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ionic cordova run android and java version

so I'm basically trying to run my ionic app on an android device, and the command "ionic cordova run android --device" get as far as telling me an error occurred due to:
Requirements check failed for JDK 1.8.x! Detected version: 16.0.0
Check your ANDROID_SDK_ROOT / JAVA_HOME / PATH environment variables.
So, after verifying which java versions I had and successfully changing the version to a 1.8.X, so when I run java -version, it returns:
java version "1.8.0_251"
However, running "ionic cordova run android --device" again, it returns the same original error:
Requirements check failed for JDK 1.8.x! Detected version: 16.0.0
Check your ANDROID_SDK_ROOT / JAVA_HOME / PATH environment variables.
After some more research, I realized that the javac version of it, tells me another version, and it needs to be same I believe. So when I run "javac -version", I get:
javac 16
So... I couldn't figure out how to change the javac version to be the same as java, the only thing I figure is that it could be something with PATH, but the topics get a bit confusing as I'm not sure what to do next?
I have in my .zshrc file the following:
export JAVA_HOME=`/usr/libexec/java_home -v 1.8`
Which I added to fix the original java version issue, but that didn't seem to have changed the javac as well.
So after running the commands "which java" and "which javac" respectively, I get:
/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
/usr/bin/javac
I assume there's something funny in here, huh? But this is basically where I'm stuck. I'm not even sure if this is the issue, but it's one of those things I think I'm just doing something stupid without realising it lol
Any help is greatly appreciated!

Goal
You are describing that you want "java" and "javac" to both resolve to JDK 1.8. From there, you'll be able to use ionic cordova to do things.
Starting point
Here are various commands you've run, along with their output (I changed format to make it look like actual commands being run, and the output):
Java compiler ("javac") is for JDK 16, and lives at /usr/bin/javac (which might be an alias to another location).
% javac -version
javac 16
% which javac
/usr/bin/javac
Java runtime – the thing which starts the Java Virtual Machine – is resolving somewhere else
altogether – /Library/Internet Plug-Ins/... – and shows up as version 1.8, not 16:
% which java
/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
% java -version
java version "1.8.0_251"
A few takeaways..
You have JDK 16 installed, resolving to /usr/bin
You have something separately installed at "/Library/Internet.." – this is most likely a JRE (not a JDK), and is version 1.8
Fix
Install JDK 1.8 – this will give you a compiler and runtime that are both version 1.8
Follow download steps here: https://www.oracle.com/java/technologies/downloads/#java8 Once installed, you should be able to switch to using JDK 1.8, and confirm versions of both the compiler (javac) and the runtime (java) binaries.
There are various ways to set JAVA_HOME and manage multiple JDK installs – this is the simplest way to just get past the issue you're facing: set JAVA_HOME manually. This will be system dependent, but below is an example from my local system.
% export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_341.jdk/Contents/Home
Verify that "java" resolves to your new 1.8 install:
% java -version
java version "1.8.0_341"
Java(TM) SE Runtime Environment (build 1.8.0_341-b10)
Java HotSpot(TM) 64-Bit Server VM (build 25.341-b10, mixed mode)
Verify that "javac" also resolves to your new 1.8 install:
% javac -version
javac 1.8.0_341
If you see anything other than above, something else is going on, and we would need to see more details, including whatever output happened from following the above steps.

How many java versions do i have installed on my Mac?

I'm a bit confused now. When I run the command java --version in the terminal i get: java 13.0.1. When I open the system preferences and click the java app and then about, i see it says Java version 8 1.8.0_231
Does that mean I have 8, 13 or both?
When I check through the java app.
When I check through the terminal.
When i check for all JDK installed on my system (only 1 version pop ups).

You can have multiple JDK installed in one machine but you can have only one version set as default Java SDK. Looks like you have Java 13 set as default.
Try running the following :
echo $JAVA_HOME
You can also go to the tab Java and see the list of all Java Runtime Environments (JRE.)
Please note that just because you have multiple JREs available doesnot mean all corresponding SDK are also there.

You can have many version of java on your Mac. But you can run only one of this in a process.
On my Mac, system preferences run with java path :
/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
But in terminal, this run with java path:
/usr/bin/java
I think you can replace java file in /usr/bin by another version java you want.

that means you jdk version is 13 , and your jre version is 1.8.
jre is used for running java apps ,and the jdk(java development kit) is for building apps with java language. java jdk is like the android sdk

Run Glassfish on Java 7 with Java 8 installed on Windows box

I am working on a legacy project with Glassfish 3 and Java 7. The problem is in order to run Eclipse, I need Java 8. When I install Java 8, I can no longer run Glassfish under Java 7 for some reason.
I do see the two JDKs in control panel for User tab in Java Runtime Environment Settings, but under System once I install Java 8, I only see Java 8 there. So it just runs under Java 8 from what I can tell.
This is my first week of Java.

Simply specify the needed JDK for your Glassfish domain:
Find this configuration file: C:\servers\glassfish\config\asenv.bat (this path is an example)
Edit the file, comment the previous JDK and add the wanted one:
REM set AS_JAVA=C:\Program Files\Java\jdk1.8\..
set AS_JAVA=C:\Program Files\Java\jdk1.7\..

When you install a new JVM, usually it sets itself as the default version on that platform which is the first one found on the Path environment variable. In order to find what version is the default one, run this command: java -version and the output will be something like:
openjdk version "1.8.0_111"
OpenJDK Runtime Environment (build 1.8.0_111-8u111-b14-2ubuntu0.16.10.2-b14)
OpenJDK 64-Bit Server VM (build 25.111-b14, mixed mode)
As you see in this case the default one is OpenJDK-8.
If you want to change that, you have to do some changes which depend on the platform can vary but usually you should:
Change JAVA_HOME environment variable to point to desired JVM
installation path
Add desired JVM <installation-path>/bin to Path environment variable and remove other JVM paths.
(Detailed example for Windows, Example for Ubuntu)
Notice that, this potentially could affect every program that uses Java and does not explicitly reference a specific version of Java in its config.
But If you want the default version to remain intact and only make an exception for some programs you have to do it in their config/settings.
For Example for Eclipse you can modify eclipse.ini file and specify the JVM it uses by adding this line (more info):
-vm
/opt/oracle-jdk-1.8.0/bin/java
or for Windows:
-vm
C:\Java\JDK\1.8\bin\javaw.exe
there is a similar config for glassfish too. You can choose which JVM should be the default version and which the one exceptional programs gonna use, In your case I recommend that keep version 7 as default and change eclipse config to use version 8.

Setting Java home enviroment variable in OSX Mavericks

I am having issues with my Java path.
I have installed the latest version of Java 1.7.0_51. When I open the Java control panel it tells me "Your system has the recommended version of Java."
However when I go to terminal and type java -version I get
java version "1.6.0_32"
So after searching around I came across this SO Question which tells me that my Java home environment variable needs to be set.
I then opened the bash_profile file and added the below line to the top of the file, above my Python path info.
export JAVA_HOME=`/usr/libexec/java_home -v 1.7.0_51`
# Setting PATH for Python 2.7
# The orginal version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/2.7/bin:${PATH}"
export PATH
NOTE: I have tried this with both -v 1.7.0_51 and -v 1.7
I save the file and recheck in terminal but it is still showing
java version "1.6.0_32"
when I restart Terminal I do however see
Last login: Wed Feb 19 23:32:19 on ttys000
Unable to find any JVMs matching version "1.7".
localhost:/ user$
Note: Unable to find any JVMs matching version "1.7".
So it is trying to look for my 1.7, but just not finding it.
What am I doing wrong?

Check whether there is an old version existed in the path
echo $PATH
Then set the java 1.7 bin directory.
export PATH=/usr/libexec/java_1.7_home/bin:$PATH
Then try to type in "java -version" in terminal to check the version

Ok, I think this must be specific to me. As above the Java control panel was saying that java 7 was installed. Also when i tried
/Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java -version
I would get
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
But no mater what way I installed the JDK it would not work. It just didn't seem to appear anywhere on my machine. I still don't know why, but uninstalling (by simply deleting the 1.6 folder) the existing Java 6 from my machine and once again installing Java 7 JDK eventually fixed it.
Please give the up-votes to #diaz994 above.

How to install JPype on OS X Lion to use with Neo4j?

I am trying to use Neo4j for a project, and want to interface with it through Python since I'm a newbie to programming and don't know any Java. I'm following the installation instructions, but I'm stuck on
the first step, which is to install JPype.
I'm using OS X 10.7 (lion). I think my configuration is pretty standard
with Python 2.7.2 downloaded from the Python website and Java 1.6.0 downloaded from the Apple website.
When I run
% sudo python setup.py install
On the JPype installer, I get about a 100 lines of error code about various .h files, then it
terminates with the lines:
lipo: can't figure out the architecture type of: /var/tmp//
ccwOzLi9.out
error: command 'gcc-4.2' failed with exit status 1
I found a blog post about a gcc error with JPype, but I followed the instructions there to no avail. I also emailed the author of that post, and he told me had never actually used JPype, had been working in OS X 10.6, and didn't have any insight.
I also emailed the creator of JPype, who told me that he only uses Windows, and has no idea how to make the install work on OS X. But if we can solve this, I can point him to the answer and maybe he can add the solution to the JPype documentation and help lots of other people as well!
So, anyone know what I'm doing wrong? I would like to use Neo4j, but I
don't know Java so I'm at a complete loss for how to fix a compiler
error.
Based on reading every Google result available, my two running
theories are that:
I'm somehow using a 32-bit version of Python or of Java (though I
used standard official installations and can't figure out how to
switch to 64-bit or if that's even possible)
The JPype files can only be compiled using GCC 4.0 instead of 4.2.
But I can't find anything online about how to rollback to GCC 4.0 (or
if it comes shipped with 2011 MacBooks and there is some way to force
JPype to compile with that instead).
There is another similar question, but the solution there is to use a different adapter that goes through REST instead of hooking directly into Java. I will try that if I have to, but I would really rather use the recommended Neo4j method if it's possible.

I'm not a Python guy, but tried installing JPype on my machine:
% uname -a
Darwin fatty-i7.local.tld 11.2.0 Darwin Kernel Version 11.2.0: Tue Aug 9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64 x86_64
% java -version
java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11-402-11M3527)
Java HotSpot(TM) 64-Bit Server VM (build 20.4-b02-402, mixed mode)
On OSX Lion, the latest JDK appears to be located here:
/Developer/SDKs/MacOSX10.7.sdk/System/Library/Frameworks/JavaVM.framework/
A little googling turned up this post: http://blog.y3xz.com/post/5037243230/installing-jpype-on-mac-os-x
I followed those instructions to modify setup.py, then ran sudo python setup.py install with no problems.
Does that help?

On my Lion, the "include" directory in the JDK was gone, so JPype couldn't find jni.h.
I updated setup.py in two places, one to set where to find jar libraries:
def setupMacOSX(self):
self.javaHome = '/System/Library/Frameworks/JavaVM.framework'
self.jdkInclude = ""
self.libraries = ["dl"]
self.libraryDir = [self.javaHome+"/Home/lib"]
self.macros = [('MACOSX',1)]
And one to set where to find jni.h:
def setupInclusion(self):
self.includeDirs = [
self.javaHome+"/Headers",
<other stuff>

For me,
self.javaHome = '/System/Library/Frameworks/JavaVM.framework/Versions/Current/'
worked.
$ uname -a Darwin 11.4.0 Darwin Kernel Version 11.4.0: Mon Apr 9 19:32:15 PDT 2012; root:xnu-1699.26.8~1/RELEASE_X86_64 x86_64
$ java -version java version "1.6.0_33" Java(TM) SE Runtime Environment (build 1.6.0_33-b03-424-11M3720) Java HotSpot(TM) 64-Bit Server VM (build 20.8-b03-424, mixed mode)

Here are directions I put in my README to install JPype on OS X 10.7. Same idea as the answers here but different enough to warrant the submission.
The python interface to java (JPype) needs mods to the setup.py:
In summary, you need to make sure the JPype setup.py script can see your Java SDK "Headers" and "Home" directory
I had to install Java from Apple first since my default OS X installation did not come with Headers in the typical Java install path which I found by executing:
/usr/libexec/java_home
If you do happen to have a Headers dir, you probably do not need to reinstall Java and can set the path vars below based on your java HOME directory which is likely different from those in these directions
After I installed Java, I found the new installation in:
/Library/Java/JavaVirtualMachines/
My Home directory was:
/Library/Java/JavaVirtualMachines/1.6.0_37-b06-434.jdk/Contents/Home/
and my Header directory was:
/Library/Java/JavaVirtualMachines/1.6.0_37-b06-434.jdk/Contents/Headers/
1) The JPype script assumes that Headers is within the Home directory but it's not, so I changed the Home path var and created a new Content path var in the setup.py script - In setupMacOSX(self):
self.javaHome = '/Library/Java/JavaVirtualMachines/1.6.0_37-b06-434.jdk/Contents/Home/'
self.javaContents = '/Library/Java/JavaVirtualMachines/1.6.0_37-b06-434.jdk/Contents/'
2) In setupMacOSX(self), change self.libraryDir:
self.libraryDir = [self.javaContents + "/Libraries"]
Note that this step was mentioned as required but I did not have to do this for it to work so maybe try without it first
3) In setupInclusion, add paths to your "Home/include" dir and your "Headers" dir:
self.javaHome+"/include",
self.javaContents + "/Headers",
4) Running the installation should now work:
sudo python setup.py install

For everyone who is still trying to install Jpype but has meanwhile updated Mac OS: Andreas Kolleger's answer just works fine, but with XCode 4.3 the path changed to /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk/System/Library/Frameworks/JavaVM.framework/Versions/Current/
In ML it's MacOSX10.8.sdk. At least on my system. :)

For me, on Mountain Lion
self.javaHome = '/System/Library/Frameworks/JavaVM.framework/'
worked.
$uname -a
Darwin 12.0.0 Darwin Kernel Version 12.0.0: Sun Jun 24 23:00:16 PDT 2012; root:xnu-2050.7.9~1/RELEASE_X86_64 x86_64
$ java -version
java version "1.6.0_33"
Java(TM) SE Runtime Environment (build 1.6.0_33-b03-424-11M3720)
Java HotSpot(TM) 64-Bit Server VM (build 20.8-b03-424, mixed mode)

I did the same, but choosing
self.javaHome = '/Developer/SDKs/**MacOSX10.6.sdk**/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/'
instead
self.javaHome = '/Developer/SDKs/**MacOSX10.7.sdk**/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/'
realize that I use version 6 vs 7. With the 7 version I got the same errors that the beginning.

To make Will's answer a bit more specific: I had to modify the setupInclusion(self) method by adding the directory path he suggested, ie, '/System/Library/Frameworks/JavaVM.framework/Headers' on Mountain Lion (java version 1.6). With that the installation of JPype succeeded (though gave a bunch of warnings...)

Here's what worked for me - recommend you put the first line in your profile.
export JAVA_HOME=$(/usr/libexec/java_home)
cd $JAVA_HOME
sudo ln -s include Headers
sudo cp include/darwin/* include/
cd -
Note that instead of changing setup.py, I'm changing my JDK install. This has the advantage of fixing the issue for other projects.

For those trying to install on Mountain Lion, I had to further edit the setup.py file to include the header files here:
/System/Library/Frameworks/JavaVM.framework/Versions/Current/Headers