eclipse springboot运行helloworld错误: 找不到或无法加载主类 xxx.xxx.xxx

这个错误，在网上搜找了好久，说是什么jar包冲突，什么环境配置，我经过验证均是正确的，javac java java -version 都没问题，环境变量也OK，各种解释均没有能够解决我的问题，最后好一顿折腾，解决了

shiro 的测试方法

 package com.sharp.forward;

 import org.apache.shiro.SecurityUtils;
 import org.apache.shiro.authc.UsernamePasswordToken;
 import org.apache.shiro.mgt.DefaultSecurityManager;
 import org.apache.shiro.realm.Realm;
 import org.apache.shiro.realm.SimpleAccountRealm;
 import org.apache.shiro.subject.Subject;
 import org.junit.Before;
 import org.junit.Test;

 public class JavaShiroTest extends ShiroApplicationTests{

     SimpleAccountRealm realm = new SimpleAccountRealm("simpleRealm");
     @Before
     public void add() {
         realm.addAccount("张三", "123456");
     }

     @Test
     public void contextLoads() {
     }
     @Test
     public void testAuthenticate() {
 //        三要素，SecurityManager,subject,realm
         DefaultSecurityManager defaultSecurityManager = new DefaultSecurityManager();
 //        SecurityManage设置realm与数据库或缓存相连接
         defaultSecurityManager.setRealm(realm);
 //        SecurityUtils设置SecurityManager可以与主题subject相连接
         SecurityUtils.setSecurityManager(defaultSecurityManager);
 //        获取主题，并通过secutityUtil将securityManager和realm联系起来，
         Subject subject = SecurityUtils.getSubject();
 //        提交主题是通过token提交的
         UsernamePasswordToken token = new UsernamePasswordToken("张三", "123456");
         subject.login(token);
         System.out.println("subject.isAuthenticated(): "+subject.isAuthenticated());

     }

 }

在测试类里面的测试方法报错，

java.lang.Exception: No tests found matching [{ExactMatcher:fDisplayName=testAuthenticate], {ExactMatcher:fDisplayName=testAuthenticate(com.sharp.forward.JavaShiroTest)], {LeadingIdentifierMatcher:fClassName=com.sharp.forward.JavaShiroTest,fLeadingIdentifier=testAuthenticate]] from org.junit.internal.requests.ClassRequest@73c6c3b2
at org.junit.internal.requests.FilterRequest.getRunner(FilterRequest.java:40)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createFilteredTest(JUnit4TestLoader.java:80)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:71)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:46)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:522)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)

然后在主类中写了一个main查看是否报错

然后找解决办法，

说明首先，我是创建的springboot工程，创建的时候，因为之前选择版本的问题，出来的项目总不是完整的项目，需要修改版本，可能是这个原因导致的一些配置发生了变化，现在先看一下我的创建过程，我的项目都是自己搭建的私服

当出现不完整的项目的时候，就把项目的版本修改为适应的版本就可以出来了，可能是由于记忆了，

之前出现题目中的问题是运行其他项目中突然出现的，于是我仍然在同样的环境下建的项目但运行helloworld

就是main方法打印helloworld，控制台同样出现了错误：找不到或无法加载主类的提示，

最终解决办法是：先run build install 此时发现不能成功，提示用的是jre不是jdk，然后修改为jdk，再次运行一切都好了，

然后我再去创建项目，除了将https改为http外，其他的完整项目均能一次加载，不需要修改版本了。

这样解决了，

但是我又重新复现了一下这个问题，发现单单修改了这里有时候还不行，maven install 仍然报jre而不是jdk，同样又出现上述问题，于是我又修改如下地方

项目右键属性，下方修改为jdk,

再次 install 然后再去运行helloworld和测试，完美解决，看来还是jdk在作怪。

测试运行结果

junit变为绿条了

控制台打印结果如下

 16:41:35.128 [main] DEBUG org.springframework.test.context.junit4.SpringJUnit4ClassRunner - SpringJUnit4ClassRunner constructor called with [class com.sharp.forward.JavaShiroTest]
 16:41:35.135 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
 16:41:35.147 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating BootstrapContext using constructor [public org.springframework.test.context.support.DefaultBootstrapContext(java.lang.Class,org.springframework.test.context.CacheAwareContextLoaderDelegate)]
 16:41:35.171 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating TestContextBootstrapper for test class [com.sharp.forward.JavaShiroTest] from class [org.springframework.boot.test.context.SpringBootTestContextBootstrapper]
 16:41:35.189 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Neither @ContextConfiguration nor @ContextHierarchy found for test class [com.sharp.forward.JavaShiroTest], using SpringBootContextLoader
 16:41:35.199 [main] DEBUG org.springframework.test.context.support.AbstractContextLoader - Did not detect default resource location for test class [com.sharp.forward.JavaShiroTest]: class path resource [com/sharp/forward/JavaShiroTest-context.xml] does not exist
 16:41:35.200 [main] DEBUG org.springframework.test.context.support.AbstractContextLoader - Did not detect default resource location for test class [com.sharp.forward.JavaShiroTest]: class path resource [com/sharp/forward/JavaShiroTestContext.groovy] does not exist
 16:41:35.200 [main] INFO org.springframework.test.context.support.AbstractContextLoader - Could not detect default resource locations for test class [com.sharp.forward.JavaShiroTest]: no resource found for suffixes {-context.xml, Context.groovy}.
 16:41:35.201 [main] INFO org.springframework.test.context.support.AnnotationConfigContextLoaderUtils - Could not detect default configuration classes for test class [com.sharp.forward.JavaShiroTest]: JavaShiroTest does not declare any static, non-private, non-final, nested classes annotated with @Configuration.
 16:41:35.284 [main] DEBUG org.springframework.test.context.support.ActiveProfilesUtils - Could not find an 'annotation declaring class' for annotation type [org.springframework.test.context.ActiveProfiles] and class [com.sharp.forward.JavaShiroTest]
 16:41:35.397 [main] DEBUG org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider - Identified candidate component class: file [D:\worksheet\shiro\target\classes\com\sharp\forward\ShiroApplication.class]
 16:41:35.404 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Found @SpringBootConfiguration com.sharp.forward.ShiroApplication for test class com.sharp.forward.JavaShiroTest
 16:41:35.538 [main] DEBUG org.springframework.boot.test.context.SpringBootTestContextBootstrapper - @TestExecutionListeners is not present for class [com.sharp.forward.JavaShiroTest]: using defaults.
 16:41:35.540 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Loaded default TestExecutionListener class names from location [META-INF/spring.factories]: [org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener, org.springframework.boot.test.mock.mockito.ResetMocksTestExecutionListener, org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener, org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener, org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener, org.springframework.test.context.web.ServletTestExecutionListener, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener, org.springframework.test.context.support.DependencyInjectionTestExecutionListener, org.springframework.test.context.support.DirtiesContextTestExecutionListener, org.springframework.test.context.transaction.TransactionalTestExecutionListener, org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener]
 16:41:35.592 [main] DEBUG org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Skipping candidate TestExecutionListener [org.springframework.test.context.transaction.TransactionalTestExecutionListener] due to a missing dependency. Specify custom listener classes or make the default listener classes and their required dependencies available. Offending class: [org/springframework/transaction/interceptor/TransactionAttributeSource]
 16:41:35.593 [main] DEBUG org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Skipping candidate TestExecutionListener [org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener] due to a missing dependency. Specify custom listener classes or make the default listener classes and their required dependencies available. Offending class: [org/springframework/transaction/interceptor/TransactionAttribute]
 16:41:35.593 [main] INFO org.springframework.boot.test.context.SpringBootTestContextBootstrapper - Using TestExecutionListeners: [org.springframework.test.context.web.ServletTestExecutionListener@6e171cd7, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener@402bba4f, org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener@795cd85e, org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener@59fd97a8, org.springframework.test.context.support.DirtiesContextTestExecutionListener@f5ac9e4, org.springframework.boot.test.mock.mockito.ResetMocksTestExecutionListener@123ef382, org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener@dbf57b3, org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener@384ad17b, org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener@61862a7f, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener@441772e]
 16:41:35.596 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.596 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.598 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.598 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.672 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.672 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.676 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.676 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.677 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.682 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.690 [main] DEBUG org.springframework.test.context.support.AbstractDirtiesContextTestExecutionListener - Before test class: context [DefaultTestContext@9f116cc testClass = JavaShiroTest, testInstance = [null], testMethod = [null], testException = [null], mergedContextConfiguration = [WebMergedContextConfiguration@12468a38 testClass = JavaShiroTest, locations = '{}', classes = '{class com.sharp.forward.ShiroApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@76b0bfab, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@2f943d71, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.web.client.TestRestTemplateContextCustomizer@3e57cd70, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5bcea91b], resourceBasePath = 'src/main/webapp', contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]], attributes = map['org.springframework.test.context.web.ServletTestExecutionListener.activateListener' -> true]], class annotated with @DirtiesContext [false] with mode [null].
 16:41:35.691 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved @ProfileValueSourceConfiguration [null] for test class [com.sharp.forward.JavaShiroTest]
 16:41:35.691 [main] DEBUG org.springframework.test.annotation.ProfileValueUtils - Retrieved ProfileValueSource type [class org.springframework.test.annotation.SystemProfileValueSource] for class [com.sharp.forward.JavaShiroTest]
 16:41:35.734 [main] DEBUG org.springframework.test.context.support.TestPropertySourceUtils - Adding inlined properties to environment: {spring.jmx.enabled=false, org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true, server.port=-1}

   .   ____          _            __ _ _
  /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
 ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
  \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
   '  |____| .__|_| |_|_| |_\__, | / / / /
  =========|_|==============|___/=/_/_/_/
  :: Spring Boot ::        (v2.1.0.RELEASE)

 2019-03-02 16:41:36.379  INFO 18776 --- [           main] com.sharp.forward.JavaShiroTest          : Starting JavaShiroTest on litan with PID 18776 (started by litan in D:\worksheet\shiro)
 2019-03-02 16:41:36.382  INFO 18776 --- [           main] com.sharp.forward.JavaShiroTest          : No active profile set, falling back to default profiles: default
 2019-03-02 16:41:39.311  INFO 18776 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
 2019-03-02 16:41:39.904  INFO 18776 --- [           main] com.sharp.forward.JavaShiroTest          : Started JavaShiroTest in 4.153 seconds (JVM running for 5.806)
 2019-03-02 16:41:40.645  INFO 18776 --- [           main] a.s.s.m.AbstractValidatingSessionManager : Enabling session validation scheduler...
 subject.isAuthenticated(): true
 2019-03-02 16:41:41.163  INFO 18776 --- [       Thread-2] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

helloworld运行结果

参考https://www.cnblogs.com/fengan/p/5904445.html，重建project有时也可以解决