一个类在一个系统中,从头到尾只有一个对象
范例:懒汉式
public class Singleton {
private static Singleton s;
private Singleton(){}
public synchronized static Singleton getInstance(){
if (s==null){
s=new Singleton();
}
return s;
}
}
public class TextSingleton {
public static void main(String[] args) {
Singleton s1=Singleton.getInstance();
Singleton s2=Singleton.getInstance();
System.out.println(s1);
System.out.println(s2);
System.out.println(s1==s2);
}
范例:饿汉式
public class Singleton {
private static Singleton s;
private Singleton(){}
static {
s=new Singleton();
}
public static Singleton getInstance(){
return s;
}
}