class Gen<T> {
 private T ob;
 //定义泛型成员变量
 public Gen(T ob) {
  this.ob = ob;
 }
 public T getOb() {
  return ob;
 }
 public void setOb(T ob) {
  this.ob = ob;
 }
 public void showType() {
  System.out.println("T的实际类型是: " + ob.getClass().getName());
 }
}
public class GenericParameter {
 public static void main(String[] args){
  //定义泛型类Gen的一个Integer版本
  Gen<Integer> intOb=new Gen<Integer>(100);
  intOb.showType();
  int i= intOb.getOb();
  System.out.println("value= " + i);
  System.out.println("----------------------------------");
  //定义泛型类Gen的一个String版本
  Gen<String> strOb=new Gen<String>("Hello Dylan!");
  strOb.showType();
  String s=strOb.getOb();
  System.out.println("value= " + s);
 }
}

class GenericsFoo<T> {
 private T x;
 public GenericsFoo(T x) {
  this.x = x;
 }
 public T getX() {
  return x;
 }
 public void setX(T x) {
  this.x = x;
 }
}
public class GenericClass {
 public static void main(String args[]){
  GenericsFoo<String> strFoo=new GenericsFoo<String>("Hello Generics!");
  GenericsFoo<double> douFoo=new GenericsFoo<double>(new double("33"));
  GenericsFoo<Object> objFoo=new GenericsFoo<Object>(new Object());
  System.out.println("strFoo.getX="+strFoo.getX());
  System.out.println("douFoo.getX="+douFoo.getX());
  System.out.println("objFoo.getX="+objFoo.getX());
 }
}

import java.util.ArrayList;
import java.util.Collection;
class CollectionGenFoo<T extends Collection> {
 private T x;
 public CollectionGenFoo(T x) {
  this.x = x;
 }
 public T getX() {
  return x;
 }
 public void setX(T x) {
  this.x = x;
 }
}
public class GenericRestrict {
 public static void main(String[] args) {
  CollectionGenFoo<ArrayList> listFoo = null;
  listFoo = new CollectionGenFoo<ArrayList>(new ArrayList());
  CollectionGenFoo<? extends Collection> listFoo1 = null;
  listFoo1=new CollectionGenFoo<ArrayList>(new ArrayList());
  System.out.println("实例化成功!");
 }
}

public class GenericFunction {
 public <T> void f(T x) {
  System.out.println(x.getClass().getName());
 }
 public static void main(String[] args) {
  GenericFunction ea = new GenericFunction();
  ea.f(" ");
  ea.f(10);
  ea.f('a');
  ea.f(ea);
 }
}