importing things in java is causing cannot resolve error

How to get rid of this error? It's my first time using Java

You need to add the external library that you want to use to your project.

To do that, first download the .jar file of the library that you want to use. You can find the latest .jar release of the json library at mvnrepository.com or on this github repository.

In IntelliJ:

1. Go to File -> Project Structure
2. Click on Modules
3. Click on Dependencies tab
4. Click on + sign
5. Select 1 JARs or directories
6. Select the .jar file you just downloaded
7. Click Apply

Now you can import org.json.JSONArray; or import org.json.JSONObject; in your project without an error.

Note: you should really use some type of dependency management tool like for example Maven like others already suggested.

Right click the project, add framework support, add maven, and inside the pom.xml file that maven created, add the following code:

<dependencies>
<dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20200518</version>
</dependency>
</dependencies>

Then click the little refresh button inside the maven tab on the right of the screen.

Now you should be able to use the json library. This is how you use external libraries using maven, it's way faster than importing external jar's manually.

Hope it helps, if you have any other question just leave a comment

Problem is you can't import those packages because you don't have them with you.To solve this you need add a Jar file externally which contains those packages.
Try using a project management tool like Maven[Commonly use for dependency management] or try to add that missing Jar files manually by downloading them through the internet or through the maven central repository.