$ sudo apt-get update
$ sudo apt-get install libpostgresql-jdbc-java 

libpostgresql-jdbc-java is installed in your system.

Make ensure the libpostgresql-jdbc-java package were installed using the commands given below,

$ sudo dpkg-query -l | grep libpostgresql-jdbc-java *

You will get with libpostgresql-jdbc-java package name, version, architecture and description in a table

libpostgresql-jdbc-java package basic information: