A review of the Java object-oriented approach

1.1 Review of methods
1.1.1 Case Code One:

package com.itheima_01;/* * 需求：定义一个方法求两个数的和,并在主方法中调用 * * 方法：类中的一段具有特定功能的程序，提高了代码的复用性和可维护性 * 定义格式： * public static 返回值类型（没有返回值写void） 方法名(参数类型 参数名,参数类型 参数名2) {//形参 * 方法体; * } * 调用方式： * 有明确返回值类型： * 赋值调用，将方法的返回值赋值给一个变量 * 输出调用，使用输出语句直接输出方法的返回值 * 直接调用，没法获取方法的返回值 * 没有明确返回值类型： * 直接调用 * 方法重载：在一个类中有多个重名的方法，这些方法参数不同，和返回值无关 * * 注意： * 形参：方法声明的变量，只能是变量，接收方法调用时传递进来的数据 * 实参：调用方法时传递的数据，可以是常量也可以是变量 * */public class MethoDemo {public static void main(String[] args) {//赋值调用//int sum = sum(10,20);//实参//System.out.println(sum);//输出调用int a = 10;int b = 20;System.out.println(sum(a,b));}public static int sum(int a,int b) {/*        //使用变量接收求和结果并返回int sum = a + b;return sum;*///直接返回求和结果return a + b;}}

1.2 Review of arrays
1.2.1 Case code Two:

package com.itheima_02;/* * 需求：定义一个元素类型为int的数组，遍历数组并求和 * * 数组：用于存储多个元素的一种容器 * 数组的特点: * 元素类型必须一致 * 元素有整数索引 * 一旦定义好长度则无法改变 * 可以存储基本数据类型 * 也可以存储引用数据类型 * 定义格式： * 动态初始化 * 元素类型[] 数组名 = new 元素类型[10]; * 静态初始化 * 元素类型[] 数组名 = {元素1,元素2,元素3}; * 元素类型[] 数组名  = new 元素类型[]{元素1,元素2,元素3}; * */public class ArrayDemo {public static void main(String[] args) {//使用静态初始化定义数组int[] arr = {1,2,3,4,5};//定义一个变量用于存储求和结果int sum = 0;//遍历数组for(int x = 0;x < arr.length;x++) {sum += arr[x];}System.out.println(sum);}}

1.3 Standard class definition and usage review
1.3.1 Case Code Three:

Package com.itheima_03;/* * Defines a standard student class, creates an object in the main method and invokes * name, age, gender 3 member variable * No parameter, two constructor method * Defines a show party for each member variable defined by the Getter/setter method * method, output member variable */public class Student {private string name;//name private int age;//Age private String gender;//gender/*//non-parametric construction public Stu Dent () {}//has an argument construct public Student (String name,int age,string gender) {this.name = Name;this.age = Age;this.gender = gender;} Namepublic String GetName () {return name;} public void SetName (String name) {this.name = name;} agepublic int Getage () {return age;} public void Setage (int.) {this.age = age;} Genderpublic String Getgender () {return gender;} public void Setgender (String gender) {This.gender = gender;} *///show: Used to output all member variables public void Show () {System.out.println (name + "," + Age + "," + Gender);} Public Student () {super ();//TODO auto-generated constructor stub}public Student (string name, int age, string gender) {SUP ER (); this.name = Name;this.age = Age;this.gender = gender;} Public String GetName () {return name;} public void SetName (String name) {thiS.name = name;} public int getage () {return age;} public void Setage (int.) {this.age = age;} Public String Getgender () {return gender;} public void Setgender (String gender) {This.gender = gender;}} Package Com.itheima_03;public class Studenttest {public static void main (string[] args) {//Create student object Student s = new Student () ;//Assign value to member variable S.setname ("Zhang San"); S.setage (); S.setgender ("male"); S.show (); System.out.println ("----------"); Student s2 = new Student ("John Doe", 20, "other");//s2.show (); System.out.println (S2.getname ());}}

Review of Java object-oriented methods