Unable to run Java GUI programs with Ubuntu

Question

I am learning GUI in Java  and for that I have created a demo program   import java awt     public class FrameDemo extends Frame        public FrameDemo            super  Frame Demo            setSize 200  200           setVisible true              public static void main String args             new FrameDemo                  It was compiled successfully  But when I tried to execute the program  I found the following error   Exception in thread  main  java awt HeadlessException     at java awt GraphicsEnvironment checkHeadless GraphicsEnvironment java 173      at java awt Window  lt init gt  Window java 437      at java awt Frame  lt init gt  Frame java 419      at FrameDemo  lt init gt  FrameDemo java 4      at FrameDemo main FrameDemo java 9    I am using Xubuntu 10 10 and java -version gives   java version  1 6 0 20  OpenJDK Runtime Environment  IcedTea6 1 9 5   6b20-1 9 5-0ubuntu1  OpenJDK Client VM  build 19 0-b09  mixed mode  sharing    What should I to do   One more thing  It is the same sort of error I got when I tried to execute Dr  Java and HJSplit s jar file

User · Answer

I too had OpenJDK on my Ubuntu machine     java -version java version  1 7 0 51  OpenJDK Runtime Environment  IcedTea 2 4 4   7u51-2 4 4-0ubuntu0 13 04 2  OpenJDK 64-Bit Server VM  build 24 45-b08  mixed mode    Replacing OpenJDK with the HotSpot VM works fine   sudo apt-get autoremove openjdk-7-jre-headless   How to install the JDK on Ubuntu  Linux

User · Answer

Check your X Window environment variables using the  env  command

User · Answer

This command worked for me   Sudo dnf install java-1 8 0-openjdk  Fedora   Sudo apt-get install java-1 8 0-openjdk   Should work for Ubuntu

User · Answer

In my case  -Djava awt headless true   was set  indirectly by a Maven configuration   I had to actively use  -Djava awt headless false   to override this

User · Answer

I stopped getting this exception when I installed default-jdk using apt  I m running Ubuntu 14 04  Trusty Tahr   and the problem appears to have been the result of having a  headless  Java installed  All I did was   sudo apt-get install default-jdk

User · Answer

Ubuntu has the option to install a headless Java -- this means without graphics libraries   This wasn t always the case  but I encountered this while trying to run a Java text editor on 10 10 the other day   Run the following command to install a JDK that has these libraries  sudo apt-get install openjdk-6-jdk  EDIT  Actually  looking at my config  you might need the JRE   If that s the case  run  sudo apt-get install openjdk-6-jre

User · Answer

Check what your environment variable DISPLAY s value is  Try running a simple X application from the command line  If it works  check DISPLAY s value for the right value   You can experiment with different values of and environment variable on a per invocation basis by doing the following on the command line    DISPLAY  0 0  lt your-java-executable-here gt    How are you calling your program

User · Answer

I would check with another Java implementation vendor  Preferrably Oracle Sun Java  http   www java com en    The open-source implementations unfortunately differ in weird ways

User · Answer

Use JFrame instead of Frame  And do not extend from JFrame  Just write a class that has a JFrame property named gui  which configures this JFrame with the available methods  because it is better style doing it like this  Extending here is wrong the use of OOP

[java] Unable to run Java GUI programs with Ubuntu

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