学习日志——2019/07/06

java 语言基础

• 变量的作用于域
  类体一共有两部份组成，一部分是属性的定义，一部分是方法的定义（一个类可以有多个方法）。
  类的属性就是定义在类的内部、方法的外部的变量；而定义在方法内部的变量称为局部变量。两者的作用域是不同的。属性的作用域是整个类。

eg：
package eg1;

public class Example {
	int x=0;
	int y=0;
	void method() {
		int x=1;
		System.out.println("x="+x);
		System.out.println("y="+y);
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Example e=new Example();
		e.method();
	}

}

• 类属性

package eg1;

public class Employee {
	String name;
	int age ;
	double salary;
	public Employee() {
		name ="小明";
		age=32;
		salary=3000;
	}
	public Employee(String n,int a,double s) {
		name=n;
		age=a;
		salary=s;
	}
	void raise(double p) {
		salary=salary+p;
		System.out.println(name+"涨工资之后的工资为："+salary);
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Employee e1=new Employee();
		e1.name="王一";
		e1.salary=1600;
		e1.raise(100);
		Employee e2=new Employee("张敏",29,3000);
		e2.raise(500);
	}
}

• 类与对象的使用
  eg：

public class Example {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//声明对象并分配内存
		People 张三=new People("张华",20);
		People 李四= new People("自由职业者",true);
		People 无名=new People();
		
	}

}
class People{
	String name,career;
	boolean sex=true;	//true代表女，false代表男
	int age;
	double height;
	public People(String name,int age) {//从姓名、年龄角度分析People类时使用
		this.name=name;
		this.age=age;
		System.out.println("姓名："+name+"年龄："+age);
	}
	public People(String career,boolean sex) {
		this.career=career;//从性别、职业角度分析People类时使用
		this.sex=sex;
		System.out.println("职业："+career+"性别："+sex);
	}
	public People() {
		System.out.println(sex);
	}
}

• Telephone类的编写和应用

public class Example01 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Telephone tel;
		tel=new Telephone("TCL","84515",100);
		tel.rate=0.2;
		tel.dialledTime=150;
		tel.diaplay();
		tel.recharge(50);
		
	}	
		
}
	class Telephone{
		String brand ;
		String number;
		double dialledTime;
		double rate;
		double balance;
		public Telephone(String brand,String number,double balance ) {
			this.brand=brand;
			this.number=number ;
			this.balance=balance;
			
		}
		public void recharge(double cost) {
			balance  = balance+cost;
			System.out.println("充值后的余额："+balance );
			
		}
		public void callCost() {
			double callcost=dialledTime * rate;
			balance=balance-callcost;
			System.out.println("话费："+callcost);
			System.out.println("余额："+balance);
			
		}
		public void diaplay() {
			System.out.println("电话品牌："+brand+"电话号码："+number);
			System.out.println("通话时间："+dialledTime+"费率："+rate);
			
		}
	}