Constant expression required in switch statement

Question

I want to use global constants in a switch statement. I wrote the constants in a Singleton called ColorManager in this way

public static final int blue = 3;
public static final int red = 5;
public static final int black = 7;

in my HomeActivity I wrote this code

public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    ColorManager cm = ColorManager.getInstance(this);
    switch (requestCode) {
        case cm.blue: {
        }
        case cm.red: {
        }
        case cm.black: {
        }
    }
}

But I get an error in the switch statement:

Constant expression required

The values are final so constant, I don't understand why I get this error. I found similar topics but in all cases the properties was not declared as final.

there is no constant keyword in java. Final does not mean constant — Tim, Oct 05 '16 at 09:41
read this http://stackoverflow.com/questions/3827393/java-switch-statement-constant-expression-required-but-it-is-constant — Pavneet_Singh, Oct 05 '16 at 09:42
There's no need to put curly brackets (`{` and `}`) around `case` block. You should either use `break;` or `return` from exiting the case. If you don't do that, the commands under the next `case` will be executed. — Sufian, Oct 05 '16 at 09:54

score 3 · Accepted Answer · answered Oct 05 '16 at 09:45

3

It will compile if you access your static final fields statically; e.g. case ColorManager.blue:. If you try and access then from a variable cm, then you're preventing the compiler recognising them as compile-time constants.

answered Oct 05 '16 at 09:45

khelwood

55,782
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score 0 · Answer 2 · answered Oct 05 '16 at 09:45

0

Use ClassName.variable i.e ColorManager.red

answered Oct 05 '16 at 09:45

Shuddh

1,920
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score 0 · Answer 3 · answered Oct 05 '16 at 09:55

Try this code

public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {

    switch (requestCode) {
        case ColorManager.blue: {
        }
        case ColorManager.red: {
        }
        case ColorManager.black: {
        }
    }
}

Constant expression required in switch statement

3 Answers3