java中generic实例详解

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);
	}
}