java - Long.parseLong 给出 java.lang.NumberFormatException

Question

所以我尝试了很多东西，但我无法解决这个问题。 Service 类中的 id 数据类型为 long。我试图将 serviceAuth 转换为 long，但它抛出一个 java.lang.NumberFormatException。我该如何解决这个问题？

String[] serviceList = getUser.serviceList.split(",");

for(String serviceAuth: serviceList) {
    Long temp = Long.parseLong(serviceAuth.toString());
    Criteria ctr = sessionFactory.getCurrentSession().createCriteria(Service.class)
                        .add(Restrictions.eq("id",temp));
}

serviceList 看起来像这样 5,18,19。它是从 csv 文件加载的。

当我在 for 循环中打印值时，它看起来像这样:

1
2
14
15

错误报告:

 java.lang.NumberFormatException: For input string: ""
    java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    java.lang.Long.parseLong(Long.java:601)
    java.lang.Long.parseLong(Long.java:631)
    org.x.y.gateway.MainController.getUsers(MainController.java:1433)
    org.x.y.gateway.MainController$$FastClassBySpringCGLIB$$6e5db2d9.invoke(<generated>)
    org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:266)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
    org.x.y.gateway.MainController$$EnhancerBySpringCGLIB$$149bedb6.getUsers(<generated>)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:483)
    org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.x.y.gateway.CrossOriginRequest.doFilter(CrossOriginRequest.java:18)

Answer 1

您的问题是 split() 创建的字符串之一为空或包含空格，例如

package de.scrum_master.app;

public class Application {
    public static void main(String[] args) {
        String[] serviceList = ",15,18,19".split(",");
        for (String serviceAuth : serviceList) {
            Long temp = Long.parseLong(serviceAuth.toString());
            System.out.println(temp);
        }
    }
}

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(Unknown Source)
    at java.lang.Long.parseLong(Unknown Source)
    at java.lang.Long.parseLong(Unknown Source)
    at de.scrum_master.app.Application.main(Application.java:7)

---

更新:如何解决问题

你应该做两件事:

• 使拆分正则表达式对前导和尾随空格更加稳定。
• 跳过循环中仍可能出现在数组开头的 "" 的值。

package de.scrum_master.app;

public class Application {
    public static void main(String[] args) {
        String[] serviceList = " , 15 , 18 , 19, ".split("[\\s,]+");
        for (String serviceAuth : serviceList) {
            if ("".equals(serviceAuth))
                continue;
            Long temp = Long.parseLong(serviceAuth.toString());
            System.out.println(temp);
        }
    }
}

15
18
19