The Java Runtime Environment, or jre for short, is a java runtime environment for android (Jre4Android) used to execute Java programs. It can run jar and class files. Support java swing gui. This app can open jar and run jar file (Java version is 17, Jre4Android pro supports java 21: https://play.google.com/store/apps/details?id=com.coobbi.jre.pro) The effect of this app is the same as the command below: java -jar xxx.jar This app can also open class and run .class file, the effect is same