Why is this switch case not working in Netbeans?

问题

Switch case is taking value but only the default case is running.

int z = Integer.parseInt(x);
JOptionPane.showMessageDialog(null,+z);
    switch (z) {
    case ('1'):
        C.SetEmpInformation();
        break;
    case ('2'):
        C.UpdateEmpInformation();
        break;
    default:
        JOptionPane.showMessageDialog(null, "Invalid Identity");
}

回答1:

Remove the single quotes in your case statements. They will be matched as char and not as int. '1' is a character and very different from the number 1.

 switch (z) {
   case 1: /* .... */
   case 2: /* .... */
   default : /* .... */
}

You wouldn't need the brackets as well.

回答2:

The type you are checking in your case statements is wrong, you compare an int (z) to a char ('1').

You need to write your cases like this:

JOptionPane.showMessageDialog(null, + z); // btw, what is this + doing here?
    switch (z) {
    case 1:
        C.SetEmpInformation();
        break;
    case 2:
        C.UpdateEmpInformation();
        break;
    default:
        JOptionPane.showMessageDialog(null, "Invalid Identity");
        break;
}

回答3:

It works for me in NetBeans too, so if it does not even start on your machine, you may have some verification tool, linter, something like that.
Anyway, what you write is correct Java code, just probably it will not do what you expect, and that is what the message may indicate.
You can switch on numbers, characters and Strings, all of them work. Just do not mix them: they either will not compile (mixing numbers/characters with String), or will work in a probably unexpected way (mixing numbers with characters), because 1 is a number but '1' is a character, which is represented by its ASCII code as a number, 49.

Test code:

String x="1";
int z=Integer.parseInt(x);
switch(z){
  case ('1'): System.out.println(z+" is '1'");break;
  default: System.out.println(z+" is not '1'");
}

x="49";
z=Integer.parseInt(x);
switch(z){
  case ('1'): System.out.println(z+" is '1'");break;
  default: System.out.println(z+" is not '1'");
}

x="1";
z=Integer.parseInt(x);
switch(z){
  case 1: System.out.println(z+" is 1");break;
  default: System.out.println(z+" is not 1");
}

switch(x.charAt(0)){
  case '1': System.out.println("\"1\".charAt(0) is '1'");break;
  default: System.out.println("\"1\".charAt(0) is not '1'");
}

switch(x){
  case "1": System.out.println("\""+x+"\" is \"1\"");break;
  default: System.out.println("\""+x+"\" is not \"1\"");
}

Output:

1 is not '1'
49 is '1'
1 is 1
"1".charAt(0) is '1'
"1" is "1"

来源：https://stackoverflow.com/questions/52907617/why-is-this-switch-case-not-working-in-netbeans

标签

java

switch-statement