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public class SingleObject {        private static SingleObject instance = new SingleObject();        private SingleObject() {        }        public static SingleObject getInstance() {            return instance;        }        public void showMessage() {            System.out.println("?????????" + instance);        }    }

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public class SingletonPatternDemo {        public static void main(String[] args) {            for (int i = 0; i < 3; i++) {                SingleObject instance = SingleObject.getInstance();                instance.showMessage();            }        }    }

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com.freedom.pattern.singleton.SingleObject@47089e5f  com.freedom.pattern.singleton.SingleObject@47089e5f  com.freedom.pattern.singleton.SingleObject@47089e5f