Consider a file of Java code that begins with this directive:. All classes defined by this file are part of the package named com. If no package directive appears in a file of Java code, all classes defined in that file are part of a default unnamed package.
As we'll see in Chapter 3, "Object-Oriented Programming in Java" , classes in the same package have special access to each other. Thus, except when you are writing simple example programs, you should always use the package directive to prevent access to your classes from totally unrelated classes that also just happen to be stored in the unnamed package.
A class in a package p can refer to any other class in p by its simple name. And, since the classes in the java. Thus, you can always type String , instead of java. By default, however, you must use the fully qualified name of all other classes. So, if you want to use the File class of the java.
Specifying package names explicitly all the time quickly gets tiring, so Java includes an import directive you can use to save some typing. The import keyword can be used any number of times in a Java file, but all uses must be at the top of the file, immediately after the package directive, if there is one. These classes are guaranteed to be available in all implementations. Your classes have access by default to all classes in java. It contains classes like String , Math , and the "wrapper classes" for the primitive types, for example.
Many Java packages are imported more frequently than others, so you will often see one or more of the following import statements. Classes not placed in a named package belong to the anonymous "default package" associated with the current directory, and when writing small programs, we generally just leave everything in the "default package" for simplicity.
However, packages are there to help us keep our sanity when writing medium to large programs, and we should make use of them.
Suppose I try to create package com. VarunAgw nope, you can play dirty and force conflicts. Other than the conflicts, it make more sense to use OrgName. ProjectName for small projects then — VarunAgw. You'd be flying in the face of convention, but it's your call. Endianness I'm not a java expert, but as to the general pattern this is just another permutation of big-endian vs little-endian, metaphorically speaking. Ed Hastings Ed Hastings 5 5 silver badges 6 6 bronze badges. Golly, never heard endianness used to refer to the reverse-domain namespace scheme..
I hadn't either, until a colleague threw it out in a conversation and spawned some tangential discussion. He ref'd wikipedia as linked to , so apparently it isn't unheard of. I had to relax my literal mind a bit to accommodate this point of view, but I can live with it.
Yeah, this discussion of DNS endianness comes around periodically. RossPatterson: Filesystems, Operating Systems, Faceted Classification Systems, Library Filing Systems, phone numbers, most of them start with the root at the left and then get more specific.
Heck, even most DNS name server configuration files do it that way. So, I'd agree with the Janus crowd. RossPatterson Given their name, I'm surprised that Janus has an opinion on what counts as "the right way around". Show 3 more comments. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
What is it exactly? Its actually package naming convension. How to decide root package name? For example: Domain name: sun. Community Bot 1 1 1 silver badge. Paresh Mayani Paresh Mayani k 69 69 gold badges silver badges bronze badges. SilverbackNet SilverbackNet 2, 16 16 silver badges 28 28 bronze badges. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta. Now live: A fully responsive profile.
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