尝试将新的List对象添加到预定义的List对象时出现错误

我正在使用Java 8在Spring Boot版本2上工作，当我尝试在“ createTopic”方法中将新的List对象添加到预定义的List对象（即topicList）时，出现错误。

**

TopicService.java

**

public class TopicService {

    private List<TopicObject>  topicList = Arrays.asList(
            new TopicObject("Java", "Java Course", "Spring boot in java"),
            new TopicObject("Maths", "Mathematics class","12th maths")
    );



    public String createTopic(TopicObject topicObj){

         topicList.add(new TopicObject("Java1", "Java Course1", "Spring boot in java1"));

        return "Request successful"  ;
    }
}

**

TopicObject.java

**

package io.javabrains.springBootStarter.controller;

import com.fasterxml.jackson.annotation.JsonProperty;

public class TopicObject {

    @JsonProperty("id")
    private String id;

    @JsonProperty("name")
    private String name;

    @JsonProperty("description")
    private String description;

    public TopicObject() {
    }

    public TopicObject(String id, String name, String description) {
        this.id = id;
        this.name = name;
        this.description = description;
    }


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

}

**

错误

**

2020-04-15 19：52：27.172错误15312-[nio-8080-exec-2] oaccC [。[。[/]。[dispatcherServlet]：Servlet [dispatcherServlet]的Servlet.service（）路径[]引发异常[请求处理失败；嵌套异常是java.lang.UnsupportedOperationException]，其根本原因是

java.lang.UnsupportedOperationException：在java.util.AbstractList.add（AbstractList.java:148）为null [java：util.AbstractList.add（AbstractList.java:108）〜[na：1.8.0_221]〜[na：1.8 .0_221]在io.javabrains.springBootStarter.Service.TopicService.createTopic（TopicService.java:29）〜[classes /：na]在io.javabrains.springBootStarter.controller.TopicController.createTopic（TopicController.java:31）〜[ classes /：na]在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）〜[na：1.8.0_221]在sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）〜[na：1.8.0_221] .reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）〜[na：1.8.0_221]在java.lang.reflect.Method.invoke（Method.java:498）〜[na：1.8.0_221]在org.springframework .web.method.support.InvocableHandlerMethod.doInvoke（InvocableHandlerMethod.java：209）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE]在org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest（InvocableHandlerMethod.java:136）〜[spring-web-5.0 .13.RELEASE.jar：5.0.13.RELEASE]，位于org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle（ServletInvocableHandlerMethod.java:102）〜[spring-webmvc-5.0.13.RELEASE。 jar：5.0.13.RELEASE]位于org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod（RequestMappingHandlerAdapter.java:894）〜[spring-webmvc-5.0.13.RELEASE.jar：5.0.13 .RELEASE]在org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal（RequestMappingHandlerAdapter.java:800）〜[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE]在org .springframework.web.servlet.mvc.method。AbstractHandlerMethodAdapter.handle（AbstractHandlerMethodAdapter.java:87）〜[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE]在org.springframework.web.servlet.DispatcherServlet.doDispatch（DispatcherServlet.java:991）〜 org.springframework.web.servlet.DispatcherServlet.doService（DispatcherServlet.java:925）上的[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE]〜[spring-webmvc-5.0.13.RELEASE。 org.springframework.web.servlet.FrameworkServlet.processRequest（FrameworkServlet.java:981）处的jar：5.0.13.RELEASE] org.org的[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE]。 springframework.web.servlet.FrameworkServlet.doPost（FrameworkServlet.java:884）〜[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE]在javax.servlet.http.HttpServlet.service（HttpServlet.java ：661）〜[tomcat-embed-core-8.5.39.jar：8.5.39]，网址为org.springframework.web.servlet.FrameworkServlet。service（FrameworkServlet.java:858）〜[spring-webmvc-5.0.13.RELEASE.jar：5.0.13.RELEASE] at javax.servlet.http.HttpServlet.service（HttpServlet.java:742）〜[tomcat嵌入-core-8.5.39.jar：8.5.39]，位于org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:231）〜[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.tomcat.websocket.server.WsFilter处的org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39] doFilter（WsFilter.java:52）〜[tomcat-embed-websocket-8.5.39.jar：8.5.39] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:193）〜[tomcat-embed -core-8.5.39.jar：8.5.39]，位于org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39]在组织。springframework.web.filter.RequestContextFilter.doFilterInternal（RequestContextFilter.java:99）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter .java：107）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE]在org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:193）〜[tomcat-embed-内核8.5.39.jar：8.5.39]位于org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39] org.springframework.web.filter.OncePerRequestFilter.doFilter上的org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal（HttpPutFormContentFilter.java:109）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE] （OncePerRequestFilter.java:107）〜[spring-web-5.0.13.RELEASE.jar：5.0.13。RELEASE]位于org.apache.catalina.core.ApplicationFilterChain的org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:193）〜[tomcat-embed-core-8.5.39.jar：8.5.39]。 doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39]在org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal（HiddenHttpMethodFilter.java:93）〜[spring-web -5.0.13.RELEASE.jar：5.0.13.RELEASE]，位于org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter.java:107）〜[spring-web-5.0.13.RELEASE.jar：5.0。 13.RELEASE]位于org.apache.catalina.core的org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:193）〜[tomcat-embed-core-8.5.39.jar：8.5.39]。组织中的ApplicationFilterChain.doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39]。springorgwork.web.filter.CharacterEncodingFilter.doFilterInternal（CharacterEncodingFilter.java:200）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter（OncePerRequestFilter .java：107）〜[spring-web-5.0.13.RELEASE.jar：5.0.13.RELEASE]在org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:193）〜[tomcat-embed-内核8.5.39.jar：8.5.39]位于org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:166）〜[tomcat-embed-core-8.5.39.jar：8.5.39] org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve的org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:199）〜[tomcat-embed-core-8.5.39.jar：8.5.39] .java：96）[tomcat-embed-core-8.5.39.jar：8.5.39]，网址为org.apache.catalina.authenticator。AuthenticatorBase.invoke（AuthenticatorBase.java:493）[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:137）[tomcat嵌入-core-8.5.39.jar：8.5.39]，位于org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:81）[tomcat-embed-core-8.5.39.jar：8.5.39]，位于org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter。上的org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:87）[tomcat-embed-core-8.5.39.jar：8.5.39] java：343）[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.coyote.http11.Http11Processor.service（Http11Processor.java:798）[tomcat-embed-core-8.5.39 .jar：8.5.39]，位于org.apache.coyote.AbstractProcessorLight.process（AbstractProcessorLight.java:66）[tomcat-embed-core-8.5.39.jar：8.5.39]，位于org.apache.coyote。org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java：上的AbstractProtocol $ ConnectionHandler.process（AbstractProtocol.java:806）[tomcat-embed-core-8.5.39.jar：8.5.39] 1498）[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.tomcat.util.net.SocketProcessorBase.run（SocketProcessorBase.java:49）[tomcat-embed-core-8.5.39 .jar：8.5.39]，位于java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1149）[na：1.8.0_221]，位于java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:624） [na：1.8.0_221]在org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）在Java的[tomcat-embed-core-8.5.39.jar：8.5.39]。 lang.Thread.run（Thread.java:748）[na：1.8.0_221]NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1498）[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.tomcat.util.net.SocketProcessorBase.run（SocketProcessorBase.java:49） [tomcat-embed-core-8.5.39.jar：8.5.39]在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1149）[na：1.8.0_221]在java.util.concurrent.ThreadPoolExecutor $ org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）上的Worker.run（ThreadPoolExecutor.java:624）[na：1.8.0_221] [tomcat-embed-core-8.5.39 .jar：8.5.39]，位于java.lang.Thread.run（Thread.java:748）[na：1.8.0_221]NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1498）[tomcat-embed-core-8.5.39.jar：8.5.39]在org.apache.tomcat.util.net.SocketProcessorBase.run（SocketProcessorBase.java:49） [tomcat-embed-core-8.5.39.jar：8.5.39]在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1149）[na：1.8.0_221]在java.util.concurrent.ThreadPoolExecutor $ org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）上的Worker.run（ThreadPoolExecutor.java:624）[na：1.8.0_221] [tomcat-embed-core-8.5.39 .jar：8.5.39]，位于java.lang.Thread.run（Thread.java:748）[na：1.8.0_221]1149）[na：1.8.0_221]在java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:624）[na：1.8.0_221]在org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable中。在java.lang.Thread.run（Thread.java:748）上运行（TaskThread.java:61）[tomcat-embed-core-8.5.39.jar：8.5.39] [na：1.8.0_221]1149）[na：1.8.0_221]在java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:624）[na：1.8.0_221]在org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable中。在java.lang.Thread.run（Thread.java:748）上运行（TaskThread.java:61）[tomcat-embed-core-8.5.39.jar：8.5.39] [na：1.8.0_221]

>我不知道是否可以通过这种方式将新对象添加到“ topicList”中。有人可以帮忙吗？