Can mods harm your computer?
Minecraft mods don’t harm your computer.
However, occasionally people distribute malware or adware or similar and claim those files are Minecraft mods.
Those can harm your computer.
CurseForge is the de facto primary repository for mods; it should usually be safe..
Does OptiFine harm your computer?
OptiFine is safe. Make sure your using the proper OptiFine site though.
Can jar files harm your computer?
Yes and No. By default java programs can do the same things any native program on your system can do. This includes deleting and replacing any file it can access, depending on your operating system and your user privileges this may affect system critical files.
How do I protect a jar file?
The best you can do is obfuscate the code, but I would recommend against it because it will make tracking down production bugs very difficult because the stack traces will be hard to follow. There is no possibility to protect the code from disassembling. You can use obfuscation tool like ‘proguard’.
Why do we need JAR files?
A JAR (Java Archive) is a package file format typically used to aggregate many Java class files and associated metadata and resources (text, images, etc.) into one file to distribute application software or libraries on the Java platform. … jar files as a zipped file(. zip) that is created by using WinZip software.
Where should jar files go?
As of Java 6, extension JAR files may also be placed in a location that is independent of any particular JRE, so that extensions can be shared by all JREs that are installed on a system. It says that for Windows you should place your extensions here %SystemRoot%\Sun\Java\lib\ext .