Adding a library JAR to an Eclipse Android project

Question

This is a two-part question about adding a third-party library  JAR  to an Android project in Eclipse   The first part of the question is  when I try to add a third-party JAR  library  to my Android project I first get the problem of     Error parsing XML  unbound prefix   because I m trying to use a class from that JAR  and need the prefix somehow defined   What s going on   Second   after fixing that--the answer is given below   my application doesn t work on Android and I discover via the debugger  LogCat  that the class I m attempting to consume doesn t exist      Caused by    java lang ClassNotFoundException    com github droidfu widgets WebImageView      Why  when I get no compilation or linker error in Eclipse  does it have this problem on the emulator   These two questions are rhetorical for I m going to answer them myself below  Other posts in this forum creep up to the problem and elsewhere there is discussion  but I feel that I can be more explicitly helpful for the next guy to come along

User · Answer

Setting up a Library Project

A library project is a standard Android project, so you can create a new one in the same way as you would a new application project.

When you are creating the library project, you can select any application name, package, and set other fields as needed, as shown in figure 1.

Next, set the project's properties to indicate that it is a library project:

In the Package Explorer, right-click the library project and select Properties. In the Properties window, select the "Android" properties group at left and locate the Library properties at right. Select the "is Library" checkbox and click Apply. Click OK to close the Properties window. The new project is now marked as a library project. You can begin moving source code and resources into it, as described in the sections below.

User · Answer

Ensure that your 3rd party jars are in your projects  libs  folder and they will be put in the  apk when you package your application  You may see runtime errors on the device if something in the jar is not supported  but other than that I have had great success with this

User · Answer

If you are using the ADT version 22  you need to check the android dependencies and android private libraries in the order amp Export tab in the project build path

User · Answer

First  the problem of the missing prefix   If you consume something in your layout file that comes from a third party  you may need to consume its prefix as well  something like  droidfu   which occurs in several places in the XML construct below    lt com github droidfu widgets WebImageView android id    id webimage            android layout width  75dip            android layout height  75dip            android background   CCC            droidfu autoLoad  true            droidfu imageUrl  http   www android com images opensourceprojec gif            droidfu progressDrawable                   gt    This comes out of the JAR  but you ll also need to add the new  xmlns droidfu    lt LinearLayout xmlns android  http   schemas android com apk res android        xmlns droidfu  http   github com droidfu schema            gt    or you get the unbound prefix error  For me  this was a failure to copy and paste all of the supplied example from the third-party library s pages

User · Answer

Error parsing XML  unbound prefix Resource   playteddy res  does not exist   I got the above two errors and finally I solved it  Right click your project - gt  properties - gt  java build path - gt  googleadmobadsdk  select and put it top   then you run and problem solved  It is solved my runtime error

User · Answer

Now for the missing class problem   I m an Eclipse Java EE developer and have been in the habit for many years of adding third-party libraries via the  User Library  mechanism in Build Path  Of course  there are at least 3 ways to add a third-party library  the one I use is the most elegant  in my humble opinion   This will not work  however  for Android  whose Dalvik  JVM  cannot handle an ordinary Java-compiled class  but must have it converted to a special format  This does not happen when you add a library in the way I m wont to do it   Instead  follow the  widely available  instructions for importing the third-party library  then adding it using Build Path  which makes it known to Eclipse for compilation purposes   Here is the step-by-step    Download the library to your host development system  Create a new folder  libs  in your Eclipse Android project  Right-click libs and choose Import -  General -  File System  then Next  Browse in the filesystem to find the library s parent directory  i e   where you downloaded it to   Click OK  then click the directory name  not the checkbox  in the left pane  then check the relevant JAR in the right pane  This puts the library into your project  physically   Right-click on your project  choose Build Path -  Configure Build Path  then click the Libraries tab  then Add JARs     navigate to your new JAR in the libs directory and add it   This  incidentally  is the moment at which your new JAR is converted for use on Android     NOTE  Step 5 may not be needed  if the lib is already included in your build path  Just ensure that its existence first before adding it   What you ve done here accomplishes two things    Includes a Dalvik-converted JAR in your Android project  Makes Java definitions available to Eclipse in order to find the third-party classes when developing  that is  compiling   your project s source code

User · Answer

Put the source in a folder outside yourt workspace  Rightclick in the project-explorer  and select  Import      Import the project in your workspace as an Android project  Try to build it  and make sure it is marked as a library project  Also make sure it is build with Google API support  if not you will get compile errors   Then  in right click on your main project in the project explorer  Select properties  then select Android on the left  In the library section below  click  Add     The mapview-balloons library should now be available to add to your project

User · Answer

Go to build path in eclipse  then click order and export  then check the library jar  and then click the up button to move it to the top of the list to compile it first

[android] Adding a library/JAR to an Eclipse Android project

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