The test object is created on the outside of the main method 10

The upstairs one is also a solution, but there is another solution, which you can write in the main method:

test3 test = new test3();

The reason is the same: the static method cannot directly call the non-static method, it must be called again by a new object, and the static method can be called directly in the non-static method, because the static method belongs to the class, not to a certain instance object, so first, you either add the static modifier in front of the attribute t of the test3 class, or in the main method, a new test3 instance object, This allows you to call the non-static member of test3 in the main method!

;Reported 2 errors

You know, there are two things in a class, one is a property and the other is a method, and the main method is the method t t = new t();

It's the property but you're wrong here, so it will; Error.

There are two things wrong. 1.to static t t = new t(); Since the main function is static, any other method or property used must also be declared static.

2.After changing it, it will still report an error, because your; Written incorrectly, instead;

public class fortest;

fortest ft=new fortest();new a current method.

Call the method below.

public void a(int arr);}

Unit tests can be done with junit, and there's no need to create a main method per class.

Each class creates a main method to run each method of the class, novices can use this method for unit testing, and later can use junit for unit testing, one method to test one method, both can be, depending on which one you prefer.

In this case, each class can be run separately, and only the main method can be run!! You can also use Junit for unit testing, which is more convenient and flexible.

1 Introduce the class bimport in package2 in package1;

class a

2. Create with the full package name and class name.

class a}

import package2.*;Import all the classes in package2.

class a}

You can configure Junit to test modules and test only a certain function (for example, an operation in a DAO).

You write an output print statement in the main method and the normal thread method, which is printed first, which takes precedence.

You can write a test class to test. In fact, the main method can also be written.