service life. please contact epson support ■ Rela..

This is an error-solving method that occurs when you run a Tomcat in Eclipse. This usually occurs when you change the JAVA version or Tomcat version. java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException ■ Cause This occurs because the servlet.jar version is not compatible with the Tomcat version. ■ Solution The following is the specification specified in Tomcat, and yo..

Here's an example of adding Daum's advertising banner Adfit to an Android app. 1. Download SDK 1.1 Download AdfitSDK.aar file provided by adfit 1.2 Copying AdfitSDK.aar file to app/libs directory in project 2. Add aar to build.grade(app) 1 2 3 4 5 6 7 8 9 repositories { flatDir { dirs 'libs' } } dependencies { implementation name: 'AdfitSDK-3.0.5', ext: 'aar' } Colored by Color Scripter cs 3. Mo..

Here's an example of adding Google's advertising banner Admob to an Android app. 1. Add to build.grade(app) 1 2 3 dependencies { implementation 'com.google.android.gms:play-services-ads:17.1.1' } Colored by Color Scripter cs 2. Modify Layout 1 2 3 4 5 6 7 8 9 10 cs ※ Enter the issued Unit ID. 3. Modify Activity 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 import com.google.a..