Java Error

[VisualPK]

I'm trying to load a Web Client, but it says this error:


Java Plug-in 1.6.0_31
Using JRE version 1.6.0_31-b05 Java HotSpot(TM) Client VM
User home directory = C:\Users\Jerry and Christine
----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
o: trigger logging
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------


java.lang.UnsupportedClassVersionError: client : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknow n Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.defineClassH elper(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.access$100(U nknown Source)
at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknow n Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.plugin2.applet.Plugin2ClassLoader.findClassHel per(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader.findClass(Un known Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(U nknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Un known Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Un known Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unk nown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unk nown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionR unnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception: java.lang.UnsupportedClassVersionError: client : Unsupported major.minor version 51.0

[Fubarable]

Can you show the relevant code that you wrote for your program?

[VisualPK]

What it's supposed to do is download the cache, but the cache gets stuck at 0%, but here's the code.

[7:11:14 PM] Austin:

 import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.BufferedOutputStream;
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.URLConnection;
import java.net.URL;
import java.util.zip.ZipFile;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.Enumeration;

import sign.signlink;

public class CacheDownloader {

 private client client;

 private final int BUFFER = 1024;

 private final int VERSION = 11; // Version of cache
 private String cacheLink = "http://dl.dropbox.com/u/51164319/cache.zip"; // Link to cache

 private String fileToExtract = getCacheDir() + getArchivedName();

 public CacheDownloader(client client) {
  this.client = client;
 }

 private void drawLoadingText(String text) {
  client.drawLoadingText(35, text);
  //System.out.println(text);
 }


 private void drawLoadingText(int amount, String text) {
  client.drawLoadingText(amount, text);
  //System.out.println(text);
 }

 private String getCacheDir() {
  return signlink.findcachedir();
 }

 private String getCacheLink() {
  return cacheLink;
 }

 private int getCacheVersion() {
  return VERSION;
 }

 public CacheDownloader downloadCache() {
  try {
  File location = new File(getCacheDir());
  File version = new File(getCacheDir() + "/cacheVersion" + getCacheVersion() + ".dat");
  
  if(!location.exists()) {
   //drawLoadingText("Loading new Updates....");
   downloadFile(getCacheLink(), getArchivedName());

   unZip();
   //System.out.println("UNZIP");

   BufferedWriter versionFile = new BufferedWriter(new FileWriter(getCacheDir() + "/cacheVersion" + getCacheVersion() + ".dat"));
   versionFile.close();
  } else {
   if(!version.exists()) {
    //drawLoadingText("Downloading Cache Please wait...");
    downloadFile(getCacheLink(), getArchivedName());

    unZip();
    //System.out.println("UNZIP");

    BufferedWriter versionFile = new BufferedWriter(new FileWriter(getCacheDir() + "/cacheVersion" + getCacheVersion() + ".dat"));
    versionFile.close();

   } else {
    return null;
   }
  }
  } catch(Exception e) {

  }
  return null;
 }
 
 private void downloadFile(String adress, String localFileName) {
  OutputStream out = null;
  URLConnection conn;
  InputStream in = null;
  
  try {

   URL url = new URL(adress);
   out = new BufferedOutputStream(
    new FileOutputStream(getCacheDir() + "/" +localFileName)); 

   conn = url.openConnection();
   in = conn.getInputStream(); 
  
   byte[] data = new byte[BUFFER]; 
 
   int numRead;
   long numWritten = 0;
   int length = conn.getContentLength();

 
   while((numRead = in.read(data)) != -1) {
    out.write(data, 0, numRead);
    numWritten += numRead;

               int percentage = (int)(((double)numWritten / (double)length) * 100D);
    drawLoadingText(percentage, "Downloading Cache " + percentage + "%");

   }

   System.out.println(localFileName + "\t" + numWritten);
   drawLoadingText("Finished downloading "+getArchivedName()+"!");

  } catch (Exception exception) {
   exception.printStackTrace();
  } finally {
   try {
    if (in != null) {
     in.close();
    }
    if (out != null) {
     out.close();
    }
   } catch (IOException ioe) {
   }
  }

 }

 private String getArchivedName() {
  int lastSlashIndex = getCacheLink().lastIndexOf('/');
  if (lastSlashIndex >= 0 
   && lastSlashIndex < getCacheLink().length() -1) { 
   return getCacheLink().substring(lastSlashIndex + 1);
  } else {
   //System.err.println("error retreiving archivaed name.");
  }
  return "";
 }




 private void unZip() {

  try {
       InputStream in = 
    new BufferedInputStream(new FileInputStream(fileToExtract));
   ZipInputStream zin = new ZipInputStream(in);
   ZipEntry e;

   while((e=zin.getNextEntry()) != null) {

                  if(e.isDirectory()) {
     (new File(getCacheDir() + e.getName())).mkdir();
                  } else {

    if (e.getName().equals(fileToExtract)) {
     unzip(zin, fileToExtract);
     break;
    }
            unzip(zin, getCacheDir() + e.getName());
    }
    //System.out.println("unzipping2 " + e.getName());
   }
   zin.close();

  } catch(Exception e) {
   e.printStackTrace();
  }
 }

 private void unzip(ZipInputStream zin, String s) 
  throws IOException {

  FileOutputStream out = new FileOutputStream(s);
  //System.out.println("unzipping " + s);
  byte [] b = new byte[BUFFER];
  int len = 0;

  while ((len = zin.read(b)) != -1) {
   out.write(b,0,len);
  }
  out.close();
 }
}

[Norm]

java.lang.UnsupportedClassVersionError: client : Unsupported major.minor version 51.0

You compiled you code with java version 1.7 and tried to execute it with 1.6.
Update the plugin to 1.7 or recompile to 1.6 version (javac has options to set version)

[VisualPK]

You compiled you code with java version 1.7 and tried to execute it with 1.6.
Update the plugin to 1.7 or recompile to 1.6 version (javac has options to set version)

If we compile it with 1.6, will people with 1.7 be able to use the client?

[Norm]

Yes. Most newer JREs can execute older version classes

[VisualPK]

Yes. Most newer JREs can execute older version classes

We complied with JDK, not JRE. If that's relevant, just thought you should know. Does it make a different?

[Fubarable]

We complied with JDK, not JRE. If that's relevant, just thought you should know. Does it make a different?

You can only compile with the JDK, not the JRE.

[VisualPK]

You can only compile with the JDK, not the JRE.

I'm just talking for the coder now, so our best option to recompile with 1.6?

[Norm]

The javac command has options to produce 1.6 output.