findViewById在罐子内返回null

Question

I have a small piece of code that works correctly in its own project (it is just a file selection dialog). I wanted to use it in my larger project, so I exported the FileSelector as a jar by doing the following:

• Right click on the FileSelector project and click 'Export'

• Select Java -> JAR file

• Set the 'export destination'

• Click 'Finish'

• Copy the exported .jar file into MyProject/libs

• Right click on MyProject -> Refresh

• Right click on MyProject -> Properties

• Click 'Java Build Path'

• In the 'Libraries' tab, click "Add JARs" and select the .jar file I just copied into MyProject

I was getting the error "Error generating final archive: Found duplicate file for APK: AndroidManifest.xml", so I just unselected AndroidManifest.xml from the list of files to export to the jar and created it again.

MyProject seems to build fine, but when I run it and click the button that should display the file selection dialog, I get a null pointer exception. I went back and tracked it down in the FileSelection code, and it is a simple

mFilterSpinner = (Spinner) mDialog.findViewById(R.id.fileFilter);

that is returning null. Is there something I have not done in the project setup that will allow a call like this to work from inside a jar? Or is there something wrong with my procedure for packaging up and importing the jar?

Answer 1

Values in R class would be modified. So, you can't find your view when using compiled R inside your Jar.

The only solution is using android library project and reference resources and sources through it. Otherwise, you can referencing it by making your android library project into AAR archive.

Answer 2

如果您使用的是Android UI组件，我认为您应该在另一个项目中将其用作Android库。