【正文】 ass may have many constructor. The constructor has not returned value The constructor always be together used with the new operator 8. Over loading: When many methods have the same name when includes the different parameter, then has the over loading Which method does the piler have to choose invokes. : Java allow one or many classes to bee together as group, is called package, to organizing duty easily, the standard Java storehouse divides into many packages java, and so on, the package is layered and all java packages are in java and in a javax package. 10. Extendable thought: permit to construct new class on existing classes , when you extend the class which already existed, then you reuse this class of method and the field, at the same time you might add the new method and the field in the new class. class:The expandable class fully manifested isa to extend the relations The form is:Class (subclass) extends (base class). 12. Multimodality: In java, the object variable is multimodality But in java does not support multiple extend. bine: the mechanism of invoking object method mechanism. 1) piler examines object statement type and method name. 2) the piler examines that method invokes parameter type. 3) static bine: If the method type is priavte static the final ,piler can accurately know which method should invoke. 4) when the procedure runs and uses dynamic bine to invoke a method, the method edition which then hypothesized machine must invoke x the object actual type which aims at to match. 5) dynamic bine: is a very important characteristic, it can cause the procedure to change again may expand but does not need to translate has saved the code. class:In order to prevent other people derive the new class from yours class, this class is cannot expanded. dynamic invocation spend longer time than the static invocation expenditure. class:Stipulated or many abstract methods class of itself must define is abstract. Example: Public abstract string getDescripition Java each class is be extended by object class. 18. equal and toString method in object class . Equal uses in testing an object is whether equal with another object. ToString returns to represent this object the string of character, each class can nearly over loading this method, in order to returns to the current condition the correct expression. (The toString method is a very important method) programming:Any class of type all values all may replace with a object class of variable. array tabulates: The ArrayList dynamic array tabulates, is a class of storehouse, defines in uitl package, but automatic control array size. class and class of object ,getclass method returns to the class type an example, when the procedure start contains can increase in the main method class, hypothesized confidential increase all classes which he needs, each increase class all must increase the class which it needs. class: class might dynamic operate the java code for the pilation the procedure to provide the formidable function reflection, this function was JavaBeans is specially useful, the use reflected Java to be able to support the VB programmer to be familiar with the use the tool. procedure of analysis class ability is called the reflector, in Java to provide this function the package to call reflect reflection mechanism is extremely formidable. 1) when run analysis class ability. 2) when run searches observes a class of object. 3) realizes the general array operation code. 4) provides the method object. But this mechanism mainly aims at the tool but not the application and the procedure. In the reflection mechanism most important part is that permits class that you inspect structure. With to API includes: returns to the field. returns to the method. returns to the parameter. Method pointer: Java does not have the method pointer, makes a method address another method, may invoke it in behind, but the interface is the better solution. 23. interface: should showing class could do what but not to assign how to do, a class may realize one or many interfaces. interface is not a class, but is to conforms to a interface request class of set of standard. If realizes a interface to need 2 steps: 1) the statement class needs to realize assigns the interface. 2) provides in the interface all methods definition. Stated a class realizes a interface to need to use the implements key words Class actionB implements Comparable its actionb needs to provide the CompareTo method, the interface is not the class, cannot use a new example interface. class only then a super class, but a class can realize many interfaces. In a Java important interface: Cloneable interface and callback :to programs a monly used pattern is callback,in the pattern, you may refer when this class of pattern settled specific time occurs re