Spring boot error : Constructor threw exception

I'm a new guy to learn spring boot. I want to learn @Async function how to work in spring boot. I create new spring boot and put the code. Everything is great, I got the result.
When I put the code in to my other project. I got error and I don't know what happen.

web: https://morosedog.gitlab.io/springboot-20190421-springboot33/

        StudentRestController.java
import com.luv2code.demo.code.CompleteAsyncTask;
import com.luv2code.demo.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.concurrent.CompletableFuture;
@EnableAsync
@RestController
@RequestMapping("/api")
public class StudentRestController {
//define endpoint for "/student" - return a list of students
@Autowired
private CompleteAsyncTask completeAsyncTask;
@GetMapping("/students")
public String getStudents() throws Exception {
long start = System.currentTimeMillis();
CompletableFuture<String> one = completeAsyncTask.doTaskOne();
CompletableFuture<String> two = completeAsyncTask.doTaskTwo();
CompletableFuture<String> three = completeAsyncTask.doTaskThree();
CompletableFuture.allOf(one, two, three).join();
System.out.println("Total time spent: " + (System.currentTimeMillis() - start));
System.out.println(one.get());
System.out.println(two.get());
System.out.println(three.get());
return "";
}
}
-----------------------------------------------------------------------------------
package com.luv2code.demo.code;
import java.util.Random;
import java.util.concurrent.CompletableFuture;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;
@Component
public class CompleteAsyncTask {
public static Random random = new Random();
@Async
public CompletableFuture<String> doTaskOne() throws Exception {
System.out.println("Start doing asynchronous tasks one");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("complete asynchronous task one，time consuming：" + (end - start) + "millisecond");
return CompletableFuture.completedFuture("Task one completed");
}
@Async
public CompletableFuture<String> doTaskTwo() throws Exception {
System.out.println("Start doing asynchronous tasks two");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("complete asynchronous task two，time consuming：" + (end - start) + "millisecond");
return CompletableFuture.completedFuture("Task two completed");
}
@Async
public CompletableFuture<String> doTaskThree() throws Exception {
System.out.println("Start doing asynchronous tasks three");
long start = System.currentTimeMillis();
Thread.sleep(random.nextInt(10000));
long end = System.currentTimeMillis();
System.out.println("complete asynchronous task three，time consuming：" + (end - start) + "millisecond");
return CompletableFuture.completedFuture("Task three completed");
}
}
--------------------------------------------------------------------------------------
run result
2023-07-27T14:33:16.459+08:00  INFO 20612 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 1 ms
Start doing asynchronous tasks one
Start doing asynchronous tasks two
Start doing asynchronous tasks three
complete asynchronous task three，time consuming：1055millisecond
complete asynchronous task two，time consuming：3981millisecond
complete asynchronous task one，time consuming：6468millisecond
Total time spent: 6475
Task one completed
Task two completed
Task three completed
------------------------------------------------------------------------------------
error message
Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.
2023-07-27 14:25:29.832 [restartedMain] ERROR org.springframework.boot.SpringApplication - Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'testController' defined in file [D:\xxxxx\testController.class]: Failed to instantiate [com.xxx.testController]: Constructor threw exception
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1314)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1199)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:560)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:520)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:326)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:324)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:973)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:917)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:584)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:732)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:310)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1304)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1293)
at com.xxx.mainApplication.main(mainApplication.java:20)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.xxx.testController]: Constructor threw exception
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:224)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1308)
... 22 common frames omitted
Caused by: java.lang.Error: Unresolved compilation problems: 
The import com.xxx.CompleteAsyncTask cannot be resolved
CompleteAsyncTask cannot be resolved to a type
at com.xxx.testController.<init>(testController.java:61)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:198)
... 24 common frames omitted

Other_project
test_controller --->call CompleteAsyncTask.java

I put this code in test_controller and show error.

@Autowired
private CompleteAsyncTask completeAsyncTask;

can you please check your import once. Error indicates controller was not recognized.

Caused by: java.lang.Error:<b> Unresolved compilation problems:
The import com.xxx.CompleteAsyncTask</b> cannot be resolved
CompleteAsyncTask cannot be resolved to a type

Verify Package Structure: Ensure that the CompleteAsyncTask class is in the correct package. For example, if the CompleteAsyncTask class is in the package com.luv2code.demo.code, make sure it is in the correct folder structure within your project.

make sure to include it in the component scanning by using @ComponentScan annotation in your main application class. For example:

@SpringBootApplication
@ComponentScan(basePackages = {"com.luv2code.demo.code", "com.luv2code.demo.entity", "com.luv2code.demo.rest"})
public class MainApplication {
// Main method and other configurations
}

I will show how to slove the question.
"com.luv2code.demo.contoller" is first one in the ComponentScan.
So, I change "com.luv2code.demo.code" position to first.

Origin
@SpringBootApplication
@ComponentScan(basePackages ={"com.luv2code.demo.contoller","com.luv2code.demo.code", "com.luv2code.demo.entity", "com.luv2code.demo.rest"})
public class MainApplication {
// Main method and other configurations
}
new
@SpringBootApplication
@ComponentScan(basePackages = {"com.luv2code.demo.code","com.luv2code.demo.contoller", "com.luv2code.demo.entity", "com.luv2code.demo.rest"})
public class MainApplication {
// Main method and other configurations
}

Right now, I can run my project.