According to oracle docs: the class name in java should  be nouns, in mixed case with the first letter of each internal word capitalized.Is this just a good practice rule or a mandatory rule?(I'm a beginner so please excuse me if this is too silly)
Class name in java should be camelcase - mandatory or not?
java
This is only a good practice, but about every one follows it. Better readability and, at least Eclipse, you can use all capital letters for intellisense (suggestions).So if you have these variables :myVariablemyFirstVariablemySecondVariableYou can be suggested the last one by typing mSV. Same is applied for classes or interfaces.