I am new to java, and I am trying to build a project that has an external dependency. When I try to build it
[javac] Compiling 814 source files to ~/Desktop/Dev/bitcoinj/out
[javac] ~/Desktop/Dev/bitcoinj/src/com/google/bitcoin/core/Block.java:25: package org.slf4j does not exist
[javac] import org.slf4j.Logger;
[javac] ...
How can install the missing external package? Is there a java package manager similar to the python pip?
You could use maven which would do the dependency handling and building for you.
Dependency management is a core feature of Maven. Managing dependencies for a single project is easy. Managing dependencies for multi-module projects and applications that consist of hundreds of modules is possible. Maven helps a great deal in defining, creating, and maintaining reproducible builds with well-defined classpaths and library versions.
There's not a package manager that I know of. You're going to have to manually download the jar file -- in this case, its from http://www.slf4j.org/ . After that, you can either do as Dennis says, or add the jar file explicitly to your classpath.
You can use this site to find the .jar file: https://www.findjar.com/
Then place the file into your JRE/JDK's ext folder, e.g.: C:\Java\jdk1.8.0_201\jre\lib\ext\
To import a package: -> Download the required jar files (One of the sources for jar files is:https://jar-download.com/) -> Paste the file @ C:\Program Files\Java\jdk1.8.0_181\jre\lib\ext
