张龙JVM001中的Singleton

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package com.zeph.jvm1;public class Singleton {private static Singleton singleton = new Singleton();public static int a;public static int b = 0;private Singleton() {a++;b++;}public static Singleton getSingleton() {return singleton;}public static void main(String[] args) {Singleton singleton = Singleton.getSingleton();System.out.println(singleton.a);System.out.println(singleton.b);}}

输出1和0，调用类的静态方法，主动加载类，但尚未初始化，然后初始化，首先初始化new Singleton（），此时a=1，b=1，然后初始化b=0，于是输出1和0

package com.zeph.jvm1;public class Singleton {public static int a;public static int b = 0;private static Singleton singleton = new Singleton();private Singleton() {a++;b++;}public static Singleton getSingleton() {return singleton;}public static void main(String[] args) {Singleton singleton = Singleton.getSingleton();System.out.println(singleton.a);System.out.println(singleton.b);}}

输出1和1
反之，最后初始化newSingleton，所以是1和1