"Android library projects cannot be launched"?

Now I am totally confused by this error message: Android library projects cannot be launched.

I carefully checked the build path and library, everything seems "OK", and there is no error on Problems view, however, when I tried to run my application as an Android project, it failed and showed that message.

Any explanation for why it's happening is appreciated!

From Android's Developer Documentation on Managing Projects from Eclipse with ADT:

Setting up a Library Project

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

1. In the Package Explorer, right-click the library project and select Properties.
2. In the Properties window, select the "Android" properties group at left and locate the Library properties at right.
3. Select the "is Library" checkbox and click Apply.
4. Click OK to close the Properties window.

So, open your project properties, un-select the "Is Library" checkbox, and click Apply to make your project a normal Android project (not a library project).

Through the this steps you can .

1. In Eclipse , Right Click on Project from Package Explorer.
2. Select Properties,.
3. Select Android from Properties pop up window,
4. See "Is Library" check box,
5. If it is checked then Unchecked "Is Library" check box.
6. Click Apply and than OK.

With Me I had the library ticked under Eclipse>Project Properties>Android what I just did was uncheck the ticked library.

It says “Android library projects cannot be launched” because Android library projects cannot be launched. That simple. You cannot run a library. If you want to test a library, create an Android project that uses the library, and execute it.

In Eclipse Project -> Clean Modify project.properties like this :

target=android-10
android.library.reference.1=F:/svn/WiEngine_library