Android requires compiler compliance level 5.0 or 6.0. Found '1.7' instead. Please use Android Tools > Fix Project Properties

In order to fix this error:

1. Go to the Properties for your project (double click on your project), then find out Adroid Tools/Project Properties (see screenshot)

2. Then change Compile Compiance level to the higher level e.g 1.5 or 1.6 (That is it :) )