illegal combination of modifiers: abstract and static

An abstract method cannot be static because the abstract method must be overridden i.e, body of the abstract method must be defined before invocation.

See the wrong code below:

public abstract class Employee
{
public static abstract double earnings(); // error
}

Here the abstract method earnings() is declared as static. An abstract method must be non-static. So the correct code is:

public abstract class Employee
{
public abstract double earnings(); // no error now
}