问题

This question already has an answer here:

How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version 48 answers

Pictures:

$\"Command$ Command Prompt showing versions

$\"Picture$ Picture of error

Hello.java

import java.applet.Applet;
import java.awt.*;

public class Hello extends Applet {

    // Java applet to draw \"Hello World\"
    public void paint (Graphics page) {
        page.drawString (\"Hello World!\", 50, 50);
    }
}

Hello.html

<HTML>
    <HEAD>
        <TITLE>HelloWorld Applet</TITLE>
    </HEAD>

    <BODY>
        <APPLET CODE=\"Hello.class\" WIDTH=300 HEIGHT=150>
        </APPLET>
    </BODY>
</HTML>

Error

Hello : Unsupported major.minor version 52.0

What may the problem be?

回答1:

The issue is because of Java version mismatch. Referring to the Wikipedia Java Class Reference:

Java SE 12 = 56 (0x38 hex)
Java SE 11 = 55 (0x37 hex)
Java SE 10 = 54
Java SE 9 = 53
Java SE 8 = 52
Java SE 7 = 51
Java SE 6.0 = 50
Java SE 5.0 = 49
JDK 1.4 = 48
JDK 1.3 = 47
JDK 1.2 = 46
JDK 1.1 = 45

These are the assigned major numbers. The error regarding the unsupported major.minor version is because during compile time you are using a higher JDK and a lower JDK during runtime.

Thus, the 'major.minor version 52.0' error is possibly because the jar was compiled in JDK 1.8, but you are trying to run it using a JDK 1.7 environment. The reported number is the required number, not the number you are using. To solve this, it's always better to have the JDK and JRE pointed to the same version.

In IntelliJ IDEA,

Go to Maven Settings → Maven → Importing. Set the JDK for importer to 1.8.
Go to Maven Settings → Maven → Runner. Set the JRE to 1.8.
Go to menu File* → Project Structure → SDKs. Make sure the JDK home path is set to 1.8.

Restart IntelliJ IDEA.

Another approach which might help is by instructing IntelliJ IDEA which JDK version to start up with.

Go to: /Applications/IntelliJ\ IDEA\ 15\ CE.app/Contents/Info.plist and replace the JVM version with:

<key>JVMVersion</key>
<string>1.8*</string>

回答2:

The smart way to fix that problem is to compile using the latest SDK and use the cross compilation options when compiling. To use the options completely correctly requires the rt.jar of a JRE (not JDK) of the target version.

Given the nature of that applet, it looks like it could be compiled for use with Java 1.1.

回答3:

You will need to change your compiler compliance level back to 1.7 in your IDE.

This can be done in the preferences settings of your IDE. For example, in Eclipse go to menu Windows → Preferences, select Java, and expand it. Then select Compiler and change the compliance level to 1.7. I am sure this will work from there.

回答4:

You must run and compile your application with the same version of Java.

If you're using Eclipse you should do 2 things:

In Eclipse, click on "Window > Preferences", and in the window that appears, on the left side, under "Java", click on "Installed JREs", click on "Add..." and navigate to the folder that contains the JDK.
Right-click on your project and click on "Properties", in the window that appears, on the left side, click on "Java Compiler" and uncheck "Use compliance from execution environment on the Java Build Path", this allows you to choose in the the list "Compiler compilance level" the same version that you set in the previous step.

回答5:

You need to upgrade your Java version to Java 8.

Download latest Java archive

Download latest Java SE Development Kit 8 release from its official download page or use following commands to download from the shell.

For 64 bit

 # cd /opt/

 # wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u51-b16/jdk-8u51-linux-x64.tar.gz"

 # tar xzf jdk-8u51-linux-x64.tar.gz

For 32 bit

 # cd /opt/

 # wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u51-b16/jdk-8u51-linux-i586.tar.gz"

  # tar xzf jdk-8u51-linux-i586.tar.gz

Note: If the above wget command doesn’t not work for you, watch this example video to download the Java source archive using the terminal.

Install Java with alternatives

After extracting the archive file, use the alternatives command to install it. The alternatives command is available in the chkconfig package.

 # cd /opt/jdk1.8.0_51/

 # alternatives --install /usr/bin/java java /opt/jdk1.8.0_51/bin/java 2

 # alternatives --config java

At this point Java 8 has been successfully installed on your system. We also recommend to setup javac and jar commands path using alternatives:

 # alternatives --install /usr/bin/jar jar /opt/jdk1.8.0_51/bin/jar 2

 # alternatives --install /usr/bin/javac javac /opt/jdk1.8.0_51/bin/javac 2

 # alternatives --set jar /opt/jdk1.8.0_51/bin/jar

 # alternatives --set javac /opt/jdk1.8.0_51/bin/javac

Check installed Java version

Check the installed version of Java using the following command.

root@tecadmin ~# java -version

java version "1.8.0_51"
Java(TM) SE Runtime Environment (build 1.8.0_51-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.51-b03, mixed mode)

Configuring Environment Variables

Most of Java-based applications use environment variables to work. Set the Java environment variables using the following commands:

Setup JAVA_HOME Variable

# export JAVA_HOME=/opt/jdk1.8.0_51
Setup JRE_HOME Variable

# export JRE_HOME=$JAVA_HOME/jre
Setup PATH Variable

# export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH

Note that the change to the PATH variable put the new Java bin folders first so that they override any existing java/bins in the path. It is a bit sloppy to leave two java/bin folders in your path so you should be advised to clean those up as a separate task.

Also, put all above environment variables in the /etc/environment file for auto loading on system boot.

回答6:

I had the same problem... a JDK and plug-in version conflict.

I compiled using 1.8 ... the latest one, and that message started to appear. So I've searched for the JRE 7 (http://www.oracle.com/technetwork/java/javase/downloads/server-jre7-downloads-1931105.html)... and installed it... again... Now 1.8 and 1.7 in the same computer.

Using NetBeans, and compiling, and targeting to version 1.7, fixed my problem.

回答7:

If you have a problem in Android Studio and you have installed Android N, change the Android rendering version with an older one and the problem will disappear.

回答8:

If you're using the NetBeans IDE, right click on the project and choose Properties and go to sources, and you can change the Source/Binary Format to a lower JDK version.

回答9:

Unsupported major.minor version 52.0 comes when you are trying to run a class compiled using Java 1.8 compiler into a lower JRE version e.g. JRE 1.7 or JRE 1.6. Simplest way to fix this error is install the latest Java release i.e. Java 8 and run your program.

Read more: http://javarevisited.blogspot.com/2015/05/fixing-unsupported-majorminor-version.html#ixzz4AVD4Evgv

回答10:

It happens when you compile your projects on higher version of java(say jdk 1.8) and then run it on a lower version (say jdk 1.7).

If you have JRE-1.7 library in your project path then ,

1.Right click on project

2.Go to Properties

3.Select Project Facets

4.Find Java in rows and then choose version (say 1.7) if using JRE-1.7

5.Click Apply and run your project.

回答11:

I could solve the same problem using the below solution.

In my project, I added a JAR file which were created in Java 8. And my project was referring to JRE 7. When I changed project JRE to 8, my problem was solved.

Steps:

In Eclipse, right click on the project name in project explorer → Build path → Libraries → click on JRE version → click Edit → Installed JRE → Add → Standerd VM → select JRE home click-path (path should be localePath\java\jdk1.8.0_25\jre) → provide name → Save → select same JRE for project → Finish → OK. Refresh/build project once → try to run your Java file. It should work.

回答12:

I solved my problem by removing old versions of JRE and installing JRE 8.

回答13:

I had Java 1.7 & 1.8 installed (with SBT 2.4 that requires Java 1.8). Even though my project was linked to Java 1.8, I had to change the JAVA_HOME environment variable to point 1.8. Finally, problem solved.

回答14:

If you are using Eclipse, make sure your menu Project → Properties → Java build path → libraries → JRE system library matches your project requirements (as shown in the image).

回答15:

All you need to do to solve the problem is... to make sure your version of Java is the same for both compiling and running. No matter what tools or IDEs you are using.

回答16:

If you are using Linux and you have different versions of Java installed, use the following command:

sudo update-alternatives --config java

This will give a quick way of switching between the Java versions installed on the system. By choosing Java 8 I will solve your problem.

回答17:

This occurred to me when I installed a fresh Java 1.8, but left the old command line interpreter open.

It had an old path and kept on executing the application with Java 1.7 whereas project was already built with Java 1.8.

回答18:

If your JDK version is right. Another reason that may cause this error is that your Android Studio is in a low version, but your Gradle version is too high. Upgrade your IDE to a newer version may help this.

回答19:

You need to use JDK 1.7.0 rather than JDK 1.8.0.

To make sure it, you need to delete JDK 1.8.0 on your computer.

If you use Mac, you need to delete:

/Library/Java/JavaVirtualMachines/jdk.jdk

/Library/PreferencePanes/JavaControlPanel.prefPane

/Library/Internet Plug-Ins/JavaAppletPlugin.plugin

Then, you need to reinstall JDK 1.7.0, and you will succeed to generate the .jar file.

回答20:

Upgrade your Andorra version to JDK 1.8.

This is a version mismatch that your compiler is looking for Java version 8 and you have Java version 7.

You can run an app build in version 7 in version 8, but you can't do vice versa because when it comes to higher levels, versions are embedded with more features, enhancements rather than previous versions.

Download JDK version from this link

And set your JDK path for this

回答21:

You may want to check your Run Configurations setting if you're using Eclipse v4.4 (Luna) and have already completed all steps mentioned above.

There could be several possibilities that cause this error. The root cause is a mismatch of the project require compilation in JDK1.8/JRE8 while the environment compiler is JDK1.7/JRE7.

You can check my blog post to go through all your settings are correct.

回答22:

None of these answers helped me, but I found a solution.
I had a webproject used in Wildfly 8.2, built with Maven, source and target was set to 1.8 on maven-compiler-plugin, as well as all Eclipse and Maven settings were set to Java 1.8. The problem was that Wildfly 8.2 cannot handle Java 1.8, so I had to set everything to 1.7 and it worked.

回答23:

Just want to add this. I had this problem today. Adjusted the settings in my project, rebuilt, and same problem. I had (incorrectly) assumed that changing the settings in my project (Eclipse) would cause the projects on which my project depends to be recompiled also. Adjusting the settings to all of the projects up the dependency tree solved the problem.

回答24:

Just go to http://java.com/en/download/ and update your version of JRE

回答25:

If you are using IntelliJ IDEA, go to Project Structure (Ctrl + Alt + Shift + S), and you can change your project's JDK.

回答26:

I ran into this issue in Eclipse on Mac OS X v10.9 (Mavericks). I tried many answers on Stack Overflow ... finally, after a full day I *installed a fresh version of the Android SDK (and updated Eclipse, menu Project → Properties → Android to use the new path)*.

I had to get SDK updates, but only pulling down those updates I thought were necessary, avoiding APIs I were not working with (like Wear and TV) .. and that did the trick. Apparently, it seems I had corrupted my SDK somewhere along the way.

BTW .. I did see the error re-surface with one project in my workspace, but it seemed related to an import of appcompat-7, which I was not using. After rm-ing that project, so far haven't seen the issue resurface.

来源：https://stackoverflow.com/questions/22489398/unsupported-major-minor-version-52-0

标签

java

applet

version

unsupported-class-version

Unsupported major.minor version 52.0 [duplicate]

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