Raspberry PI 3 B+ Mango and java oracle installation

[JF89]

Hello,

I followed your tutorial to install mango on raspberry PI.

I’m blocked whith the command prompt :

sudo update-alternatives --install java /usr/bin/java /usr/local/java/jdk1.8.0_221/bin/java

as you can see with the following screenshot :

i don’t know linux , and I found on the web a syntax to declare the path for
:/usr/local/java/jdk1.8.0_221/bin but i don’t know if it’s the good syntax.
Here it’s what I wrote on the /etc/environment file :

Is-it correct for the path ?

If yes , have you got any idea of my problem ?

I can obtain JDK as you can see in the following screenshot, but not the java version :

Best regards

[phildunlap]

Hi JF89,

What precisely is your question? How to run that update alternatives command?

Setting JAVA_HOME in the /etc/environment should be sufficient to have Mango find the java executable, and is in fact preferred in the startup scripts to resolving java from the PATH.

I would strongly advise against assigning to the PATH variable in /etc/environment as you seem to be doing.

Have you tried to start Mango?

[JF89]

Hello Phil,

i have many difficulties how to use linux, and i followed your tutorial step by step.
But I encountered the problem with the path.
In your tutorial you said :

Add the following to the file
JAVA_HOME=/usr/local/java/jdk1.8.0_131
If you have path settings add at the end of PATH following :/usr/local/java/jdk1.8.0_131/bin”
save /etc/environment (ctrl+x)

But the syntax is not given by the tutorial.

So that’s why I’m lookink for help.

With your previous comment I know now that the path is not good . But i still don’t know how to write that path in etc/environment.

I tried to start mango with sudo ./ma.sh start command in the bin directory of mango , but mango doesn’t work

is_it because java JRE is not answering ?
because when I check java -version , I have no answer.

When you install JDK, does it install in the same time JRE ?

best regards

[JF89]

here is the screnshot of the check starting mango

[phildunlap]

You can see in Mango/bin/ma-init.sh that it would preferentially use JAVA_HOME.

From your error image, although i do not speak the language, I wonder if you have a /usr/bin/java and if it is executable. But, you should be able to launch Mango using only JAVA_HOME. I would add an echo into ma-init.sh to see what JAVA_HOME is when it is deciding how to find Java.

[JF89]

Hello Phil ,

The file /usr/bin/java is present , but when i try to execute it nothings happens.

ma-init.sh is containing already echo but i don’t know how to add one.
As I said I don’t know how to use linux, just very few commands.

The situation has been improved but not at all.

I can start Mango , but it’s blocked with 5% starting

I was unable to have the good echo when usin oracle jre 1.8.0_221

So with the command sudo update-alternatives --config java , I choose an another version than oracle 1.8.0_221 :

Java-8-openjdk-armhf


Now I can have a good echo for java -version

I updated the etc/environment file with the following
JAVA_HOME= »/usr/lib/jvm/java-8-openjdk-armhf/jre/bin/java»

Of course there’s a problem to launch the display , because I use VNC viewer but I can see the Mango software starting when typing localhost :8080 in the webbrowser bar.

But why Mango is blocked at 5% when starting ?

Is-it because it’s not a oracle version of java ?

Thanks for your help

Best regards

[JF89]

Here is the screenshot of java versions available

[phildunlap]

The screenshot of launch output's stacktrace could be prevented by setting the env.properties entry web.openBrowserOnStartup=false

Those screenshots prove Mango has found Java and that is not the problem, as Mango is using the JAVA_HOME variable to locate Java.

[JF89]

Hello Phil,

It works now , connecting directly to the raspberry PI .

But the display between custom pages or settings pages takes about 3 to 5 seconds delay, and sometimes more.

Is-it due to the ram (only 1 gb with raspian ?)

With a computer core I5 8th generation 3,5 Ghz , 8 GB ram , W10 , the display between pages is less than a second.

Is it as fast for the MangoHTS ( 8GB RAM max ). (display between pages less than a second ?)
Best regards

[phildunlap]

The amount of memory, other things you're doing with your browser, all could affect it. I don't know specifically where the bottlenecks are in your circumstance, nor have I collected that benchmark.