Before after Ignore Test Beforeclass Afterclass in JUnit 4

Unit 4 uses annotations in Java 5 (annotation), the following is a few annotation introduced by JUnit 4
@Before: Initialization method
@After: Freeing Resources
@Test: Test method, where you can test for expected exceptions and time-outs
@Ignore: Ignored test methods
@BeforeClass: For all tests, execute only once and must be static void
@AfterClass: For all tests, execute only once and must be static void
A JUnit 4 unit test Case execution sequence is:
@BeforeClass –> @Before –> @Test –> @After –> @AfterClass
The order in which each test method is called is:
@Before –> @Test –> @After
Write an example, test it, test it.

 Public classjunit4test {@Before Public voidbefore () {System.out.println ("@Before");} @Test Public voidTest () {System.out.println ("@Test"); Assertequals (5 + 5, 10);} @Ignore @test Public voidTestignore () {System.out.println ("@Ignore");} @Test (Timeout= 50) Public voidtesttimeout () {System.out.println ("@Test (timeout = 50)"); Assertequals (5 + 5, 10);} @Test (Expected= ArithmeticException.class) Public voidtestexpected () {System.out.println ("@Test (expected = exception.class)"); Throw Newarithmeticexception ();} @After Public voidAfter () {System.out.println ("@After"); } @BeforeClass Public Static voidBeforeclass () {System.out.println ("@BeforeClass");    }; @AfterClass Public Static voidAfterclass () {System.out.println ("@AfterClass"); };};

Output results

= = Exception. class ) @After @before@test@after@afterclass

@BeforeClass and @AfterClass	@Before and @After
Only one time can appear in a class	can occur multiple times in a class, that is, you can add these two annotaion tags before the declaration of multiple methods, and the order of execution is indeterminate
Method name does not limit	Method name does not limit
Run only once in a class	Run once before or after each test method
@BeforeClass method that identifies the annotation in the parent class will be executed before the method that identifies the annotation in the current class. @AfterClass method that identifies the annotation in the parent class will execute after the method that identifies the annotation in the current class	@Before method that identifies the annotation in the parent class will be executed before the method that identifies the annotation in the current class. @After method that identifies the annotation in the parent class will execute after the method that identifies the annotation in the current class
Must be declared as public static	Must be declared as public and not static
All methods that are identified as @afterclass are bound to be executed, even if the method that is identified as @beforeclass throws an exception.	All methods identified as @after are bound to be executed, even if the method that identifies the @Before or @Test throws an exception.

@BeforeClass and @AfterClass are very effective for allocating or releasing resources that are "expensive", because they are only executed once in the class. In contrast, using @before and @after is also a wise choice for resources that need to be initialized before each run, or need to be cleaned after running.

Before after Ignore Test Beforeclass Afterclass in JUnit 4