相关疑难解决方法(0)

我按照以下步骤安装了maven :(教程)

JAVA_HOME=/Library/Java/Home
export M2_HOME=/Users/steven/zimmermann/maven
export M2=$M2_HOME/bin
export PATH=$M2:$PATH

echo $JAVA_HOME
echo $M2_HOME
echo $M2
echo $PATH

nano .bash_profile

然后我在.bash_profile中写了回声,就像这样:

JAVA_HOME=/usr/libexec/java_home
M2_HOME=/path/to/your/apache-maven-3.x.x
M2=/path/to/your/apache-maven-3.x.x/bin
PATH=/path/to/maven/bin:/$….bla-bla-bla…

我也在.bashrc中写了这个

export M2_HOME=/Users/steven/zimmermann/maven
export M2=$M2_HOME/bin
export PATH=$M2:$PATH

现在,当我想检查版本(mvn -v)时,我得到以下异常:我认为有一些版本错误,但我不知道.

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/maven/cli/MavenCli : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:401)
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:254)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
    at org.codehaus.plexus.classworlds.launcher.Launcher.getMainClass(Launcher.java:144)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:266) …

可能重复:
不支持的主要.minor版本51.0

我安装了JDK7,一个简单的hello word程序得到编译,但是当我运行它时,我得到了以下异常.

Exception in thread "main" java.lang.UnsupportedClassVersionError: a (Unsupported major.minor version 51.0)
    at java.lang.ClassLoader.defineClass0(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$100(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)

我检查java -version了命令提示符,它显示了Java版本1.4.2_03但是当我尝试从java.com安装新的java版本时它说我推荐了Java 7版本.

我有:

<build>
  <pluginManagement>
     <plugins>
        <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>3.1</version>
           <configuration>
              <source>1.6</source>
              <target>1.6</target>
           </configuration>
        </plugin>
     </plugins>
  </pluginManagement>
</build>

然而我宣布:

public enum DirectoryWatchService {

    INSTANCE;

    private java.util.Optional<String> test;
    private java.nio.file.Files files;
}

Eclipse没有打扰.IntelliJ也不是.即使是Maven也不会打扰.我甚至可以做一个mvn清洁包.在没有任何警告的情况下构建糟糕的东西.