Unsupported major.minor version 50.0

标签：compiler   java   eclipse   jdk   class   

以下摘自Oracle

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Symptoms

Cause

The exception "Unsupported major.minor version <yy>.0" is raised when the run-time Java release is a lower than the Java release used to compile the class.

For example a class compiled using Java 6 (major.minor = 50.0) can not be run with Java 5 (major.minor = 49.0) or Java 1.4.2 (major.minor = 48.0) and thus raises

Unsupported major.minor version 50.0

Note that no exception is raised when class is compiled with Java 5 (major.minor = 49.0) and then run with Java 6 (major.minor = 50.0). It‘s fine to run the class with a newer Java version than it was compiled with.

Solution

To resolve the error the class needs to be compiled using the same or lower Java release as used on run-time. There are 2 options to accomplish this

1. Compile the class with the same (or older) Java version as used on run-time
2. Compile the class and use the parameters -source and -target to mimic class is compiled with lower version. 

For example when having Java 6 running compilation as 

# javac -source 1.5 -target 1.5 myclass.java

makes that the both source (.java) and target (.class) are interpreted as Java 5 and class will reference major.minor = 49.0 (see below table)

 Hints and tips:

• Ensure that the javac and java executable are used from the same JDK_HOME.

Run # which javac and # which java to confirm.

The environment setting PATH may resolve java from $IAS_ORACLE_HOME/appsutil/jdk/jre/bin, while thejavac is located in $IAS_ORACLE_HOME/appsutil/jdk/bin. This causes that the javac is taken from another JDK_HOME which may have a different (and possible newer) Java version.  To prevent this add the $IAS_ORACLE_HOME/appsutil/jdk/bin at the start of the PATH settin, so javac is used from the correct JDK_HOME

• To verify the version class is compiled use the javap utility coming with the JDK ( it‘s not included with the JRE only installation)

Run # javap -verbose <class> | grep version 

note: provide the name without extenstion, so use myclass instead of myclass.class

Check the major version collected in below table

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通过.class文件确认major,minor版本的方法

1.在eclipse中打开class文件，可查到

2.通过javap命令查看，例如javap classname -verbose > C:\major_version.txt

因此，编译及运行的java版本相同，例如，46是1.4默认编译的major版本，需要使用1.4 compiler进行编译

Unsupported major.minor version 50.0,布布扣,bubuko.com

Unsupported major.minor version 50.0

标签：compiler   java   eclipse   jdk   class   

原文地址：http://blog.csdn.net/battlehawk/article/details/38533563