Category Archives: JAVA

Mac ERROR launching JD-GUI [How to Solve]

After updating the system, open JD GUI and report the following error:

ERROR launching 'JD-GUI'

No suitable Java version found on your system!
This program requires Java 1.8+
Make sure you install the required Java version.

Solution:
1. Right click JD_GUI icon showing package content

2. Locate the file Universal Java application stub file and open it with a text editor

3. Use https://raw.githubusercontent.com/tofi86/universalJavaApplicationStub/master/src/universalJavaApplicationStub Replace the content in the universal Java application stub with the content in

4. Reopen to use

How to Solve PIP3 install oct2py error

use sudo pip3 install oct2py error: ERROR: Cannot uninstall ‘pexpect’. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
Solution: sudo pip3 install oct2py –ignore-installed pexpect
Install successfuly!

MP Error: ‘getBaseMappe ServiceImpl’ clashes [How to Solve]

ServiceImp error:

‘getBaseMapper()’ in ‘com.baomidou.mybatisplus.extension.service.impl.ServiceImpl’ clashes with ‘getBaseMapper()’ in ‘com.baomidou.mybatisplus.extension.service.IService’; attempting to use incompatible return type

In MyBatis-plus, the general reference package is

com.baomidou.mybatisplus.core.mapper;

Looking at the source code, we can see that both the IService and its implementation class ServiceImpl require the Mapper

<M extends BaseMapper<T>, T>
ServiceImpl<M extends BaseMapper<T>, T> implements IService<T>

Problem solving: check whether the mapper used in the self-defined xxservicei is a subclass of basemapper, and

Mapper generic reference should be consistent with iservice.

[Solved] mybatisplus BaseMapper Error: required a single bean, but 2 were found

1. Error reporting

Two classes inherit com baomidou. mybatisplus. mapper. BaseMapper

Service startup error:

Field baseMapper in com.baomidou.mybatisplus.service.impl.ServiceImpl required a single bean, but 2 were found:

- UserDao: defined in file [D:\projects\test\UserDao.class]

- DepartmentDao: defined in file [D:\projects\test\DepartmentDao.class]

The code is as follows

public interface UserDao extends BaseMapper<UserInfo>{ }

public interface DepartmentDao extends BaseMapper{ }

2. Error reporting reason

Departmentdao did not specify a generic type when inheriting basemapper

3. Solution:

Specifying generics when departmentdao inherits basemapper

public interface DepartmentDao extends BaseMapper<DepartmentInfo>{ }

[Solved] debug error: cloud netflix. eureka. EurekaDiscoveryClientConfiguration (IDEA package normally)

Description of the problem: IDEAL in the program compilation, packaging are whole into, debug on the error, the content is as follows:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration$EurekaHealthCheckHandlerConfiguration': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration$EurekaHealthCheckHandlerConfiguration]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/boot/actuate/health/SimpleStatusAggregator
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1334) ~[spring-beans-5.3.13.jar:5.3.13]
 
     ......
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1326) ~[spring-beans-5.3.13.jar:5.3.13]
    ... 17 common frames omitted
Caused by: java.lang.NoClassDefFoundError: org/springframework/boot/actuate/health/SimpleStatusAggregator
    at org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration$EurekaHealthCheckHandlerConfiguration.<init>(EurekaDiscoveryClientConfiguration.java:64) ~[spring-cloud-netflix-eureka-client-3.1.0.jar:3.1.0]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_251]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_251]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_251]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_251]
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:211) ~[spring-beans-5.3.13.jar:5.3.13]
    ... 19 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.actuate.health.SimpleStatusAggregator
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382) ~[na:1.8.0_251]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[na:1.8.0_251]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355) ~[na:1.8.0_251]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[na:1.8.0_251]
    ... 25 common frames omitted

 

Error Analysis:
Add eureka.client.healthcheck.enabled=true in application.properties files

Solution:
1. add dependency in pom.xml

 <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

 

2. file->invalidate caches/restart

[Solved] Annotation Customize Error: ElementType cannot be resolved to a variable

In the development process, you may use custom annotations (this article uses custom annotations when using JWT) to report an error:

ElementType cannot be resolved to a variable

Manually import packages:

import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.ElementType;

Perfect solution

Springboot2.6X version integrate knife4j error [How to Solve] 

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.13.jar:5.3.13]
	at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[na:na]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.1.jar:2.6.1]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) ~[spring-boot-2.6.1.jar:2.6.1]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) ~[spring-boot-2.6.1.jar:2.6.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:302) ~[spring-boot-2.6.1.jar:2.6.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) ~[spring-boot-2.6.1.jar:2.6.1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290) ~[spring-boot-2.6.1.jar:2.6.1]
	at com.fern.hfet.HfetApplication.main(HfetApplication.java:14) ~[classes/:na]
Caused by: java.lang.NullPointerException: null
	at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
	at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113) ~[springfox-core-3.0.0.jar:3.0.0]
	at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89) ~[springfox-spi-3.0.0.jar:3.0.0]
	at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469) ~[na:na]
	at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:na]
	at java.base/java.util.TimSort.sort(TimSort.java:220) ~[na:na]
	at java.base/java.util.Arrays.sort(Arrays.java:1515) ~[na:na]
	at java.base/java.util.ArrayList.sort(ArrayList.java:1750) ~[na:na]
	at java.base/java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:392) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.13.jar:5.3.13]
	... 14 common frames omitted

Disconnected from the target VM, address: '127.0.0.1:65104', transport: 'socket'

Process finished with exit code 1

The reason for this problem is: springboot2.6.x and the previous version use PATH_PATTERN_PARSER by default, while knife4j’s springfox uses ANT_PATH_MATCHER. Springboot’s yml file configures url matching rules

spring:
  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher

[Solved] Swagger request error: error:getaddrinfo ENOTFOUND

Swagger request error: error: getaddrinfo enotfound

This is the problem I encountered. Maybe everyone encountered it in different ways. I just said the problems I encountered and my solutions
my problem is that when I create a new data table and put it in the test environment, the data table does not move to the test environment, so this error is reported:
solution: import the newly created data table in the test environment (formal environment), and the interface access is normal.

Eclipse: How to Close XML validation (xml file Error)

Eclipse turns off English spell checking and XML validation

To solve the problem, the servlet can run, but the XML file is red

Mode 1:

Windows–> Preferences–> XML –> XML Files –> Validate

Find validate and uncheck build

Mode 2:

Windows–> Preferences–> XML(Wild Web Developer)-> Validate& Resolution

Cancel enable validate

Or change both enable namespaces validate and enable schema based} validate to never

Then click apply and it will be OK

The first one, I don’t know whether it’s my eclipse version or something. I didn’t find that one. The second one can solve this problem. I hope it can help you!!