单例模式简介

//单列 饿汉式
public class SingleDemo1
{
    private static SingleDemo1 demo1=new SingleDemo1();
    
    private  List list=new ArrayList();
    
    public SingleDemo1(){}
    public SingleDemo1(List list){
        this.list=list;
    }
    
    static SingleDemo1 getInstance() {
        return demo1;
    }
    public List getList()
    {
        return list;
    }
    public void setList(List list)
    {
        this.list = list;
    }
}

//存贮数据 像应用系统提供实列
public class Demo2
{
    private void getSig(){
        List list = new ArrayList();
        list.add("1");
        list.add("2");
        SingleDemo1 demo1=SingleDemo1.getInstance();
        demo1.setList(list);
    }
    
    public static void main(String[] args)
    {
        Demo2 demo2=new Demo2();
        demo2.getSig();
        
        SingleDemo1 demo1=SingleDemo1.getInstance();
        System.out.println(demo1.getList().size());
    }
}