Introduction

JUnit annotations are used to setUp and tearDown test fixtures. Different annotations in
JUnit4 are:

@BeforeClass
@AfterClass
@Before
@After

@BeforeClass and @AfterClass

@BeforeClass annotated method will be executed once before all the tests in the class. This method would be used to perform one time initialization.

On the other hand, @AfterClass annotated method will be executed once after all the tests in the class. This method is used to release any resources acquired during the tests etc.

@Before and @After

@Before annotated method will run before each test method in the class. For example, if you have 3 test annotated method, @Before method will run 3 times before each @Test annotated method.

On the other hand, @After annotated method will run after each test method in the class.

@Test annotation can be found here: JUnit @Test annotation

Example

In the below example, we will see the order of JUnit annotations.

package com.testingdocs.junit;
import static org.junit.Assert.*;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

/**
 * A sample JUnit4 Test annotation demo
 * class
 */

/**
 * @author testingdocs
 *
 */
public class SampleJUnit4TestCase {

 /**
 * @throws java.lang.Exception
 */
 @BeforeClass
 public static void setUpBeforeClass() throws Exception {
 System.out.println("@BeforeClass");
 }
 

 /**
 * @throws java.lang.Exception
 */
 @AfterClass
 public static void tearDownAfterClass() throws Exception {
 System.out.println("@AfterClass");
 }

 /**
 * @throws java.lang.Exception
 */
 @Before
 public void setUp() throws Exception {
 System.out.println("@Before");
 }

 /**
 * @throws java.lang.Exception
 */
 @After
 public void tearDown() throws Exception {
 System.out.println("@After");
 }

 @Test
 public void firstTestMethod() {
 System.out.println("Test method 1");
 fail("Not yet implemented1");
 }
 
 @Test
 public void secondTestMethod() {
 System.out.println("Test method 2");
 fail("Not yet implemented2");
 }
 
 @Test
 public void thridTestMethod() {
 System.out.println("Test method 3");
 fail("Not yet implemented3");
 }
}