import java.util.List; import java.util.Map; class ExtensionMethodGeneric { public void test() { List<String> stringList = null; List<Number> numberList = null; ExtensionMethodGeneric.Extensions.test(stringList); ExtensionMethodGeneric.Extensions.test(stringList, numberList); ExtensionMethodGeneric.Extensions.test(ExtensionMethodGeneric.Extensions.test(stringList, stringList), numberList); Integer i = ExtensionMethodGeneric.Extensions.test2(stringList); Map<String, Integer> map = null; List<String> l = ExtensionMethodGeneric.Extensions.test(map, stringList, numberList); } static class Extensions { public static <T> List<T> test(List<String> obj, List<T> list) { return null; } public static <K, V> K test(Map<String, Integer> obj, K k, V v) { return k; } public static <T> T test(List<T> list) { return null; } public static <T, U> U test2(List<T> list) { return null; } } }