What is the usages and advantages on using static imports?
Static import allows you to import static variables from other classes (usually, these variables should be constants).
Thus, it provides a simplifed way for you to access the contants. In the past, you need to use package.class.X to access the constant X which defined in package.class, and if there are 10 constants, you need to refer specify each variable with package.class, which is very trouble.
Now, just as classes, you can import those objects statically. However, it turns out some issues that, if class1 and class2 define the constant with the same name, there will be ambigourity if your class need to access both classes.