1: Two-dimensional Array (understanding)(1) The element is an array of one-dimensional arrays. (2) Format: A: Data type [] [] Array name =
new data type [m][n];B: Data type [] Array name =
new data type [m][];C: Data type [] Array name =
new data type [][]{{...},{...},{...}};D: Data type [] Array name =
{{...},{...},{...}};
Note the differences defined below:
int[] x,y[]; equivalent to
int[] x; int[] y[];(3) Case (Master): A: Two-dimensional array traversal B: Sum of two-dimensional arrays C: Yang Hui triangles
two-dimensional array format 2 ( {{...}},{...},{...}; ) in memory plots
two-dimensional array format 3 (new data type [m][]; ) in memory plots
2: Two study Questions (understanding)(1) Parameter passing problem in Java only value is passed in Java. Basic type: The change of formal parameter does not affect the actual parameter reference type: The change of formal parameter directly affects the actual parameter (2) The small case of data encryption problem synthesis.
diagram of parameter passing problem in Java
3: Object-oriented (mastering) (1) Object-oriented object-oriented is a process-oriented programming idea process-oriented: Emphasizing the steps of each feature object-oriented: Emphasizing the object and then invoking the function by the object (2) object-oriented thought characteristics A: A thought that is more in line with our thinking habits B: Simplifying complex things C: Let's turn from performer to conductor example: buy computer wash clothes Cooking ... All objects (3) Putting elephants into refrigerators (understanding) A: Process-oriented B: Object-oriented implementation Note: How to make our operations more consistent with object-oriented thinking? A: What are the classes B: What are the members of each class C: Class-to-Class relationships (4) Classes and Objects class: is a set of related properties and behaviors. is an abstract concept. object: Is the concrete manifestation of this kind of thing. Specific existence of the individual. A: Things in the real world Properties Basic description Behavioral functions B:java the most basic unit of the language is the class. So, we're going to use classes to represent things C: Classes member variables things properties Member methods thing behavior D: class: Is a set of related properties and behaviors. is an abstract concept. object: is the concrete existence of this kind of thing, is a concrete example. (object) Example: Student: Class Squad Leader: Object (5) class definition and use A: class definition member variable The definition format is the same as before, where the location is different, in the class, outside the method. Member method definition The format is the same as before, which is to remove the static. B: Use the contents of the class a: Create an object? Format Class name Object name = new class name (); b: How to use member variables and member methods Object name. Member variables object names. Member method () (6) Case: A: definition and use of student class B: Definition and use of mobile phone class (7) memory diagram A: Memory diagram of an object B: Memory diagram of two objects C: Memory diagram of three objects (8) Java program Development, design, and features A: development: Is the creation of objects, through the object call function B: Design: is to manage and maintain the relationship between objects C: Features a: encapsulation b: Inheritance c: polymorphic
Java Basic Course Learning notes (6)
