2021-02-18 java单例模式

public class SingletonObject {

    private static volatile SingletonObject instance;

    private SingletonObject() {
    }

    public static SingletonObject getInstance() {
        if (instance == null) {
            synchronized (SingletonObject.class) {
                if (instance == null) {
                    instance = new SingletonObject();
                }
            }
        }
        return instance;
    }
}