java enum class example

parent class. As in the example above, "int x = 2;" Change to "static int x = 2;", then compile and run the program and get the following resultMethod overridesIf a subclass does not need to use the functionality of a method inherited from a parent class, you can declare your own method, called a method override, with the same name. The return type of the overri

Yesterday, when the written test encountered the creation of the internal class of Java and access to the problem, I do not understand, did not write, so today up deliberately to test, there is this summary of the article. Inner classes in Java are also classified as non-static inner classes (anonymous inner classes are also non-static inner classes) and st

When it comes to the Tomcat class loading mechanism, we have to say that translation learns Tomcat's original purpose. Before the internship time to learn javamelody source, but it is a MAVEN project, and our own Web project integration can not be directly debugging breakpoints. Later colleague guidance, said that the Java class is directly copied to the SRC

summarize the load time of a class by saying that the class is loaded when any of its static members are accessed.7. ArraysThe initialization of an array can use a special expression, as follows:Int[] A = {1,2,3,4,5};Note: In this case, the allocation of the storage space will be the responsibility of the compiler. This approach is allocated in heap space (equivalent to using new) rather than stack space,

Functions and categories of class loaders As the name suggests, the class loader is used to load classes into JVM. The JVM Specification defines two types of class loaders: start class loader (bootstrap) and user-defined loader (user-defined class loader ). Bootstrap is a

(); } System.out.println (C1 = = C3); try {//To create an instance object of the class with the class type of the class foo C4 = (foo) c1.newinstance (); C4.start (); catch (Instantiationexception e) {e.printstacktrace (); catch (Illegalaccessexception e) {e.printstacktrace (); Class foo{p

{ Public Static voidMain (string[] args) {Long x1=NewLong (100);//Manual BoxingLong x2 = 100L;//Automatic Boxing Longx3 = x2;//Automatic Unpacking Longx4 = X1.longvalue ();//Manual UnpackingString S1= "123456"; intD1 =Integer.parseint (S1); Integer D2=integer.valueof (S1); System.out.println (D1+" "+D2); Integer W1=NewInteger (100); Integer W2=NewInteger (100); SYSTEM.OUT.PRINTLN (W1==W2);//falseInteger W3 =-128; Integer W4=-128; System.out.println (W3==W4);//true//when an integer

Class classes are implementations that define a particular class in the Java language. The definition of a class contains the member variables, the member methods, the interfaces that the class implements, and the parent class of

Recalling Java memoirs (2): Java 02 class and object, Java 02 Class: subjective abstraction. Object Templates Can be instantiated into objects-defining a template, which cannot be directly used. --- To use classes, you must create them as objects. -- Abstract The actual obj

converted, and String. valueOf (Object. These methods are analyzed one by one. Method 1: Use the Object # toString () method. See the following example: Object object = getObject (); System. out. PRintln (object. toString (); in this method, Because java. lang. the public method already exists in the Object class. toString (), so this method can be called for an

and automatic unpacking. Automatic boxing/unboxing greatly facilitates the use of basic types of data and their wrapper classes. 　　Automatic Boxing : The basic type is automatically converted into a packing class (int >> Integer) 　　Automatic unboxing : Packing class automatically converted to basic type (Integer >> int) For example, the following examples: Imp

Directory Class Loader Dynamic loading Link Initialization Example Class LoaderBefore you understand the mechanics of Java, you need to understand how the class is loaded in the JVM (the Java Virtual

? Not_create_mongo_collection:create_mongo_collection_such + string.join (",", collections); }catch (Exception e) {e.printstacktrace (); Logger.error (create_mongo_collection_exception); } return null; }/** * Get mongocollection * @param mongoclient * @param dbName * @param collection * @return * * Public mongocollection　　MONGO used to define the comparison constantspublic enum Mongoconst { GT ("$gt"), LT (

extended classpath by including a portal named Class-path (which contains a list of files and directories). JDK 1.3 introduces the Class-path manifest portal for specifying optional jar files and directories that can be loaded as needed. Here is an example of a Class-path entry: