标签：
1.使用泛型方法可以取代将整个类泛型话，要定义泛型方法，只需将泛型参数列表至于返回值之前：public class GenericMethods {
public <T> void f(T x) {
System.out.println(x.getClass().getName());
}
public static void main(String[] args) {
GenericMethods gm = new GenericMethods();
gm.f("");
gm.f(1);
gm.f(1.0);
gm.f(1.0F);
gm.f('c');
gm.f(gm);
}
}public class GenericVarargs {
public static <T> List<T> makeList(T... args) {
List<T> result = new ArrayList<T>();
for (T item : args)
result.add(item);
return result;
}
public static void main(String[] args) {
List<String> ls = makeList("A");
System.out.println(ls);
ls = makeList("A", "B", "C");
System.out.println(ls);
ls = makeList("ABCDEFFHIJKLMNOPQRSTUVWXYZ".split(""));
System.out.println(ls);
}
}3.边界使你可以在用于泛型的参数类型上设置限制条件。public class GenericsAndCovariance {
public static void main(String[] args) {
List<? extends Fruit> flist = new ArrayList<Apple>();
// Compile Error: can't add any type of object:
// flist.add(new Apple());
// flist.add(new Fruit());
// flist.add(new Object());
flist.add(null); // Legal but uninteresting
// We know that it returns at least Fruit:
Fruit f = flist.get(0);
}
}5.<? super T>这里比较容易使用，没<? extends T>这么多限制，这里的意思是，以T类为下限的某种类，标签：
原文地址：http://blog.csdn.net/zdp072/article/details/44024981
