Android emulator created the first project encountered problems

Appcompat_v7 is Google's own compatibility package, which is a support library that allows Android2.1 to use the 4.0 version of the interface.

Solution One: regardless of the existence of APPCOMPAT_V7, directly do their own projects.

Workaround Two:

Accidentally remove the appcompat_v7, then appear the small Red Fork fork.

Click "Project" on the menu bar, select "Clean", then "OK", and when clean is complete, you will find the APPCOMPAT_V7 package error. The problem with the red warning in the test package has been resolved, except that the test package has a yellow warning, just because the import class in Test's Java file is not being used, so it is completely out of control.
If it does not work, then right-click the test project, select Properties, check the "islibrary" box under the Library, click "OK", then follow the steps above to perform "clean" operation.

Solution Three: since the APPCOMPAT_V7 package is a can let more than 2.1 of the full use of the 4.0 version of the interface of the support library, then we build the project directly to the minimum SDK selected above Android4.0 do not need this support library? The result proves that our idea is right.

　　APPCOMPAT_V7 and create the project always have a small red fork, with the first two methods are not solved, only the third solves my problem, the remaining two I do not know how the effect, I am self-study only myself slowly groping.

Android emulator created the first project encountered problems