spring - java field qualifier best practice -

it practice use proper qualifier between private, protected, private or default. there other reason performance or jvm optimization drawback default used instead of private? example

public class class1{     class2 class2; } 

and variable class2 have been private.

also if variable autowired or injected di framework. framework calls field.setaccessible(true). make difference per performance or optimization.

i think understand motivation question.

the reasons using correct access modifiers on variables in normal java understood. basically, modularity, encapsulation, avoiding unwanted / harmful coupling , on.

what spring?

well true spring can circumvent normal access rules , allow inject private variables. however, understand, have deliberately annotate private fields @autowire or similar occur. going on here spring following "instruction" explicitly declared in source code means of annotation. spring xml-based wiring won't let inject value private field or using private setter.

in light of this, argument spring allows break private encapsulation ... while technically true ... self-serving. sure, can it. have explicitly, deliberately ... design. , happens when objects wired.

by contrast, if sloppy modifiers, , declare every instance variable public or package private, leaving open possibility of sorts of lazy, ill-considered, or accidental breaking of encapsulation. , if (the original author) disciplined, next guy reading / maintaining code can't sure have been disciplined. has check ...

so how "force" toe line?

it best persuade rather force, way force people write decent code project manager / quality manager adopt coding standard, , insist followed. (but can easier said done if management doesn't understand long-term costs of poor quality.)

the real reason have these pesky coding standards code can maintained ... other guy wrote it. manager understand this. pm understand this. programmer understand this.