无法对java类中的非静态字段进行静态引用

时间：2015-12-09 10:13:26

标签： java 

public class College {
   public String collegename;
   public String branch;
   public String username;
   public String password;
 public College(String college,String branch,String user, String pass)
 {
 College.collegename = college;
 College.branch= branch;
 College.username= user;
 College.password= pass;
 }
}

这是我的类，并且正在出现的错误是无法对非静态字段进行静态引用。请告诉我这是什么问题，让我知道如何解决它。

先谢谢。

3 个答案:

答案 0 :(得分：1)

您正在向构造函数传递错误的实例：您必须将类'实例称为“this”。 正确的语法：

Caused by: org.hibernate.exception.SQLGrammarException: could not prepare statement
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:80) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:196) ~[hibernate-core-4.3.9.   Final.jar:4.3.9.Final]
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:160) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1885) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1862) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1839) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.doQuery(Loader.java:910) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:355) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2554) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2540) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2370) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.Loader.list(Loader.java:2365) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:497) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:236) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1300) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.jpa.internal.QueryImpl.list(QueryImpl.java:573) ~[hibernate-entitymanager-4.3.9.Final.jar:4.3.9.Final]
    at org.hibernate.jpa.internal.QueryImpl.getResultList(QueryImpl.java:449) ~[hibernate-entitymanager-4.3.9.Final.jar:4.3.9.Final]
at org.hibernate.jpa.criteria.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:67) ~[hibernate-entitymanager-4.3.9.Final. jar:4.3.9.Final]
at org.springframework.data.jpa.repository.query.JpaQueryExecution$CollectionExecution.doExecute(JpaQueryExecution.java:114) ~[spring-data-jpa-1.9.1.RELEASE.jar:na ]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:78) ~[spring-data-jpa-1.9.1.RELEASE.jar:na]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:100) ~[spring-data-jpa-1.9.1.RELEASE.jar:na]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:91) ~[spring-data-jpa-1.9.1.RELEASE.jar:na]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:462) ~[spring-   data-commons-1.11.1.RELEASE.jar:na]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:440) ~[spring-data -commons-1.11.1.RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.2.2.RELEASE.jar:4.2.2.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:61) ~[spring-data-commons-1.11.1.  RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.2.2.RELEASE.jar:4.2.2.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) ~[spring-tx-4.2.2.RELEASE.jar:4.2.2.  RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) ~[spring-tx-4.2.2.RELEASE.jar:4. 2.2.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.2.2.RELEASE.jar:4.2.2.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.2.2.RELEASE.jar:4.2.2.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136) ~[spring-tx-4.2.2.RELEASE .jar:4.2.2.RELEASE]
    ... 112 common frames omitted
Caused by: java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: MYCLAS0_.VALIDATE
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.jdbc.JDBCPreparedStatement.<init>(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.jdbc.JDBCConnection.prepareStatement(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at com.zaxxer.hikari.proxy.ConnectionProxy.prepareStatement(ConnectionProxy.java:280) ~[HikariCP-java6-2.2.5.jar:na]
    at com.zaxxer.hikari.proxy.ConnectionJavassistProxy.prepareStatement(ConnectionJavassistProxy.java) ~[HikariCP-java6-2.2.5.jar:na]
    at sun.reflect.GeneratedMethodAccessor112.invoke(Unknown Source) ~[na:na]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
    at net.bull.javamelody.JdbcWrapper$ConnectionInvocationHandler.invoke(JdbcWrapper.java:189) ~[javamelody-core-1.57.0.jar:1.57.0]
    at net.bull.javamelody.JdbcWrapper$DelegatingInvocationHandler.invoke(JdbcWrapper.java:286) ~[javamelody-core-1.57.0.jar:1.57.0]
    at com.sun.proxy.$Proxy44.prepareStatement(Unknown Source) ~[na:na]
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:162) ~[hibernate-core-4.3.9.Final.jar:4.3.9.Final]
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:186) ~[hibernate-core-4.3.9.   Final.jar:4.3.9.Final]
    ... 144 common frames omitted
Caused by: org.hsqldb.HsqlException: user lacks privilege or object not found: MYCLAS0_.VALIDATE
    at org.hsqldb.error.Error.error(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.error.Error.error(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.ExpressionColumn.checkColumnsResolved(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.QueryExpression.resolve(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.ParserCommand.compilePart(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.ParserCommand.compileStatement(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.Session.compileStatement(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.StatementManager.compile(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    at org.hsqldb.Session.execute(Unknown Source) ~[hsqldb-2.3.3.jar:2.3.3]
    ... 156 common frames omitted

答案 1 :(得分：1)

您正在声明类级别变量并将其用作静态成员。 试试

public class College {
   public String collegename;
   public String branch;
   public String username;
   public String password;
 public college(String college,String branch,String user, String pass)
 {
     this.collegename = college;
     this.branch= branch;
     this.username= user;
     this.password= pass;
 }
}

this关键字用于引用类变量。

修改

如果您想使用评论中提到的内容。

public class College {
  String collegename;
  String branch;
  String username;
  String password;
  private static College instance = null;
  protected College() {
      // Exists only to defeat instantiation.
   }
  public static College getInstance() {
      if(instance == null) {
         instance = new College();
      }
      return instance;
   }
  public void SetData(String collegeName, String branch, String userName, String password)
  {
         this.collegename = collegeName;
         this.branch= branch;
         this.username= userName;
         this.password= password;
  }

  public String GetCollegeName()
  {
    return this.collegename;
  }
  // So on...
}

将所有数据设置在任何类别的任何位置，例如

College.getInstance().SetData("abcCollege","abcBranch","username","password");

在另一个类中使用它，例如

ArrayList<NameValuePair>dataToSend = new ArrayList<>(); dataToSend.add(new BasicNameValuePair("collegename", College.getInstance().GetCollegeName()));

或者只是制作学院的实例。

College college = new College("abcCollege","abcBranch","username","password")
ArrayList<NameValuePair>dataToSend = new ArrayList<>(); dataToSend.add(new BasicNameValuePair("collegename", college. collegename));

虽然我不了解Java，但它应该是这样的。

答案 2 :(得分：0)

将构造函数中'College'的所有引用替换为'this'。 'this'关键字引用当前对象，而使用类名'College'直接引用类的静态访问。

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