Using switch statement with a range of value in each case

Question

In Java  is it possible to write a switch statement where each case contains more than one value  For example  though clearly the following code won t work    switch  num        case 1    5          System out println  testing case 1 to 5            break      case 6    10          System out println  testing case 6 to 10            break      I think this can be done in Objective C  are there a similar thing in Java  Or should I just use if  else if statements instead

User · Answer

case 1  case 2  case 3  case 4  case 5            System out println  testing case 1 to 5             break    case 6  case 7  case 8  case 9  case 10           System out println  testing case 6 to 10             break    default           System out println  default

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Try this if you must use switch   public static int range int num        if   10  lt  num  amp  amp  num  lt  20          return 1      if   20  lt   num  amp  amp  num  lt  30          return 2      return 3     public static final int TEN TWENTY   1  public static final int TWENTY THIRTY   2   public static void main String  args       int a   110      switch  range a            case TEN TWENTY               System out println  10-20                 break          case TWENTY THIRTY               System out println  20-30                 break          default  break

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It s possible to group several conditions in the same case statement using the mechanism of fall through allowed by switch statements  it s mentioned in the Java tutorial and fully specified in section   14 11  The switch Statement of the Java Language Specification   The following snippet of code was taken from an example in the tutorial  it calculates the number of days in each month  numbered from month 1 to month 12    switch  month        case 1  case 3  case 5      case 7  case 8  case 10      case 12          numDays   31          break      case 4  case 6      case 9  case 11          numDays   30          break      case 2          if    year   4    0   amp  amp                  year   100    0                    year   400    0               numDays   29          else             numDays   28          break      default          System out println  Invalid month             break      As you can see  for covering a range of values in a single case statement the only alternative is to list each of the possible values individually  one after the other  As an additional example  here s how to implement the pseudocode in the question   switch num        case 1  case 2  case 3  case 4  case 5          System out println  testing case 1 to 5            break      case 6  case 7  case 8  case 9  case 10          System out println  testing case 6 to 10            break

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For input number in range 0  100  int n1   75     input value String res  int n 0   int   a   0 20 35 55 70 85 101    for   n1 gt  a n   n     switch 6-n 1      case 1  res  A   break    case 2  res  B   break    case 3  res  C   break    case 4  res  D   break    case 5  res  E   break    default res  F     System out println res

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other alternative is using math operation by dividing it  for example   switch   int  num 10        case 1          System out println  10-19            break      case 2          System out println  20-29            break      case 3          System out println  30-39            break      case 4          System out println  40-49            break      default          break      But  as you can see this can only be used when the range is fixed in each case

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Use a NavigableMap implementation  like TreeMap      Setup    NavigableMap lt Integer  Optional lt String gt  gt  messages   new TreeMap lt  gt     messages put Integer MIN VALUE  Optional empty     messages put 1  Optional of  testing case 1 to 5     messages put 6  Optional of  testing case 6 to 10     messages put 11  Optional empty         Use    messages floorEntry 3  getValue   ifPresent System out  println

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The closest you can get to that kind of behavior with switch statements is  switch  num    case 1  case 2  case 3  case 4  case 5       System out println  1 through 5         break  case 6  case 7  case 8  case 9  case 10       System out println  6 through 10         break      Use if statements

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You could use an enum to represent your ranges    public static enum IntRange     ONE TO FIVE  SIX TO TEN    public boolean isInRange int v        switch  this        case ONE TO FIVE        return  v  gt   1  amp  amp  v  lt   5       case SIX TO TEN        return  v  gt   6  amp  amp  v  lt   10             return false         public static IntRange getValue int v        if  v  gt   1  amp  amp  v  lt   5          return ONE TO FIVE        else if  v  gt   6  amp  amp  v  lt   10          return SIX TO TEN            return null

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missingfaktor  s answer is indeed correct but a bit over-complicated  Code is more verbose  at least for continuous intervals  then it could be  and requires overloads casts and or parameterization for long  float  Integer etc  if  num  lt  1      System Out Println  invalid case      num      you should verify that anyway else if  num  lt   5      System Out Println  1 to 5    else if  num  lt   10      System Out Println  6 to 10    else if  num  lt   42      System Out Println  11 to 42    else         System Out Println  43 to  infinity

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I know this post is old but I believe this answer deserves some recognition  There is no need to avoid the switch statement  This can be done in java but through the switch statement  not the cases  It involves using ternary operators    public class Solution        public static void main String   args            Scanner sc   new Scanner System in           int num   Integer parseInt sc nextLine              switch   1  lt   num  amp  amp  num  lt   5     0                    6  lt   num  amp  amp  num  lt   10    1   2                 case 0                  System out println  I m between one and five inclusive                     break              case 1                  System out println  I m between 6 and 10 inclusive                     break              case 2                  System out println  I m not between one and five or 6 and 10 inclusive                     break

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It is supported as of Java 12  Check out JEP 354  No  range  possibilities here  but can be useful either   switch  day        case MONDAY  FRIDAY  SUNDAY - gt  System out println 6    number of letters     case TUESDAY                - gt  System out println 7       case THURSDAY  SATURDAY     - gt  System out println 8       case WEDNESDAY              - gt  System out println 9       You should be able to implement that on ints too  Note through that your switch statement have to be exhaustive  using default keyword  or using all possible values in case statements

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Java has nothing of that sort  Why not just do the following   public static boolean isBetween int x  int lower  int upper      return lower  lt   x  amp  amp  x  lt   upper     if  isBetween num  1  5       System out println  testing case 1 to 5      else if  isBetween num  6  10       System out println  testing case 6 to 10

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No you can t do that  The best you can do is that   case 1  case 2  case 3  case 4  case 5     System Out Println  testing case 1 to 5    break

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Or you could use your solo cases as intended and use your default case to specify range instructions as    switch n        case 1   System out println  case 1    break      case 4   System out println  case 4    break      case 99   System out println  case 99    break      default           if  n  gt   10  amp  amp  n  lt   15              System out println  10-15 range             else if  n  gt   100  amp  amp  n  lt   200              System out println  100-200 range            else             System out println  Your default case            break

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This type of behavior is not supported in Java  However  if you have a large project that needs this  consider blending in Groovy code in your project  Groovy code is compiled into byte code and can be run with JVM  The company I work for uses Groovy to write service classes and Java to write everything else

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I don t think you can do that in Java  Best bet is to just put the code in the last case of the range   switch  num      case 1  case 2  case 3  case 4  case 5        System Out Println  testing case 1 to 5         break    case 6  case 7  case 8  case 9  case 10       System Out Println  testing case 6 to 10         break    default

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Here is a beautiful and minimalist way to go  num  gt  1  amp  amp  num  lt  5    first case method                           System out println  quot testing case 1 to 5 quot                           num  gt  5  amp  amp  num  lt  7     System out println  quot testing case 5 to 7 quot                            num  gt  7  amp  amp  num  lt  8     System out println  quot testing case 7 to 8 quot                            num  gt  8  amp  amp  num  lt  9     System out println  quot testing case 8 to 9 quot                                                       System out println  quot default quot

[java] Using switch statement with a range of value in each case?

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