How do I get a value from an address using Java?

For an obfuscation program I am writing in Java, I need to find a way to get a value at a specific address. For example, in a program I opened in a hex editor, at the address 0000001F is the hex value "00". Furthermore, is it possible to write to a specific memory address? For example 开发者_运维问答writing to 0000001F and changing it from "00" to for example, "FF"

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To answer your first question, you can open a file as a binary stream and read whatever you want from it. That won't do much in the way of the classloader, but if you have a custom classloader that manipulates the file and converts it at runtime into a class that is valid and loaded by the JVM, that is certainly theoretically possible. I would wonder what the point is, though, as the classloader itself would not be obfuscated in this manner.

To answer your second question, no you cannot write directly to a memory address with Java. You could call a function via JNI which could do so (outside of the JVM memory allocation).

It sounds to me like you are using the wrong language for what you want to do.

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You are using the wrong language. C or C++ would be better choices because you can easily call operating system libraries (on most systems) and attempt to access the memory at a particular location.

Most POSIX-compliant operating systems implement mmap which allows you to map memory at a particular location in the current processes address space.