Java 嵌套 if to switch 语句

Question

I'm having trouble transforming the following nested if statement below, into an equivalent switch statement. If anyone can give me some advice, it would be appreciated.

if (num1 == 5)
    myChar = ‘A’;
else
if (num1 == 6 )
    myChar = ‘B’;
else
if (num1 = 7)
    myChar = ‘C’;
else
    myChar = ‘D’;

Answer 1

Pretty straightforward, just use the number as the thing you want to switch on. Your else case becomes the default case.

switch (num1) {
    case 5:
        myChar = 'A';
        break;
    case 6:
        myChar = 'B';
        break;
    case 7:
        myChar = 'C';
        break;
    default:
        myChar = 'D';
        break;
}

Answer 2

For more details chek the documentation : https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html

switch(num1){
 case 5:
   myChar = ‘A’;
   break;
 case 6:
   myChar = ‘B’;
   break;
 case 7:
   myChar = ‘C’;
   break;
 default:
   myChar = ‘D’;
}

Answer 3

If the values follow a simple pattern like this, you don't need a switch at all. For example you can do

myChar = num1 >= 5 && num1 <= 7 ? (char) ('A' + num1 - 5) : 'D';

If num1 is always 5 , 6 , 7 or 8 you can just do

myChar = (char) ('A' + num1 - 5);

Answer 4

In JDK 12, extended switch will allow you to assign a char value directly to the switch. Construct your switch as such:

char myChar = switch(num1) {
    case 5 -> 'A';
    case 6 -> 'B'; 
    case 7 -> 'C';
    default -> 'D';
}