3的值為true執行程式碼

}else{

//如果以上布林表示式都不為true執行程式碼

}

public static void main(String[] args) {
  //考試分數大於60就是及格，小於60就不及格
  Scanner scanner = new Scanner(System.in);
​
  System.out.println("請輸入成績");
  double score = scanner.nextDouble();
​
  if (score==100){
    System.out.println("恭喜滿分");
   }else if (score>=90&&score<100){
    System.out.println("A級");
   }else if (score>=80&&score<90){
    System.out.println("B級");
   }else if (score>=70&&score<80){
    System.out.println("C級");
   }else if (score>=60&&score<70){
    System.out.println("D級");
   }else if (score>100||score<0){
    System.out.println("成績有誤");
   }else{
    System.out.println("不及格");
​
   }
​
  scanner.close();
}
 

switch

case穿透：如果沒有default程式會一直往下執行

public static void main(String[] args) {
  //case穿透
  char grade = 'C';
​
  switch (grade){
    case 'A':
      System.out.println("優秀");
    case 'B':
      System.out.println("良好");
    case 'C':
      System.out.println("及格");
    case 'D':
      System.out.println("再接再厲");
    default:
      System.out.println("未知等級");
​
​
   }
}
 

public static void main(String[] args) {
//case穿透
char grade = 'C';

switch (grade){
case 'A':
System.out.println("優秀");
break;
case 'B':
System.out.println("良好");
break;
case 'C':
System.out.println("及格");
break;
case 'D':
System.out.println("再接再厲");
break;
default:
System.out.println("未知等級");


}
}