Java (if else)(switch case)结构

package Z1;

import java.util.Scanner;

public class Test3 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入会员号");
int a = sc.nextInt();
System.out.println("请输入会员生日:（格式为月/日，例如：01/05）");
String b = sc.next();
System.out.println("请输入会员积分:");
double c = sc.nextDouble();
if (b.length() != 4 && b.indexOf('.') != -1) {
// indexOf:返回指定字符在此字符串中第一次出现处的索引。
System.out.println("会员生日输入错误");
} else if (a < 1000 || a > 9999) {
System.out.println("会员号输入错误");
} else if (c < 100) {
System.out.println("会员积分过低，请及时充值");
} else {
System.out.println(a + "\\t" + b + "\\t" + c);
}
}
}

import java.util.Scanner;

public class Test5 {

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("请输入年龄：");
int i = input.nextInt();
System.out.println("请输入性别：");
String j = input.next();
switch (i) {
case 1:
case 2:
case 3:
case 4:
System.out
4000
.println("搬不动。");
break;
case 5:
if (j.charAt(0) == '男') {
System.out.println("可以搬动桌子。");
} else {
System.out.println("搬不动。");
}
break;
case 6:
if (j.charAt(0) == '男') {
System.out.println("可以搬动桌子。");
} else {
System.out.println("搬不动。");
}
break;
default:
System.out.println("可以搬动桌子。");

}
}
}

③：迷你计算器

import java.util.Scanner;

public class Test7 {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

System.out.println("请输入第一个数");

double a = sc.nextDouble();

System.out.println("请输入第二个数");

double b = sc.nextDouble();

System.out.println("请输入运算符");

String c = sc.next();

double d = 0;

switch (c.charAt(0)) {

case '+':

d = a + b;
System.out.println(d);
break;

case '-':

d = a - b;
System.out.println(d);
break;

case '*':

d = a * b;
System.out.println(d);
break;

case '/':

d = a / b;
System.out.println(d);
break;

default:

System.out.println("输入运算符错误");
break;

}
}
}