Paramater or variable name?

Question

Why everyone write variable starts with m? Adapter mApapter? But Android studio suggest Adapter adapter .
what is the good coding practice?which one is very clear to read.
what is use the universal name convention? I saw something like that on php.Adapter pAdapter.

Answer 1

'm' means member of the class. So, if you don't use IDE to highlight your members, then you will understand that it is a member by it's name.

Somtimes people use other prefixes if you discover some variables starting with 'i' or 's' it could also be a variant of the Hungarian Notation

For more info see Why do variable names often start with the letter 'm'?

In Android Coding Style Field Naming Conventions are

• Non-public, non-static field names start with m.
• Static field names start with s.
• Other fields start with a lower case letter.
• Public static final fields (constants) are ALL_CAPS_WITH_UNDERSCORES.

For more info see Android Follow Field Naming Conventions

Answer 2

By taking a look at the Android code-style page you can see that:

• Non-public, non-static field names start with m
• Static field names start with s.
• Other fields start with a lower case letter.
• Public static final fields (constants) are
  ALL_CAPS_WITH_UNDERSCORES.

https://source.android.com/source/code-style.html#follow-field-naming-conventions

Answer 3

Those are naming conventions for the AOSP project, and as many conventions, are a matter of religion more than reason. Those were not recommended neither in the Java Naming Conventions nor in Google´s Java Style Conventions.

In practice each organization or project has it own conventions.

I'd name it "adapter" for instance.