饿汉式
public class Singleton{
private static volatile Singleton instance = new Singleton();
private Singleton(){}
public static Singleton getInstance() {
return instance;
}
}
懒汉式
public class Singleton{
private static Singleton instance；
private Singleton(){}
public static Singleton getInstance() {
if(instance == null){
intance = new Singleton():
}
return instance;
}
}
双重检测
public class Singleton {
private static volatile Singleton instance = null;
private Singleton() {
}
public static Singleton getInstance() {
if (instance == null) {
synchronized (Singleton.class) {
if (instance == null) {
instance = new Singleton();
}
}
}
return instance;
}
}
静态内部类
class Singleton{
private static class SingletonDemo{
private final static Singleton INSTANCE = new Singleton();
}
private Singleton(){}
private static final Singleton getInstance() {
return SingletonDemo.INSTANCE;
}
}
枚举类
public enum Singleton{
INSTANCE;
public void instance(){}
}
