Anomalies seen during the interview

executive summary ：checked/unchecked What's the difference between exceptions ？

1️⃣checked： Generally, it refers to the external conditions that cannot be directly controlled by the program , It refers to a class that needs to be checked when compiling exception, Must be used in the user program try catch Mechanism processing or through throws Leave it to the caller . This kind of anomaly , Mainly refers to except Error as well as RuntimeException And its subclasses .
2️⃣unchecked： It refers to those exceptions that do not need to be handled at compile time . stay java In the system , be-all Error as well as RuntimeException And its subclasses are unchecked abnormal . Again, it is understood visually and frankly that there is no need try catch And other mechanisms , Think of it as unchecked It's abnormal .

One 、java.lang.IllegalArgumentException: Path cannot be null

2019-06-20 09:49:11,120 [main-EventThread] ERROR [org.apache.curator.framework.imps.CuratorFrameworkImpl:566] - Watcher exception
java.lang.IllegalArgumentException: Path cannot be null
        at org.apache.curator.utils.PathUtils.validatePath(PathUtils.java:48)
        at org.apache.curator.utils.PathUtils.validatePath(PathUtils.java:37)
        at org.apache.curator.utils.ZKPaths.fixForNamespace(ZKPaths.java:105)
        at org.apache.curator.framework.imps.NamespaceImpl.fixForNamespace(NamespaceImpl.java:104)
        at org.apache.curator.framework.imps.CuratorFrameworkImpl.fixForNamespace(CuratorFrameworkImpl.java:594)
        at org.apache.curator.framework.imps.GetChildrenBuilderImpl.forPath(GetChildrenBuilderImpl.java:198)
        at org.apache.curator.framework.imps.GetChildrenBuilderImpl.forPath(GetChildrenBuilderImpl.java:40)
        at com.alibaba.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient$CuratorWatcherImpl.process(CuratorZookeeperClient.java:131)
        at org.apache.curator.framework.imps.NamespaceWatcher.process(NamespaceWatcher.java:68)
        at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:530)
        at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:505)

Two 、Exception in thread “main” com.aliyuncs.exceptions.ClientException:

"C:\Program Files\Java\jdk1.8.0_161\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA 2018.3.5\lib\idea_rt.jar=58742:D:\Program Files\JetBrains\IntelliJ IDEA 2018.3.5\bin" -Dfile.encoding=GBK -classpath "C:\Program Files\Java\jdk1.8.0_161\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\rt.jar;E:\workspace\mchopin\target\classes;D:\repository\org\springframework\boot\spring-boot-starter-web\2.1.5.RELEASE\spring-boot-starter-web-2.1.5.RELEASE.jar;D:\repository\org\springframework\boot\spring-boot-starter\2.1.5.RELEASE\spring-boot-starter-2.1.5.RELEASE.jar;D:\repository\org\springframework\boot\spring-boot-starter-logging\2.1.5.RELEASE\spring-boot-starter-logging-2.1.5.RELEASE.jar;D:\repository\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;D:\repository\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;D:\repository\org\apache\logging\log4j\log4j-to-slf4j\2.11.2\log4j-to-slf4j-2.11.2.jar;D:\repository\org\apache\logging\log4j\log4j-api\2.11.2\log4j-api-2.11.2.jar;D:\repository\org\slf4j\jul-to-slf4j\1.7.26\jul-to-slf4j-1.7.26.jar;D:\repository\javax\annotation\javax.annotation-api\1.3.2\javax.annotation-api-1.3.2.jar;D:\repository\org\yaml\snakeyaml\1.23\snakeyaml-1.23.jar;D:\repository\org\springframework\boot\spring-boot-starter-json\2.1.5.RELEASE\spring-boot-starter-json-2.1.5.RELEASE.jar;D:\repository\com\fasterxml\jackson\core\jackson-databind\2.9.8\jackson-databind-2.9.8.jar;D:\repository\com\fasterxml\jackson\core\jackson-annotations\2.9.0\jackson-annotations-2.9.0.jar;D:\repository\com\fasterxml\jackson\core\jackson-core\2.9.8\jackson-core-2.9.8.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.9.8\jackson-datatype-jdk8-2.9.8.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.9.8\jackson-datatype-jsr310-2.9.8.jar;D:\repository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.9.8\jackson-module-parameter-names-2.9.8.jar;D:\repository\org\springframework\boot\spring-boot-starter-tomcat\2.1.5.RELEASE\spring-boot-starter-tomcat-2.1.5.RELEASE.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-core\9.0.19\tomcat-embed-core-9.0.19.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-el\9.0.19\tomcat-embed-el-9.0.19.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-websocket\9.0.19\tomcat-embed-websocket-9.0.19.jar;D:\repository\org\hibernate\validator\hibernate-validator\6.0.16.Final\hibernate-validator-6.0.16.Final.jar;D:\repository\javax\validation\validation-api\2.0.1.Final\validation-api-2.0.1.Final.jar;D:\repository\org\jboss\logging\jboss-logging\3.3.2.Final\jboss-logging-3.3.2.Final.jar;D:\repository\com\fasterxml\classmate\1.4.0\classmate-1.4.0.jar;D:\repository\org\slf4j\slf4j-api\1.7.26\slf4j-api-1.7.26.jar;D:\repository\org\springframework\spring-core\5.1.7.RELEASE\spring-core-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-jcl\5.1.7.RELEASE\spring-jcl-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-web\5.1.7.RELEASE\spring-web-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-beans\5.1.7.RELEASE\spring-beans-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-webmvc\5.1.7.RELEASE\spring-webmvc-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-aop\5.1.7.RELEASE\spring-aop-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-context\5.1.7.RELEASE\spring-context-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-expression\5.1.7.RELEASE\spring-expression-5.1.7.RELEASE.jar;D:\repository\org\mybatis\mybatis\3.5.1\mybatis-3.5.1.jar;D:\repository\org\springframework\boot\spring-boot-starter-jdbc\2.1.5.RELEASE\spring-boot-starter-jdbc-2.1.5.RELEASE.jar;D:\repository\com\zaxxer\HikariCP\3.2.0\HikariCP-3.2.0.jar;D:\repository\org\springframework\spring-jdbc\5.1.7.RELEASE\spring-jdbc-5.1.7.RELEASE.jar;D:\repository\org\springframework\spring-tx\5.1.7.RELEASE\spring-tx-5.1.7.RELEASE.jar;D:\repository\org\mybatis\spring\boot\mybatis-spring-boot-starter\2.0.1\mybatis-spring-boot-starter-2.0.1.jar;D:\repository\org\mybatis\spring\boot\mybatis-spring-boot-autoconfigure\2.0.1\mybatis-spring-boot-autoconfigure-2.0.1.jar;D:\repository\org\mybatis\mybatis-spring\2.0.1\mybatis-spring-2.0.1.jar;D:\repository\mysql\mysql-connector-java\5.1.46\mysql-connector-java-5.1.46.jar;D:\repository\org\springframework\boot\spring-boot-devtools\2.1.5.RELEASE\spring-boot-devtools-2.1.5.RELEASE.jar;D:\repository\org\springframework\boot\spring-boot\2.1.5.RELEASE\spring-boot-2.1.5.RELEASE.jar;D:\repository\org\springframework\boot\spring-boot-autoconfigure\2.1.5.RELEASE\spring-boot-autoconfigure-2.1.5.RELEASE.jar;D:\repository\com\aliyun\aliyun-java-sdk-core\4.0.6\aliyun-java-sdk-core-4.0.6.jar;D:\repository\com\google\code\gson\gson\2.8.5\gson-2.8.5.jar;D:\repository\org\apache\httpcomponents\httpclient\4.5.8\httpclient-4.5.8.jar;D:\repository\org\apache\httpcomponents\httpcore\4.4.11\httpcore-4.4.11.jar;D:\repository\commons-codec\commons-codec\1.11\commons-codec-1.11.jar;D:\repository\javax\xml\bind\jaxb-api\2.3.1\jaxb-api-2.3.1.jar;D:\repository\javax\activation\javax.activation-api\1.2.0\javax.activation-api-1.2.0.jar;D:\repository\com\sun\xml\bind\jaxb-core\2.1.14\jaxb-core-2.1.14.jar;D:\repository\com\sun\xml\bind\jaxb-impl\2.1\jaxb-impl-2.1.jar;D:\repository\javax\activation\activation\1.1.1\activation-1.1.1.jar;D:\repository\com\aliyun\aliyun-java-sdk-dysmsapi\1.1.0\aliyun-java-sdk-dysmsapi-1.1.0.jar;D:\repository\com\alibaba\fastjson\1.2.47\fastjson-1.2.47.jar" com.xxp.mchopin.util.SmsDemo
Exception in thread "main" com.aliyuncs.exceptions.ClientException: MissingAccessKeyId : AccessKeyId is mandatory for this action. RequestId : F58F1F9E-8D3F-44A3-A64E-E6B4BCB51BA1
	at com.aliyuncs.DefaultAcsClient.parseAcsResponse(DefaultAcsClient.java:230)
	at com.aliyuncs.DefaultAcsClient.getAcsResponse(DefaultAcsClient.java:134)
	at com.xxp.mchopin.util.SmsDemo.sendSms(SmsDemo.java:47)
	at com.xxp.mchopin.util.SmsDemo.main(SmsDemo.java:70)

Process finished with exit code 1

3、 ... and 、java.io.IOException: Broken pipe

know broken pipe
pipe It means pipe , Inside the pipeline is the data flow , Usually data read from a file or network socket . When the pipe suddenly closes from the other end , Sudden interruption of data will occur , That is broken. For the file File Come on , This may be because the file is installed on a disconnected CD or on a remote network . about socket Come on , It may be that the network is unplugged or the process at the other end crashes . stay Java in , There is no specific BrokenPipeException. Include such errors in another exception , for example java.io.IOException:Broken pipe

solve the problem
In fact, when the exception occurs , For the server , Not much impact . This error may be caused by the sudden termination of the process by a client . But in order to make the program beautiful 、 grace , Or catch the exception in the right place , And deal with it . Another possibility is that the code in the program takes too long to execute , The user waited too long , Will forcibly stop the process . In this case, we need to analyze log What is unusual in the interim report is where it often happens , Optimize the code reasonably , Improve the running speed of code , In order to fundamentally avoid the recurrence of such problems .

Four 、java.net.MalformedURLException

URL url = new URL(param);

When building objects , Participation is null, Lead to URL switch views . Before entering the parameter , Carry out non null Judge , This exception can be avoided .

5、 ... and 、org.springframework.web.HttpMediaTypeNotSupportedException

6、 ... and 、java.lang.Exception: Test class should have exactly one public zero-argument constructor

7、 ... and 、java.time.format.DateTimeParseException

Exception in thread "main" java.time.format.DateTimeParseException: Text '2008-8-08 00:00:00' could not be parsed at index 5
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1949)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at com.yikesong.core.domain.money.model.finance.FinanceService.getInstants(FinanceService.java:179)
    at com.yikesong.core.domain.money.model.finance.FinanceService.main(FinanceService.java:167)

8、 ... and 、ResourceNotFoundException