关于“调用类中的static final常量时并不会触发该类的初始化，但是调用接口中的static final常量时便会触发该接口的初始化 ”的否定

系统管理员 2023-06-16 07:58 13阅读 0赞

1、调用运行期常量，接口和类都会触发初始化:
    public class MyTest1 {
        public static void main(String[] args) {
    
            System.out.println(Child.b);
            System.out.println(ChildClass.b);
        }
    }
    
    interface Parent {
        public static String a = "Hello World";
    
    }
    
    interface Child extends Parent {
    //    public static final String b = "childinterface b";
        public static final String b = UUID.randomUUID().toString();
        public static final Thread thread = new Thread(){
            {
                System.out.println("childinterface thread invoked");
            }
        };
    }
    
    
    class ChildClass{
    //    public static final String b = "ChildClass b ";
        public static final String b = UUID.randomUUID().toString();
        public static final Thread thread = new Thread(){
            {
                System.out.println("childClass thread invoked");
            }
        };
    }

运行结果如下，

childinterface thread invoked  
1f078d18-96f1-4b30-9b26-eba86bcdd417  
childClass thread invoked  
f9ef3a83-26ed-4ce0-ae46-1a22b5264a24

2.调用编译器常量，都不会触发类或接口的初始化（因为已经放入调用类的常量池中）

public class MyTest1 {
        public static void main(String[] args) {
    
            System.out.println(Child.b);
            System.out.println(ChildClass.b);
        }
    }
    
    interface Parent {
        public static String a = "Hello World";
    
    }
    
    interface Child extends Parent {
        public static final String b = "childinterface b";
    //    public static final String b = UUID.randomUUID().toString();
        public static final Thread thread = new Thread(){
            {
                System.out.println("childinterface thread invoked");
            }
        };
    }
    
    
    class ChildClass{
        public static final String b = "ChildClass b ";
    //    public static final String b = UUID.randomUUID().toString();
        public static final Thread thread = new Thread(){
            {
                System.out.println("childClass thread invoked");
            }
        };
    }

运行结果：

childinterface b  
ChildClass b