Regarding Java switch statements - using return and omitting breaks in each case

Question

Given this method  does this represent some egregious stylistic or semantic faux pas   private double translateSlider int sliderVal        switch  sliderVal            case 0              return 1 0          case 1              return  9          case 2              return  8          case 3              return  7          case 4              return  6          default              return 1 0              It s clearly not in line with the Java tutorials here     However  It s clear  concise and so far has yielded exactly what I need   Is there a compelling  pragmatic reason to create a local variable  assign a value to it within each case  add a break to each case and return the value at the end of the method

User · Answer

Best case for human logic to computer generated bytecode would be to utilize code like the following:

private double translateSlider(int sliderVal) {
  float retval = 1.0;

  switch (sliderVal) {
    case 1: retval = 0.9; break;
    case 2: retval = 0.8; break;
    case 3: retval = 0.7; break;
    case 4: retval = 0.6; break;
    case 0:
    default: break;
  }
  return retval;
}

Thus eliminating multiple exits from the method and utilizing the language logically. (ie while sliderVal is an integer range of 1-4 change float value else if sliderVal is 0 and all other values, retval stays the same float value of 1.0)

However something like this with each integer value of sliderVal being (n-(n/10)) one really could just do a lambda and get a faster results:

private double translateSlider = (int sliderVal) -> (1.0-(siderVal/10));

Edit: A modulus of 4 may be in order to keep logic (ie (n-(n/10))%4))

User · Answer

I suggest you not use literals   Other than that the style itself looks fine

User · Answer

From human intelligence view your code is fine  From static code analysis tools view there are multiple returns  which makes it harder to debug  e g you cannot set one and only breakpoint immediately before return  Further you would not hard code the 4 slider steps in an professional app  Either calculate the values by using max - min  etc   or look them up in an array  public static final double   SLIDER VALUES    1 0  0 9  0 8  0 7  0 6   public static final double SLIDER DEFAULT   1 0    private double translateSlider int sliderValue      double result   SLIDER DEFAULT    if  sliderValue  gt   0  amp  amp  sliderValue  lt  SLIDER VALUES length          ret   SLIDER VALUES sliderValue          return result

User · Answer

I think that what you have written is perfectly fine  I also don t see any readability issue with having multiple return statements   I would always prefer to return from the point in the code when I know to return and this will avoid running logic below the return   There can be an argument for having a single return point for debugging and logging  But  in your code  there is no issue of debugging and logging if we use it  It is very simple and readable the way you wrote

User · Answer

Assigning a value to a local variable and then returning that at the end is considered a good practice  Methods having multiple exits are harder to debug and can be difficult to read   That said  thats the only plus point left to this paradigm  It was originated when only low-level procedural languages were around  And it made much more sense at that time   While we are on the topic you must check this out  Its an interesting read

User · Answer

Nope  what you have is fine  You could also do this as a formula  sliderVal  lt  5    1 0 - 0 1   sliderVal    1 0  or use a Map lt Integer Double gt   but what you have is fine

User · Answer

Yes this is good  Tutorials are not always consize and neat  Not only that  creating local variables is waste of space and inefficient

User · Answer

Why not just   private double translateSlider int sliderval    if sliderval  gt  4    sliderval  lt  0      return 1 0d  return  1 0d -   double sliderval 10 0d        Or similar

User · Answer

If you re going to have a method that just runs the switch and then returns some value  then sure this way works   But if you want a switch with other stuff in a method then you can t use return or the rest of the code inside the method will not execute   Notice in the tutorial how it has a print after the code  Yours would not be able to do this

User · Answer

Though the question is old enough it still can be referenced nowdays  Semantically that is exactly what Java 12 introduced  https   openjdk java net jeps 325   thus  exactly in that simple example provided I can t see any problem or cons

[java] Regarding Java switch statements - using return and omitting breaks in each case

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