Java单利模式

/**
 * 解决内存中只有一个内存空间的对象
 * 对象唯一
 * 为了避免其他程序过多的建立该类的对象，先禁止其他程序建立对象，
 * 还为了让其他程序 能访问该对象，在本类中自定义一个对象
 * 对外提供访问方式
 * 
 * 
 * */

class Single{
    private int num;
    private String name;
    
    public int getNum() {
        return num;
    }
    public void setNum(int num) {
        this.num = num;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    private static Single s = null;
    private Single(){}
    public static Single getInstance(){
        if(s==null)
            s = new Single();
        return s;
    }
}


/*
class Single{
    private Single(){
    }
    private int num;
    private String name;
    
    public int getNum() {
        return num;
    }
    public void setNum(int num) {
        this.num = num;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    private  static  Single  s = new Single();
    public static Single getInstance(){
        return s;
    }
}
*/

public class singleDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Single ss = Single.getInstance();
        Single sss = Single.getInstance();
        ss.setNum(40);
        System.out.println(sss.getNum());
        sss.setName("zhang");
        System.out.println(ss.getName());
    }

}