Java中泛型使用

泛型作用：

泛型：集合类添加对象不用强转

反射机制：将泛型固定的类的所有方法和成员全部显示出来

核心代码：

ArrayList<Ls> ff=new ArrayList()<Ls>;

Ls ls1=new Ls(“薯片”,5f);

ff.add(ls1);

Ls cls=ff.get(0);//这里不再需要强转

代码实例：

说明：这是非泛型的代码，集合类中调用对象时需要强转

import java.util.*;

public class L4_6

{

public static void main(String[] args)

{

//Hashtable ff=new Hashtable();

ArrayList ff=new ArrayList();

Ls ls1=new Ls(“薯片”,5f);

ff.add(ls1);

Ls cls=(Ls)ff.get(0);

Yl hyl=(Yl)ff.get(0);//这样显然是不对的

}

}

class Ls

{

private String mingcheng;

private float jiage;

Ls(String mingcheng,float jiage)

{

this.mingcheng=mingcheng;

this.jiage=jiage;

}

}

class Yl

{

private String mingcheng;

private float jiage;

private String yanse;

Yl(String mingcheng,float jiage,String yanse)

{

this.mingcheng=mingcheng;

this.jiage=jiage;

this.yanse=yanse;

}

}