Flash for mobile OSs was discontinued by Adobe a few years ago now. There is an old version available, but might not work on many sites these days, and isn't really safe to use online either as it's unmaintained. Android has never supported Java in a browser for online sites, and again it's been deprecated now AFAIK. Many sites these days just don't use Java any more. There's Javascript, which is supported by Android no problem, and many game sites do use.
Puffin Browser supports the latest Flash server side, could try that, not sure about Java.
https://www.puffinbrowser.com/