【正文】 object visit invokes through the function invocation, between the object all intermunion are invoke through the method invocation, By object data encapsulation, enhances reuse rate very much.. OOP the most important thought is class, the class is the template ,is a blueprint, construct an object from a class, namely construct an instance of the class. 3. Encapsulation: is that bines the data and the behavior in a package) and hides the data the realization process to the object user, in an object data is called its instance field. expands a class to obtain a new class is called inheritance, but all classes are constructed by the object super root class of expansion, super root class of as follows can make the introduction. 3 principal characteristics Behavior explained this object can make what. Tate when the object exerts the method object reflection. Dentity and other similar behavior objects discrimination symbols. Each object has only indentity and among three characteristics they affect mutually. 6. Relations among classes: Usea:Dependent relation Hasa:Polymerization relation Isa: inheritor relation example:A class has inherited B class, this time A class not only has B class of method, but also has its own method(Individuality exists in general character) object use structure:Structure proposing, the structure is one special method, the structure object and to its initialization. Example:A Data class of structure calls Data New Data () structure a new object, also initialize current time. Data happyday=new Data () an object evaluates an variable happyday, thus enables this object to be used many times, here be stated the cause variable and the object variable are different. New returns the value is a quotation. Constructor characteristic:The constructor may have 0, one or many parameters The constructor and the class have the same name A class 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 dynami