Java变量未在JUnit测试类中分配

Question

I found something strange in my project. I create a test class using JUnit to test my service layer. The service layer itself is not my question. My problem is, I don't know why after I assigned a value to an int variable in my first test method, and then when I try to use that value in the second test method, the variable value is 0

Executed in order because I use @FixMethodOrder(MethodSorters.NAME_ASCENDING)

int id;

@Test
public void firstMethodToTest() {
    id = 10;
    System.out.println(id); // here printed correctly 10
}

@Test
public void secondMethodToTest() {
    System.out.println(id); // here printed 0
}

I also try to change int to Integer but it returns null not 0 anymore. I wonder if in JUnit Test class like this, Java variable acts differently. Thanks.

Answer 1

Thanks to @Ivan for giving me a clue to the answer

For each test method (the method annotated with @Test ), a new instance of YourTestClass will be created. This is the behavior of Junit.

So, the point is if you want to use a class member for all test methods, just declare the variable as static. In my case: static int id;