Unsupported major.minor version 50.0

以下摘自Oracle

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Symptoms

error    java.lang.UnsupportedClassVersionError:  ...Unsupported major.minorversion 50.0

Cause

The exception "Unsupported major.minor version .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 | grep version 

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

Check the major version collected in below table

Major version	Java
46	Java 1.2
47	Java 1.3
48	Java 1.4
49	Java 5
50	Java 6
51	Java 7

 

 

 

 

 

 

 

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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