你的代码运行环境没有包含log4j的包,因此代码默认使用了jdk中自带的同名包。要解决这个问题很简单,让你的程序使用独立的log4j的jar包就可以了。你可以上网搜索如何使用第三方jar包,网上很多描述。 如果你是在eclipse中运行的话,只要在project中加入lib文件夹,将log4j的相关jar包放入该目录,然后在eclipse中选择这些jar包后,点击右键菜单 "Build Path" -> "Add to Build Path"即可。
首先谢谢你,但是我加入了那个jar了仍然报那个错误,无语了 Exception in thread "main" java.lang.ExceptionInInitializerError at MTest.main(MTest.java:14) Caused by: com.sun.org.apache.commons.logging.LogConfigurationException: com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException) (Caused by com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException)) at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:543) at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:235) at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:209) at com.sun.org.apache.commons.logging.LogFactory.getLog(LogFactory.java:351) at com.sun.org.apache.commons.beanutils.BeanUtils.<clinit>(BeanUtils.java:111) ... 1 more Caused by: com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException) at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getLogConstructor(LogFactoryImpl.java:397) at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:529) ... 5 more Caused by: java.lang.NullPointerException at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getLogConstructor(LogFactoryImpl.java:374) ... 6 more
还是不行,我看了Exception in thread "main" java.lang.ExceptionInInitializerError 这个错误然后又报了空指针,我把import改成了java.lang.*错误变了 Exception in thread "main" java.lang.Error: Unresolved compilation problems: InvocationTargetException cannot be resolved to a type e cannot be resolved at MTest.main(MTest.java:32) 我import是这样的 import java.lang.*; import java.util.Iterator; import java.util.Map; import java.util.Set;import com.sun.org.apache.commons.beanutils.BeanUtils; 彻底无语了
如果你是在eclipse中运行的话,只要在project中加入lib文件夹,将log4j的相关jar包放入该目录,然后在eclipse中选择这些jar包后,点击右键菜单 "Build Path" -> "Add to Build Path"即可。
Exception in thread "main" java.lang.ExceptionInInitializerError
at MTest.main(MTest.java:14)
Caused by: com.sun.org.apache.commons.logging.LogConfigurationException: com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException) (Caused by com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException))
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:543)
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:235)
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:209)
at com.sun.org.apache.commons.logging.LogFactory.getLog(LogFactory.java:351)
at com.sun.org.apache.commons.beanutils.BeanUtils.<clinit>(BeanUtils.java:111)
... 1 more
Caused by: com.sun.org.apache.commons.logging.LogConfigurationException: java.lang.NullPointerException (Caused by java.lang.NullPointerException)
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getLogConstructor(LogFactoryImpl.java:397)
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:529)
... 5 more
Caused by: java.lang.NullPointerException
at com.sun.org.apache.commons.logging.impl.LogFactoryImpl.getLogConstructor(LogFactoryImpl.java:374)
... 6 more
我看你的报错信息,好像是用的com.sun.org.apache.commons.logging.LogConfigurationException
你没有将common-beanutils.jar加入你的类路径,因此你的代码会导入 com.sun.org.apache.commons.beanutils.BeanUtils。它本来应该导入的是 org.apache.commons.beanutils.BeanUtils。你只要加入 common-beanutils.jar 就可以了
这个错误然后又报了空指针,我把import改成了java.lang.*错误变了
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
InvocationTargetException cannot be resolved to a type
e cannot be resolved at MTest.main(MTest.java:32)
我import是这样的
import java.lang.*;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;import com.sun.org.apache.commons.beanutils.BeanUtils;
彻底无语了
你要引用org.apache.commons.beanutils.BeanUtils;
而不是com.sun.org.apache.commons.beanutils.BeanUtils;