After Android imports a project, a red exclamation point is returned or a red exclamation point is returned when eclipse is restarted.

1. When importing a new Android project, a red exclamation point appears on the project name,ProgramCannot run.

Cause 1: the package path pointed to in classpath in the project is incorrect.

Solution: Right-click the project name and select properties, and then select JavaBulid
The libraries option in path, where the path marked with red X is the Error Path. After deletion, addExternalAdd the correct path in jars, click OK, and then click package
Explorer.

Cause 2: The project SDK you imported does not match your own SDK.

Solution: Right-click to modify your SDK path.