Add jars, add external jars, add library, add Class folder differences

 Add External jars = Add package external to project 
 Add jars = Add Project inside package 
 Add library = Add a library 
 Add Class folder = Add a class folders 
 
 Add ja R means adding jars from your project, provided that you have placed the jar in your project directory. The 
 Add external jar indicates that the location of the jar needs to be  "to URI  to locate, you need to give the full path. The 
 Add Library is a collection of already defined jars, because they are often used together, so it simplifies operations, such as when you do RCP development there is a plugin library that contains the basic plugins needed to run the project. 
 Add Classes Loader--Should this be an Add Class folder? This is the meaning of adding a jar, which is to tell ClassLoader where to look for the class 
 add jar and add external jars and the user libraries in the Add Library are: 
 through the "Add Jar" and " Add external jars "added jar package is packaged as part of the program into the final program. The jar package that was added via "User Libraries" is not. 
 correctly import third-party jar packages in Android 
 The correct method is as follows:   
 1, right-click Project-->build path-->java Build Path, 
 2, select Libraries in the right button click "Add Library"   
 3, select "User Library", click "Next"   
 4, click the "User Librarys" button in the interface that appears. New: " button, click on the "OK" button in the pop-up screen,   
 5, click "Add jars" to select the third-party jar package and click "OK" to complete the operation. In this case, the jar package will be packaged together into the APK 

Add jars, Add external jars, add library, add class folder differences