Practice-it is a web application to help you practice solving Java programming problems online. Many of the problems come from the University of Washington's introductory Java courses.
To use Practice-it, first create an account, then choose a problem from our list. Type a solution and submit it to our server. The system will test it and tell you whether your solution is correct.
https://practiceit.cs.washington.edu/problem/list
https://google.github.io/styleguide/javaguide.html
Identifiers use only ASCII letters and digits, and, in a small number of cases noted below, underscores. Thus each valid identifier name is matched by the regular expression \w+ .
In Google Style, special prefixes or suffixes are not used. For example, these names are not Google Style: name_, mName, s_name and kName.
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5.2.1 Package names Package names are all lowercase, with consecutive words simply concatenated together (no underscores). For example, com.example.deepspace, not com.example.deepSpace or com.example.deep_space.
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5.2.2 Class names Class names are written in UpperCamelCase.
Class names are typically nouns or noun phrases. For example, Character or ImmutableList. Interface names may also be nouns or noun phrases (for example, List), but may sometimes be adjectives or adjective phrases instead (for example, Readable).
There are no specific rules or even well-established conventions for naming annotation types.
Test classes are named starting with the name of the class they are testing, and ending with Test. For example, HashTest or HashIntegrationTest.
- 5.2.3 Method names Method names are written in lowerCamelCase.
Method names are typically verbs or verb phrases. For example, sendMessage or stop.
Underscores may appear in JUnit test method names to separate logical components of the name, with each component written in lowerCamelCase. One typical pattern is _, for example pop_emptyStack. There is no One Correct Way to name test methods.
- 5.2.4 Constant names Constant names use CONSTANT_CASE: all uppercase letters, with each word separated from the next by a single underscore. But what is a constant, exactly?
Constants are static final fields whose contents are deeply immutable and whose methods have no detectable side effects. This includes primitives, Strings, immutable types, and immutable collections of immutable types. If any of the instance's observable state can change, it is not a constant. Merely intending to never mutate the object is not enough. Examples:
// Constants
static final int NUMBER = 5;
static final ImmutableList<String> NAMES = ImmutableList.of("Ed", "Ann");
static final ImmutableMap<String, Integer> AGES = ImmutableMap.of("Ed", 35, "Ann", 32);
static final Joiner COMMA_JOINER = Joiner.on(','); // because Joiner is immutable
static final SomeMutableType[] EMPTY_ARRAY = {};
enum SomeEnum { ENUM_CONSTANT }
// Not constants
static String nonFinal = "non-final";
final String nonStatic = "non-static";
static final Set<String> mutableCollection = new HashSet<String>();
static final ImmutableSet<SomeMutableType> mutableElements = ImmutableSet.of(mutable);
static final ImmutableMap<String, SomeMutableType> mutableValues =
ImmutableMap.of("Ed", mutableInstance, "Ann", mutableInstance2);
static final Logger logger = Logger.getLogger(MyClass.getName());
static final String[] nonEmptyArray = {"these", "can", "change"};
These names are typically nouns or noun phrases.
