错误弹窗如图：
Installation failed with message Failed to finalize session: INSTALL_FAILED_TEST_ONLY:installPackageLI.
It is possible that this issue is resolved by uninstalling an existing version of the apk if it is present, and then re-installing.
WARNING: Uninstalling will remove the application data!
Do you want to uninstall the existing application?
1.Clean Project之后再试，如果还不行就在模拟器上面卸载该app。
2解决方法：
1、打开菜单File——Settings——Build,Execution,Deployment——Instant Run
2、不选中Enable Instant Run to hot swap code/resource changes on deploy(default enabled)
3、依次点击Apply——OK，重新运行程序，大功告成。
我使用第一种方式，完美的解决了我自己的问题。