1) ************************************

import java.util.List;

class A {
static String foo(List<Integer> l) {return null;}
}

class B extends A {
static Integer foo(List<Integer> l) {return null;}
}

/usr/local/home/maurizio/Desktop/Test3.java:8: foo(java.util.List<java.lang.Integer>) in B cannot override foo(java.util.List<java.lang.Integer>) in A; attempting to use incompatible return type
         Integer foo(List<Integer> l) {return null;}
                 ^
  required: java.lang.String
  found: java.lang.Integer
1 error

(2) ************************************

import java.util.List;

class A {
static String foo(List<Integer> l) {return null;}
}

class B extends A {
static Integer foo(List<String> l) {return null;}
}

Test3.java:8: name clash: foo(java.util.List<java.lang.String>) in B and foo(java.util.List<java.lang.Integer>) in A have the same erasure, yet neither overrides the other
static int foo(List<String> l) {return 0;}
^
1 error