Condition handling the smart way

Question

if (lineStyle == 5 || lineStyle == 21 || lineStyle == 82 || lineStyle == 83 || lineStyle == 3) {
    lineStyleString = "DOUBLE";
} else if (lineStyle == 6 || lineStyle == 35 || lineStyle == 39 || lineStyle == 30) {
    lineStyleString = "DOTTED" ;
} else if (lineStyle == 26 || lineStyle == 27  || lineStyle == 28  || lineStyle == 29 || lineStyle == 1) {
    lineStyleString = "SOLID";
} else if(lineStyle == -1) {
    lineStyleString = "NONE";
}

How do we handle this code the smart way in Java? Switch case, enum or key pair value mode?

Answer 1

Your conditions looks more random.

Switch looks good here

switch(lineStyle) {
    case 5:
    case 21:
    case 82:
    case 83:
    case 3: 
     lineStyleString = "DOUBLE";   
     break;
    .. // add more cases
}

---

Or I prefer to create utility method

public static boolean contains(int expecxted, int... vals) {
        for (int i = 0; i < vals.length; i++) {
            if (expecxted == vals[i]) {
                return true;
            }
        }
        return false;
    }

And you can use it like

if (contains(lineStyle, 5,21,82,83,3)) {
    lineStyleString = "DOUBLE";
} else if(contains(lineStyle,6,35,39,30)){
   lineStyleString = "DOTTED";
}

Answer 2

A switch case well-indented would take 30 lines (Netbeans proposed to transform it by itself so I could count)

So I would consider this way is better (9 lines) :

if (Arrays.asList(5, 21, 82, 83, 3).contains(lineStyle)) {
     lineStyleString = "DOUBLE";
} else if (Arrays.asList(6, 35, 39, 30).contains(lineStyle)) {
     lineStyleString = "DOTTED";
} else if (Arrays.asList(26, 27, 28, 29, 1).contains(lineStyle)) {
     lineStyleString = "SOLID";
}else if (lineStyle == -1) {
     lineStyleString = "NONE";
}

Answer 3

You could extract the conditions into methods to make them more readable.

private boolean isDoubleStyle(int lineStyle) {
    return lineStyle == 5 || lineStyle == 21 || lineStyle == 82 || lineStyle == 83 || lineStyle == 3;
}

private boolean isDottedStyle(int lineStyle) {
    return lineStyle == 6 || lineStyle == 35 || lineStyle == 39 || lineStyle == 30;
}

private boolean isSolidStyle(int lineStyle) {
    return lineStyle == 26 || lineStyle == 27  || lineStyle == 28  || lineStyle == 29 || lineStyle == 1;
}

and then call the methods

if (isDoubleStyle(lineStyle)) {
    lineStyleString = "DOUBLE";
} else if (isDottedStyle(lineStyle)) {
    lineStyleString = "DOTTED" ;
} else if (isSolidStyle(lineStyle)) {
    lineStyleString = "SOLID";
} else {
    lineStyleString = "NONE";
}

I removed the final check for linestyle == -1 to ensure that lineStyleString always has a value, no matter what.