Constructors, member variables, local variables

     * 变量作用域：变量按照其所在的位置,可以分为成员变量（全局变量）、局部变量两大类
     * 
     * 成员变量：
     *         作用类中其它结构外的变量,
     *         成员变量的作用范围是整个类中都可以使用（在静态方法中不能使用非静态的成员变量,可以使用静态的成员变量）
     *         成员变量系统会给它赋值一个默认值
     *         在同一个类中,不能有同名的全局变量,全局变量和局部变量可以同名,在使用的时候,局部变量具有更高的优先级
     * 局部变量：
     *         作用方法中或者其它结构内的变量,
     *         局部变量的作用范围只限于定义局部变量的结构中
     *         局部变量没有默认值,在使用之前要进行赋值,否则会报错
     *         在不同的方法内（获取其它结构内）可以有相同名称的局部变量,在同一个方法或者结构内不能有同名的局部变量

package cn.bdqn.demo06;

public class Demo01 {

	String name;
	//String name;
	int num1 = 1000;
	
	public void test(){
		int num1;
		System.out.println(name);
		num1 = 100;
		//局部变量在使用之前一定要赋值
		System.out.println(num1);
	}
	
	public void demo(){
		//System.out.println(num1);
		int num1 =100;
		System.out.println(num1);
	}
	
	public static void ttt(){
		//Static methods can't use a static member variables in
//		System.out.println(name);
	}

	public static void main(String[] args) {
		for (int i = 1; i <= 10; i++) {
			System.out.println(i);
		}

		// System.out.println(i);
		// System.out.println(name);
		
		//创建Demo01对象
		Demo01 d = new Demo01();
		d.test();
	}

}

     * 方法重载：在同一个类中,出现多个方法的方法名相同,参数列表不同（参数的个数、参数的类型、参数顺序）的现象.
     *     1）在同一个类中
     *     2）方法名相同
     *  3）参数列表不同
     *  4）与返回值类型、访问权限修饰符无关

package cn.bdqn.demo04;

public class Dog {
	
	// 定义属性
	String name;
	int age;
	String gender;
	String color;
	String brand;
	String weight;

	
	public Dog() {
	}

	public Dog(String name, int age, String gender) {
		
		this.name = name;
		this.age = age;
		this.gender = gender;
		
	}

	public Dog(String name, int age, String gender, String color, String brand,
			String weight) {

		this.name = name;
		this.age = age;
		this.gender = gender;
		this.color = color;
		this.brand = brand;
		this.weight = weight;
	}
	
	//定义几个普通方法
	public int sum(int num1,int num2){
		return num1+num2;
	}
	
	public double sum(double num1,double num2){
		return num1+num2;
	}
	
	public double sum(int num1,double num2){
		return num1+num2;
	}
	
	public double sum(double num1,int num2){
		return num1+num2;
	}
	
	public int sum(int num1,int num2,int num3){
		return num1+num2+num3;
	}
	
	public void test(){
		System.out.println("test()");
	}
	
	public void demo(){
		this.test();
	}

}

package cn.bdqn.demo05;

public class Penguin {
	String name;
	int health;
	String sex;

	//注意：This method is not a constructor,Only the method name not in accordance with the specification name,The method name is the name of the class
	public void  Penguin() {
		health = 10;
		sex = "雄";
		System.out.println("执行构造方法");
	}

	public void print() {
		System.out.println("企鹅的名字是" + name + ",健康值是" + health + ",性别是" + sex);
	}

	public static void main(String[] args) {
		/*
		 * The first partyPenguin()Is the default constructor refs,The default no arguments constructor method didn't do any operation in the body
		 * 所以,By default arguments constructor to create objects,All attributes of the object attribute values are default values.
		 * The default value of integer types are0,The default value of floating point Numbers are0.0,boolean类型的默认值是false,charType the default value is blank,引用数据类型默认值是null
		 */
		Penguin pgn3= new Penguin();
		pgn3.print();

		
	}
}

package cn.bdqn.demo01;

public class Student {
	
	//定义属性
	String name;
	int age;
	char gender;
	
	//定义方法
	public void printInfo(){
		System.out.println("姓名："+name);
		System.out.println("年龄："+age);
		System.out.println("性别："+gender);
	}

}

package cn.bdqn.demo03;

public class StudentTest {

	public static void main(String[] args) {
		//使用Student类里的无参构造函数创建对象
		Student stu = new Student();
		//给对象属性赋值
		stu.name = "张三";
		stu.age = 22;
		stu.gender = '男';
		stu.height = 170;
		stu.weight = 140;
		stu.address = "安徽合肥";
		stu.phoneNumber = 13012341234L;
		stu.score = 99.5;
		stu.printInfo();
		
		
		//The above properties of the object is a an assignment,比较麻烦,能不能在创建对象的时候一次性赋值？--》通过有参构造函数来实现
		Student stu2 = new Student("李四", 21, '男', 175.5, 135.8, "安徽安庆", 98.5, 13878784646L);
		stu2.printInfo();
		
		
		
		
	}

}

package cn.bdqn.demo03;

public class Teacher {
	String name;
	int age;
	char gender;
	double height;
	double weight;
	String address;
	double score;
	long phoneNumber;
	
	
	//添加无参构造方法
	public Teacher() {

	}

	//添加有参构造方法
	public Teacher(String name, int age, char gender, double height,
			double weight, String address, double score, long phoneNumber) {
		this.name = name;
		this.age = age;
		this.gender = gender;
		this.height = height;
		this.weight = weight;
		this.address = address;
		this.score = score;
		this.phoneNumber = phoneNumber;
	}
	
	
	
}

package cn.bdqn.demo03;

public class TeacherTest {

	public static void main(String[] args) {
		Teacher teacher = new Teacher("王五", 22, '男', 189, 165, "安徽淮北", 89.5, 13888889999L);

	}

}

package cn.bdqn.demo07;

public class Test {
	public int num;

	public void calc(int num, int num2) {
		System.out.println(num + num2);
	}

	public static void main(String[] args) {
		Test test = new Test();
		test.num = 10;
		test.calc(11, 3);//14
		System.out.println(test.num);//10
	}

}