昨日回顾

编程竞赛

题目
1，小明点了3个菜，花了60元，用Java描述

//Dish.java

public class Dish {
	private String dishName;
	private int money;
	
	public String getDishName() {
		return dishName;
	}
	public void setDishName(String dishName) {
		this.dishName = dishName;
	}
	public int getMoney() {
		return money;
	}
	public void setMoney(int money) {
		this.money = money;
	}
}

//Person

public class Person {
	private String personName;
	
	public String getPersonName() {
		return personName;
	}

	public void setPersonName(String personName) {
		this.personName = personName;
	}
	
	//方法 点菜
	void order(Person p1,Dish d1,Dish d2,Dish d3) {
		System.out.print(p1.personName+"点了"+d1.getDishName()+","+d2.getDishName()+","+d3.getDishName()+"三个菜,");
	}
	
	//方法 付钱
	void pay(Dish d1,Dish d2,Dish d3) {
		System.out.println("花了"+(d1.getMoney()+d2.getMoney()+d3.getMoney())+"块钱.");
	}
}

//Test

public class Test {
	public static void main(String[] args) {
		Person p1 = new Person();
		p1.setPersonName("小明");
		
		Dish d1 = new Dish();
		d1.setDishName("番茄炒蛋");
		d1.setMoney(18);
		Dish d2 = new Dish();
		d2.setDishName("青椒肉丝");
		d2.setMoney(25);
		Dish d3 = new Dish();
		d3.setDishName("麻婆豆腐");
		d3.setMoney(17);
		
		p1.order(p1, d1, d2, d3);
		p1.pay(d1, d2, d3);
	}
}

2，写一个array list，存入3个char类型的数据，4个double类型数据，然后通过for循环，把里面所以元素打印。

import java.util.ArrayList;

public class ArrayListDemo {
	public static void main(String[] args) {
		ArrayList ls = new ArrayList();
		
		//3个char类型数据
		System.out.println("3个char类型数据,随机取ASCII可显示字符:");
		for(int i = 0;i<3;i++) {
			ls.add((char)(Math.random()*94+32));
			System.out.print(ls.get(i)+" ");
		}
		
		//4个double类型数据
		System.out.println();
		System.out.println();
		System.out.println("4个double类型数据,[0,1)区间随机数:");
		for(int i = 3;i<7;i++) {
			ls.add(Math.random());
			System.out.print(ls.get(i)+", ");
		}

	}
}

结对作业

1，小明转账1000元给小红，Java描述

//Person.java

public class Person {
	private String personName;
	private int balance;//余额
	public String getPersonName() {
		return personName;
	}
	public void setPersonName(String personName) {
		this.personName = personName;
	}
	public int getBalance() {
		return balance;
	}
	public void setBalance(int balance) {
		this.balance = balance;
	}
	
	void transfer( Person p1,Person p2,TransferAmount m1) {
		System.out.println(p1.personName+"原来有"+p1.balance+"元,"+p2.personName+"原来有"+p2.balance+"元.");
		p1.balance -= m1.getTransferAmount();
		p2.balance += m1.getTransferAmount();
		System.out.println(p1.personName+"给"+p2.personName+"转账"+m1.getTransferAmount()+"元.");
		System.out.println(p1.personName+"余额"+p1.balance+"元,"+p2.personName+"余额"+p2.balance+"元.");
	}
}

//TransferAmount.java

//转账金额
public class TransferAmount {
	private int transferAmount;

	public int getTransferAmount() {
		return transferAmount;
	}

	public void setTransferAmount(int transferAmount) {
		this.transferAmount = transferAmount;
	}
}

Test.java

public class Test {
	public static void main(String[] args) {
		Person p1 = new Person();
		p1.setPersonName("小明");
		p1.setBalance(3000);//小明余额3000
		Person p2 = new Person();
		p2.setPersonName("小红");
		p2.setBalance(500);//小红余额500
		
		TransferAmount m1 = new TransferAmount();
		m1.setTransferAmount(1000);//转账金额1000
		
		p1.transfer(p1, p2, m1);
	}
}

2，写一个三维数组，存12个int 数据，打印可以被三整除的数据

public class ThreeDArray12Int {
	public static void main(String[] args) {
		int a [][][] = new int[2][3][2];
		//一个三维数组，存12个int 数据
		System.out.println("存放12个int型数据的三维数组打印结果:");
		for(int i =0;i<a.length;i++) {
			for(int j =0;j<a[i].length;j++) {
				for(int k =0;k<a[i][j].length;k++) {
					//使用随机数填充数组
					a[i][j][k] = (int)(Math.random()*100);
					System.out.print(a[i][j][k]+" ");
				}
				System.out.println();
			}
			System.out.println();
		}
		
		//打印能被3整除的数
		System.out.println("其中能被3整除的数有:");
		for(int i =0;i<a.length;i++) {
			for(int j =0;j<a[i].length;j++) {
				for(int k =0;k<a[i][j].length;k++) {
					if(a[i][j][k]%3 == 0) {
						System.out.print(a[i][j][k]+" ");
					}
				}
			}
		}
	}
}

上课内容

1.判断是否相等

基本数据类型(8种 byte short int long float double char boolean),用 == 判断.
引用类型变量,用 equals 方法.

2.安装dbeaver进行数据库管理

show databases;//显示所有数据库

创建一个表
CREATE TABLE java9.`user` (
	name varchar(100) NULL,
	pwd varchar(100) NULL
)
ENGINE=InnoDB
DEFAULT CHARSET=utf8
COLLATE=utf8_general_ci ;

插入条数据

insert into user (name,pwd) values ('小李','888');

查询用户表的所有数据
select * from user;

修改小明的密码，改成555
 update user set pwd='555' where name='小明';