商苑面馆：Java程序开发基础

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任务二 JAVA程序开发基础

2.1变量和表达式

  • Java控制台输入：
import java.util.Scanner; 
 
public class Test {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        // 从键盘接收数据
 
        // next方式接收字符串
        System.out.println("next方式接收：");
               
        String str1 = scan.next();
        String str2 = "刀削面";
        if(str1.equals(str2)){
        	System.out.println("您选择的是：" + str1);     
        }
           
        scan.close();
    }
}

2.2智能决策：选择结构

三目运算符

package demo1;
import java.util.Scanner;
public class happy08 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//int a = 10 ;int b = 20;
		//System.out.println(a==b);
		Scanner sc = new Scanner(System.in);
		System.out.println("客官，您是堂吃还是外卖？1.堂吃； 2.外卖");
		String s = sc.next();
		String s2 = (s.equals("1")) ? "堂吃一位" : "外送一位";
		System.out.println(s2);

	}

}

if条件语句

第一种形式： 

public class Hello123 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		// TODO Auto-generated method stub
		float mian = 10.0f;//面的价格
		float suan = 2.0f;//酸梅汤
		float total_pay =0f;//总钱数
		Scanner sc = new Scanner(System.in);
		//问用户要几碗面？
		System.out.println("请问您要几碗面？");
		int num = sc.nextInt();
		total_pay = num * mian;
		        
		 //问顾客需不需要饮料（饮料2元一杯）
		
		 System.out.println("请问您是否需要饮料？Y/n");
		 String s = sc.next( );
		 if( s.equals("y")){
			 total_pay = total_pay + num * suan;
		 }
		 
		 System.out.printf("您一共消费了%f元",total_pay);
		 sc.close();
	}

}

第2种形式： 

package demo1;
import java.util.Scanner;
public class Tangchi {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        System.out.println("客官，请问您是堂吃还是外送？"
        		+"1.堂吃/2.外送");
        String s = sc.next();
        if(s.equals("1")){
        	System.out.println("堂吃一位！");
        }else{
        	System.out.println("外送一位！");
        }
	}

}

第3种形式： 

package demo1;
import java.util.Scanner;
public class MianType {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        System.out.println("客官，您几位？");
        int num = sc.nextInt();
        System.out.println("请问你们吃什么面？");
        System.out.println("a.老北京炸酱面;b.刀削面"
        		          +"c.油泼面");
        String s = sc.next();
        if(s.equals("a")){
        	System.out.printf("老北京炸酱面%d碗",num);
        }else if(s.equals("b")){
        	System.out.printf("刀削面%d碗",num);
        }else if(s.equals("c")){
        	System.out.printf("油泼面%d碗",num);
        }else{
        	System.out.println("不好意思，您需求的面我们这里没有");
        
        }
	}

}


if语句的嵌套

询问顾客吃什么面，并询问其是否加蛋、加油渣 ？将结果反馈给后台。

if语句的多条件

import java.util.Scanner;
public class happy09 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
        float price ;boolean fenqi;boolean firstpay;
        System.out.println("老板，请问手机多少钱？");
        Scanner sc = new Scanner(System.in);
        price = sc.nextFloat();
        System.out.println("老板，请问支不支持分期?");
        fenqi = sc.nextBoolean();
        System.out.println("老板，请问支不支持零首付?");
        firstpay = sc.nextBoolean();
        
        if(price <=1000 && fenqi == true && firstpay == true) {
        	System.out.println("小Case!");
        }else {
        	System.out.println("太贵了，买不起~");
        }
	}

}

switch语句

package test;
import java.util.Scanner;
public class a7 {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Scanner sc = new Scanner (System.in);
		while (true){
		System.out.println("客观，请问您需要什么面：");
		System.out.print("1.刀削面\n2.蛋黄面\n3.玉米面\n4.牛筋面\n5.幸福小丸仔面\n");
		int m = sc.nextInt();
		switch (m){
		case 1:
			System.out.println("您选择的是刀削面");
			break;
		case 2:
			System.out.println("您选择的是蛋黄面");
			break;
		case 3:
			System.out.println("您选择的是玉米面");
			break;
		case 4:
			System.out.println("您选择的是牛筋面");
			break;
		case 5:
			System.out.println("您选择的是幸福小丸仔面");
			break;
		default:
			System.out.println("对不起 输入错误");
			break;
		}
		}

	}

}

2.3重复迭代：循环结构

while循环

package test;
import java.util.Scanner;
public class a7 {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Scanner sc = new Scanner (System.in);
		while (true){
		  System.out.println("客观，请问您需要什么面：");
		  System.out.print("1.刀削面\n2.蛋黄面\n3.玉米面\n4.牛筋面\n5.幸福小丸仔面\n");
		  int m = sc.nextInt();
		  switch (m){
		     case 1:
			System.out.println("您选择的是刀削面");
			break;
		     case 2:
			System.out.println("您选择的是蛋黄面");
			break;
		     case 3:
			System.out.println("您选择的是玉米面");
			break;
		     case 4:
			System.out.println("您选择的是牛筋面");
			break;
		     case 5:
			System.out.println("您选择的是幸福小丸仔面");
			break;
		     default:
			System.out.println("对不起 输入错误");
			break;
		 }
		}

	}

}

for循环

public class test02 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
        //String a ="hello";
		String [] menu = {"阳春面","油泼面","鸡汤面","火鸡面","安徽板面"};
		for(int i=0;i <5;i++){
			System.out.println(menu[i]);
		}
		
	}

}

循环的嵌套

public class test03 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String [] menu = {"阳春面","油泼面","鸡汤面","火鸡面","安徽板面"};
		String [] drink = {"可乐","啤酒","雪碧"};
		for(int i=0;i<5;i++){
			for(int j=0;j<3;j++){
				System.out.println(menu[i]+"+"+drink[j]);
			}
		}
	}

}

2.4 数据的存储--数组

Java一维数组

  • 面馆老板现在需要重新定义一份菜单，使用一维数组，他有几种方法呢 ？
public class HelloWorld {
    public static void main(String []args) {
       //System.out.println("Hello World!");
	   String menu = new String[5];
	   menu[0] = "炸酱面";
	   menu[1] = "刀削面";
	   menu[2] = "安徽板面";
	   menu[3] = "葱油拌面";
	   menu[4] = "兰州拉面";
	   
	   
	  
    }
}

Java二维数组

  • 面馆老板现在需要根据周一到周五，每天推出三款特价面，利用二维数组，他该怎么做呢 ？

public class erweishuzu {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//double [][] priec = new double [4] [3];
		String [][] price = {{"炸酱面","方便面","版面"},{"刀削面","拉面","炒面"},{"牛肉面","鸡汤面","红烧面"},{"炒面","拉面","刀削面"},{"牛肉面","红烧面","鸡汤面"}};
		
		for(int i=0;i<5;i++) {
			System.out.println("周"+(i+1));
			for(int j = 0;j<3;j++) {
				System.out.println(price[i][j]);
			}	
		}
	}

}

Javva for语句循环遍历数组

  • 面馆老板用foreach语句遍历打印每一种面。 






					

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