java - Hibernate查询异常-6ren

java - Hibernate查询异常

转载作者：行者123 更新时间：2023-12-02 08:32:56

我有一个 hibernate 查询，我正在尝试开始工作，但不断收到异常，并且堆栈跟踪不太有用。我在抛出异常之前包括了代码、堆栈跟踪和 hibernate 聊天。如果您需要我包含 MessageTarget 和 GrpExclusion 的实体类，请在评论中告诉我，我将添加它们。

public List<MessageTarget> findMessageTargets(int age, String gender, String businessCode, String groupId, String systemCode) {
    Session session = getHibernateTemplate().getSessionFactory().openSession();
    List<MessageTarget> results = new ArrayList<MessageTarget>();
    try {
        String hSql = "from MessageTarget mt where " +
                        "not exists (select GrpExclusion where grp_no = ?) and " +
                        "(trgt_gndr_cd = 'A' or trgt_gndr_cd = ?) and " +
                        "sys_src_cd = ? and " +
                        "bampi_busn_sgmnt_cd = ? and " +
                        "trgt_low_age <= ? and " +
                        "trgt_high_age >= ? and " +
                        "(effectiveDate is null or effectiveDate <= ?) and " +
                        "(termDate is null or termDate >= ?)";

        results = session.createQuery(hSql)
                                        .setParameter(0, groupId)
                                        .setParameter(1, gender)
                                        .setParameter(2, systemCode)
                                        .setParameter(3, businessCode)
                                        .setParameter(4, age)
                                        .setParameter(5, age)
                                        .setParameter(6, new Date())
                                        .setParameter(7, new Date())
                                        .list();
    } catch (Exception e) {
        System.err.println(e.getMessage());
        e.printStackTrace();

    } finally {
      session.close();
    }
    return results;
}

这是堆栈跟踪。

[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R java.lang.NullPointerException
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.util.SessionFactoryHelper.findSQLFunction(SessionFactoryHelper.java:365)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.tree.IdentNode.getDataType(IdentNode.java:289)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:165)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.HqlSqlWalker.useSelectClause(HqlSqlWalker.java:831)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.HqlSqlWalker.processQuery(HqlSqlWalker.java:619)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:672)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.collectionFunctionOrSubselect(HqlSqlBaseWalker.java:4465)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.comparisonExpr(HqlSqlBaseWalker.java:4165)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1864)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1839)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1789)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.whereClause(HqlSqlBaseWalker.java:818)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:604)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:288)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:231)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:254)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:185)
[5/6/10 15:05:21:041 EDT] 00000017 SystemErr     R  at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:94)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:135)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1651)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.bcbst.bamp.ws.dao.MessageTargetDAOImpl.findMessageTargets(MessageTargetDAOImpl.java:30)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.bcbst.bamp.ws.common.AlertReminder.findMessageTargets(AlertReminder.java:22)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at java.lang.reflect.Method.invoke(Method.java:599)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.jaxws.server.dispatcher.JavaDispatcher.invokeTargetOperation(JavaDispatcher.java:81)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.jaxws.server.dispatcher.JavaBeanDispatcher.invoke(JavaBeanDispatcher.java:98)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.jaxws.server.EndpointController.invoke(EndpointController.java:109)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.jaxws.server.JAXWSMessageReceiver.receive(JAXWSMessageReceiver.java:159)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:188)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:275)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.websvcs.transport.http.WASAxis2Servlet.doPost(WASAxis2Servlet.java:1389)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at javax.servlet.http.HttpServlet.service(HttpServlet.java:738)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at javax.servlet.http.HttpServlet.service(HttpServlet.java:831)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1536)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:829)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:458)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:175)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3742)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:276)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:929)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1583)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:178)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:455)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:384)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:272)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
[5/6/10 15:05:21:057 EDT] 00000017 SystemErr     R  at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1550)

这是 hibernate 的喋喋不休。

[5/6/10 15:05:20:651 EDT] 00000017 XmlBeanDefini I org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions Loading XML bean definitions from class path resource [beans.xml]
[5/6/10 15:05:20:823 EDT] 00000017 Configuration I org.slf4j.impl.JCLLoggerAdapter info configuring from url: file:/C:/workspaces/bampi/AlertReminderWS/WebContent/WEB-INF/classes/hibernate.cfg.xml
[5/6/10 15:05:20:838 EDT] 00000017 Configuration I org.slf4j.impl.JCLLoggerAdapter info Configured SessionFactory: java:hibernate/Alert/SessionFactory1.0.3
[5/6/10 15:05:20:838 EDT] 00000017 AnnotationBin I org.hibernate.cfg.AnnotationBinder bindClass Binding entity from annotated class: com.bcbst.bamp.ws.model.MessageTarget
[5/6/10 15:05:20:838 EDT] 00000017 EntityBinder  I org.hibernate.cfg.annotations.EntityBinder bindTable Bind entity com.bcbst.bamp.ws.model.MessageTarget on table MessageTarget
[5/6/10 15:05:20:854 EDT] 00000017 AnnotationBin I org.hibernate.cfg.AnnotationBinder bindClass Binding entity from annotated class: com.bcbst.bamp.ws.model.GrpExclusion
[5/6/10 15:05:20:854 EDT] 00000017 EntityBinder  I org.hibernate.cfg.annotations.EntityBinder bindTable Bind entity com.bcbst.bamp.ws.model.GrpExclusion on table GrpExclusion
[5/6/10 15:05:20:854 EDT] 00000017 CollectionBin I org.hibernate.cfg.annotations.CollectionBinder bindOneToManySecondPass Mapping collection: com.bcbst.bamp.ws.model.MessageTarget.exclusions -> GrpExclusion
[5/6/10 15:05:20:885 EDT] 00000017 AnnotationSes I org.springframework.orm.hibernate3.LocalSessionFactoryBean buildSessionFactory Building new Hibernate SessionFactory
[5/6/10 15:05:20:901 EDT] 00000017 ConnectionPro I org.slf4j.impl.JCLLoggerAdapter info Initializing connection provider: org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider
[5/6/10 15:05:20:901 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info RDBMS: Microsoft SQL Server, version: 9.00.4035
[5/6/10 15:05:20:901 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info JDBC driver: Microsoft SQL Server 2005 JDBC Driver, version: 1.2.2828.100
[5/6/10 15:05:20:901 EDT] 00000017 Dialect       I org.slf4j.impl.JCLLoggerAdapter info Using dialect: org.hibernate.dialect.SQLServerDialect
[5/6/10 15:05:20:916 EDT] 00000017 TransactionFa I org.slf4j.impl.JCLLoggerAdapter info Transaction strategy: org.springframework.orm.hibernate3.SpringTransactionFactory
[5/6/10 15:05:20:916 EDT] 00000017 TransactionMa I org.slf4j.impl.JCLLoggerAdapter info No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Automatic flush during beforeCompletion(): disabled
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Automatic session close at end of transaction: disabled
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Scrollable result sets: enabled
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info JDBC3 getGeneratedKeys(): enabled
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Connection release mode: auto
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Default batch fetch size: 1
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Generate SQL with comments: disabled
[5/6/10 15:05:20:916 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Order SQL updates by primary key: disabled
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Order SQL inserts for batching: disabled
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
[5/6/10 15:05:20:932 EDT] 00000017 ASTQueryTrans I org.slf4j.impl.JCLLoggerAdapter info Using ASTQueryTranslatorFactory
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Query language substitutions: {}
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info JPA-QL strict compliance: disabled
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Second-level cache: enabled
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Query cache: disabled
[5/6/10 15:05:20:932 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge
[5/6/10 15:05:20:932 EDT] 00000017 RegionFactory I org.slf4j.impl.JCLLoggerAdapter info Cache provider: org.hibernate.cache.NoCacheProvider
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Optimize cache for minimal puts: disabled
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Structured second-level cache entries: disabled
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Statistics: disabled
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Deleted entity synthetic identifier rollback: disabled
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Default entity-mode: pojo
[5/6/10 15:05:20:948 EDT] 00000017 SettingsFacto I org.slf4j.impl.JCLLoggerAdapter info Named query checking : enabled
[5/6/10 15:05:20:979 EDT] 00000017 SessionFactor I org.slf4j.impl.JCLLoggerAdapter info building session factory
[5/6/10 15:05:21:010 EDT] 00000017 SessionFactor I org.slf4j.impl.JCLLoggerAdapter info Factory name: java:hibernate/Alert/SessionFactory1.0.3
[5/6/10 15:05:21:010 EDT] 00000017 NamingHelper  I org.slf4j.impl.JCLLoggerAdapter info JNDI InitialContext properties:{}
[5/6/10 15:05:21:010 EDT] 00000017 NamingHelper  I org.slf4j.impl.JCLLoggerAdapter info Creating subcontext: java:hibernate
[5/6/10 15:05:21:010 EDT] 00000017 NamingHelper  I org.slf4j.impl.JCLLoggerAdapter info Creating subcontext: Alert
[5/6/10 15:05:21:010 EDT] 00000017 SessionFactor I org.slf4j.impl.JCLLoggerAdapter info Bound factory to JNDI name: java:hibernate/Alert/SessionFactory1.0.3
[5/6/10 15:05:21:026 EDT] 00000017 SessionFactor W org.slf4j.impl.JCLLoggerAdapter warn InitialContext did not implement EventContext
[5/6/10 15:05:21:041 EDT] 00000017 PARSER        E org.slf4j.impl.JCLLoggerAdapter error <AST>:0:0: unexpected end of subtree

最佳答案

您没有正确编写 HQL。我建议阅读HQL chapter来自文档。

我认为您的查询有一些错误:

您的子选择不是有效的 HQL 查询。类似 (from GroupExclusion ge where groupNumber = ?) 的内容可能更接近您想要的。
列名称应与其 Java getter 名称匹配，而不是与数据库列名称匹配。
您应该在finally block 中关闭HibernateSession:
Session session = getHibernateTemplate().getSessionFactory().openSession();尝试 { ...} 最后 { session .关闭();}

关于java - Hibernate查询异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/2783774/

文章推荐： java - 端口绑定(bind) "problem"与 Eclipse、Java 和 Windows

文章推荐： java - 包含jsp后如何关闭输出流

文章推荐： java - 如何以编程方式从Java源代码中的类中提取方法体？

文章推荐： java - 如何开发完整的软件套件/平台？

java - Java 方法如何检索属于该特定方法的方法对象？ ( java )
我正在编写一个具有以下签名的 Java 方法。 void Logger(Method method, Object[] args); 如果一个方法(例如 ABC() )调用此方法 Logger，它应该
java - (Java) Java 找不到我的图像文件
我是 Java 新手。我的问题是我的 Java 程序找不到我试图用作的图像文件一个 JButton。 (目前这段代码什么也没做，因为我只是得到了想要的外观第一的)。这是我的主课代码: packag
java - java Java 有手动垃圾回收吗？
好的，今天我在接受采访，我已经编写 Java 代码多年了。采访中说“Java 垃圾收集是一个棘手的问题，我有几个 friend 一直在努力弄清楚。你在这方面做得怎么样？”。她是想骗我吗？还是我的一生都
java - Java 之谜 - Java
我的 friend 给了我一个谜语让我解开。它是这样的: There are 100 people. Each one of them, in his turn, does the following
java - Java 字节码是否兼容不同版本的 Java？
如果我将使用 Java 5 代码的应用程序编译成字节码，生成的 .class 文件是否能够在 Java 1.4 下运行？如果后者可以工作并且我正在尝试在我的 Java 1.4 应用程序中使用 Jav
java - Java 缺少无符号原始类型是 Java 平台的特征还是 Java 语言的特征？
有关于why Java doesn't support unsigned types的问题以及一些关于处理无符号类型的问题。我做了一些搜索，似乎 Scala 也不支持无符号数据类型。限制是Java和S
java - Java 7 的 Java 字节码可以在其他版本的 Java 中工作吗
我只是想知道在一个 java 版本中生成的字节码是否可以在其他 java 版本上运行最佳答案通常，字节码无需修改即可在较新版本的 Java 上运行。它不会在旧版本上运行，除非您使用特殊参数 (
java -cp 。 test.java 与 java test.java
我有一个关于在命令提示符下执行 java 程序的基本问题。在某些机器上我们需要指定 -cp 。 (类路径)同时执行java程序 (test为java文件名与.class文件存在于同一目录下) jav
java - 使用 Java (Java EE/Java SE) 的数据库应用程序设计模式
我已经阅读 StackOverflow 有一段时间了，现在我才鼓起勇气提出问题。我今年 20 岁，目前在我的家乡(罗马尼亚克卢日-纳波卡)就读 IT 大学。足以介绍:D。基本上，我有一家提供簿记应用
java - Java 中的解析可在 Java 中访问
我有 public JSONObject parseXML(String xml) { JSONObject jsonObject = XML.toJSONObject(xml); r
java - Java 中的解释性语言以及对 Java 方法的调用
我已经在 Java 中实现了带有动态类型的简单解释语言。不幸的是我遇到了以下问题。测试时如下代码: def main() { def ks = Map[[1, 2]].keySet()
java - java 序数 - Java I 类
一直提示输入 1 到 10 的数字 - 结果应将 st、rd、th 和 nd 添加到数字中。编写一个程序，提示用户输入 1 到 10 之间的任意整数，然后以序数形式显示该整数并附加后缀。 public
java - 如何从 Java 执行 Java？
我有这个 DownloadFile.java 并按预期下载该文件: import java.io.*; import java.net.URL; public class DownloadFile {
java - 延迟不适用于 java gui(java)
我想在 GUI 上添加延迟。我放置了 2 个 for 循环，然后重新绘制了一个标签，但这 2 个 for 循环一个接一个地执行，并且标签被重新绘制到最后一个。我能做什么？ for(int i=0;
java - Java 类中的硬编码 Java 列表
我正在对对象 Student 的列表项进行一些测试，但是我更喜欢在 java 类对象中创建硬编码列表，然后从那里提取数据，而不是连接到数据库并在结果集中选择记录。然而，自从我这样做以来已经很长时间了，
java - java 幕后对象创建(java 对象实例化)
我知道对象创建分为三个部分: 声明实例化初始化 classA{} classB extends classA{} classA obj = new classB(1,1); 实例化它必须使用
java - 车辆跟踪系统[java/Java EE]
我有兴趣使用 GPRS 构建车辆跟踪系统。但是，我有一些问题要问以前做过此操作的人: GPRS 是最好的技术吗？人们意识到任何问题吗？我计划使用 Java/Java EE - 有更好的技术吗？如果
java - 逆数组(Java)//逆数组(Java)
我可以通过递归方法反转数组，例如:数组={1,2,3,4,5} 数组结果={5,4,3,2,1}但我的结果是相同的数组，我不知道为什么，请帮助我。 public class Recursion { p
java - Java/Java EE 的构建和集成环境
有这样的标准方式吗？包括 Java源代码-测试代码- Ant 或 Maven联合单元持续集成(可能是巡航控制)ClearCase 版本控制工具部署到应用服务器最后我希望有一个自动构建和集成环境。
java - 我将如何从 java 程序打印文本？ ( java )
我什至不知道这是否可能，我非常怀疑它是否可能，但如果可以，您能告诉我怎么做吗？我只是想知道如何从打印机打印一些文本。有什么想法吗？最佳答案这里有更简单的事情。 import javax.swin

行者123

个人简介

我是一名优秀的程序员,十分优秀！

作者热门文章

滴滴打车优惠券免费领取

全站热门文章

首页

博学

6Ren·AI

商城

java - Hibernate查询异常