if 判断
package operator;
public class demo08 {
public static void main(String[] args) {
// grade(成绩)
int grade = 100;
// 单选择结构
if (grade<60){
System.out.println("不及格");
}
// 双选择结构
if (grade<60){
System.out.println("不及格");
}else {
System.out.println("及格");
}
// 多选择结构
if (grade<60){
System.out.println("不及格");
}else if (grade>=60 && grade<=100){
System.out.println("及格");
}else if (grade>=80 && grade<=100){
System.out.println("卓越");
}else if (grade>=90 && grade<=100){
System.out.println("超凡");
}else {
System.out.println("成绩不合法");
}
}
}
while 循环
where 只要循环结果为true 就会一直循环
package operator;
public class demo09 {
public static void main(String[] args) {
// 计算 1 ..... 100的和
int i = 0;
int sum = 0;
while (i<=100){
sum = sum + i;
i++;
}
System.out.println(sum);
}
}
Do while循环
Do while循环条件不管你条件满不满足都会执行一次
package operator;
public class demo10 {
public static void main(String[] args) {
int i = 0;
int sum = 0;
do {
sum = sum + i;
i++;
}while (i<=100);
System.out.println(sum);
}
}
switch 判断
package operator;
public class demo11 {
public static void main(String[] args) {
int grade = 100;
// whitch 可以理解为匹配某个值， 如果不加 break，只要满足了其中一个条件，下面都会执行
switch (grade){
case 100 :
System.out.println("恭喜满分");
break;
case 80 :
System.out.println("优秀");
break;
case 60 :
System.out.println("再接再厉");
break;
default:
System.out.println("不及格");
}
}
}
