hadoop installation errors in ubuntu 19.10

I was installing Hadoop on Ubuntu 19.10 I got following errors I am comipiling https://hadoop.apache.org/releases.html file version https://www.apache.org/dyn/closer.cgi/hadoop/common/hadoop-3.1.3/hadoop-3.1.3-src.tar.gz from instructions given in BUILDING.txt file during compilation I get following error

In file included from ./google/protobuf/io/tokenizer.h:42:0,
                 from google/protobuf/io/tokenizer.cc:91:
./google/protobuf/stubs/strutil.h: In function 'google::protobuf::int64 google::protobuf::strto64(const char*, char**, int)':
./google/protobuf/stubs/strutil.h:319:25: warning: typedef 'sizeof_int64_is_not_sizeof_long_long' locally defined but not used [-Wunused-local-typedefs]
                         sizeof_int64_is_not_sizeof_long_long);
                         ^
./google/protobuf/stubs/common.h:382:11: note: in definition of macro 'GOOGLE_COMPILE_ASSERT'
           msg[bool(expr) ? 1 : -1]
           ^
./google/protobuf/stubs/strutil.h: In function 'google::protobuf::uint64 google::protobuf::strtou64(const char*, char**, int)':
./google/protobuf/stubs/strutil.h:325:25: warning: typedef 'sizeof_uint64_is_not_sizeof_long_long' locally defined but not used [-Wunused-local-typedefs]
                         sizeof_uint64_is_not_sizeof_long_long);
                         ^
./google/protobuf/stubs/common.h:382:11: note: in definition of macro 'GOOGLE_COMPILE_ASSERT'
 msg[bool(expr) ? 1 : -1]
           ^

How to solve above errors?

debian@osboxes:~/hadoop/hadoop-3.1.3-src$ sudo apt-get update --fix-missing
Hit:1 http://ppa.launchpad.net/linuxuprising/java/ubuntu eoan InRelease        
Hit:2 http://archive.ubuntu.com/ubuntu eoan InRelease                          
Get:3 http://archive.ubuntu.com/ubuntu eoan-updates InRelease [97.5 kB]        
Ign:4 https://download.docker.com/linux/ubuntu eoan InRelease
Err:5 https://download.docker.com/linux/ubuntu eoan Release                    
  404  Not Found [IP: 13.249.210.98 443]
Get:6 http://archive.ubuntu.com/ubuntu eoan-security InRelease [97.5 kB]       
Get:7 http://archive.ubuntu.com/ubuntu eoan-backports InRelease [88.8 kB]      
Reading package lists... Done                                                  
E: The repository 'https://download.docker.com/linux/ubuntu eoan Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

and also

debian@osboxes:~/hadoop/hadoop-3.1.3-src$ sudo apt-get update
Err:1 http://ppa.launchpad.net/linuxuprising/java/ubuntu eoan InRelease
  Temporary failure resolving 'ppa.launchpad.net'
Err:2 https://download.docker.com/linux/ubuntu eoan InRelease            
  Temporary failure resolving 'download.docker.com'
Err:3 http://archive.ubuntu.com/ubuntu eoan InRelease                    
  Temporary failure resolving 'archive.ubuntu.com'
Err:4 http://archive.ubuntu.com/ubuntu eoan-updates InRelease
  Temporary failure resolving 'archive.ubuntu.com'
Err:5 http://archive.ubuntu.com/ubuntu eoan-security InRelease
  Temporary failure resolving 'archive.ubuntu.com'
Err:6 http://archive.ubuntu.com/ubuntu eoan-backports InRelease
  Temporary failure resolving 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan-updates/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan-security/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan-backports/InRelease  Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch https://download.docker.com/linux/ubuntu/dists/eoan/InRelease  Temporary failure resolving 'download.docker.com'
W: Failed to fetch http://ppa.launchpad.net/linuxuprising/java/ubuntu/dists/eoan/InRelease  Temporary failure resolving 'ppa.launchpad.net'
W: Some index files failed to download. They have been ignored, or old ones used instead.
debian@osboxes:~/Hadoop

edit
after a struggle of 2-3 days installing and re installing proceeding with re building I think I have succeeded. I have got some thing which I can see in screenshot as below

Now what should I do next from here? This seems to be some kind of environment of Hadoop but I am new to this so I do not know what to do next? I have to do some assignment questions for programming like I want to learn also Hadoop from the shell I see above what command should I type or how to do programming etc in it.