Java day

import java.util.Scanner; public class day_01{ public static void main(String[] args){ test1(); // 数据类型/类型转换 test2(); // 运算符 test3(); // 自增自减/比较运算符 test4(); // 短路 test5(); // if语句 test6(); // 计算闰年平年 test7(); // 交换 test8(); // 收银系统 } public static void test1(){ char ch='a'; System.out.println(ch); System.out.println(ch+1); System.out.println(ch+2); System.out.println((char)(ch+1)); System.out.println((char)(ch+2)); System.out.println((int)3.14); } public static void test2(){ int num1=3; int num2=5; int result=num1+num2; System.out.println(result); System.out.println(8/2); System.out.println(8%2); System.out.println(8/3); System.out.println(8%3); System.out.println(2/7); System.out.println(2%7); } public static void test3(){ int i=3; i++; System.out.println(i); System.out.println(i++); System.out.println(++i); System.out.println(3>=5); System.out.println(5<=10); } public static void test4(){ int num3=3; int num4=5; System.out.println(num3<0 && num3++<num4); System.out.println(num3); System.out.println(num4); System.out.println(num3>0||num3++<num4); System.out.println(num3); } public static void test5(){ Scanner scanner=new Scanner(System.in); System.out.println("请输入学生成绩:"); // 从控制台读入一个整数 int score=scanner.nextInt(); // 将非法情况过滤 if(score<0||score>100){ System.out.println("输入成绩非法!"); return; } // 遇到return,正割函数执行结束,后面代码不再执行. if(score>=90&&score<100){ System.out.println("优秀"); }else if(score>=80&&score<90){ System.out.println("良好"); }else if(score>=70&&score<80){ System.out.println("一般"); }else if(score>=60&&score<70){ System.out.println("及格"); }else{ System.out.println("不及格"); } } public static void test6(){ Scanner scanner=new Scanner(System.in); System.out.println("请输入年份:"); int year=scanner.nextInt(); if((year%4==0&&year%100!=0)||(year%400==0)){ System.out.println(year+"是闰年"); }else{ System.out.println(year+"是平年"); } } public static void test7(){ Scanner scanner=new Scanner(System.in); System.out.println("请输入第一个数:"); int num5=scanner.nextInt(); System.out.println("请输入第二个数:"); int num6=scanner.nextInt(); System.out.println(num5); System.out.println(num6); int temp=num5; num5=num6; num6=temp; System.out.println(num5); System.out.println(num6); } public static void test8(){ Scanner scanner=new Scanner(System.in); System.out.println("请输入单价:"); double danjia=scanner.nextDouble(); System.out.println("请输入数量:"); double count=scanner.nextInt(); System.out.println("请输入用户金额:"); double price=scanner.nextDouble(); // 应收金额 double totalPrice=danjia*count; if (totalPrice>=500){ totalPrice=totalPrice*0.8; } double zhaoling=price-totalPrice; if (zhaoling>0){ System.out.println("应收金额:"+totalPrice); System.out.println("找零:"+zhaoling); }else{ System.out.println("付款金额不足!"); } } }