Comparing chars in Java

Question

I want to check a char variable is one of 21 specific chars  what is the shortest way I can do this   For example   if symbol      A   B   C        Doesn t seem to be working  Do I need to write it like   if symbol     A     symbol     B  etc

User · Accepted Answer

If your input is a character and the characters you are checking against are mostly consecutive you could try this:

if ((symbol >= 'A' && symbol <= 'Z') || symbol == '?') {
    // ...
}

However if your input is a string a more compact approach (but slower) is to use a regular expression with a character class:

if (symbol.matches("[A-Z?]")) {
    // ...
}

If you have a character you'll first need to convert it to a string before you can use a regular expression:

if (Character.toString(symbol).matches("[A-Z?]")) {
    // ...
}

User · Answer

Yes  you need to write it like your second line   Java doesn t have the python style syntactic sugar of your first line   Alternatively you could put your valid values into an array and check for the existence of symbol in the array

User · Answer

Option 2 will work   You could also use a Set lt Character gt  or  char   myCharSet   new char     A    B    C         Arrays sort myCharSet   if  Arrays binarySearch myCharSet  symbol   gt   0

User · Answer

The first statement you have is probably not what you want     A   B   C  is actually doing bitwise operation     Your second statement is correct  but you will have 21 ORs   If the 21 characters are  consecutive  the above solutions is fine   If not you can pre-compute a hash set of valid characters and do something like   if  validCharHashSet contains symbol

User · Answer

you can use this   if   ABCDEFGHIJKLMNOPQRSTUVWXYZ  contains String valueOf yourChar      note that you do not need to create a separate String with the letters A-Z

User · Answer

If you know all your 21 characters in advance you can write them all as one String and then check it like this   char wanted    x   String candidates    abcdefghij      boolean hit   candidates indexOf wanted   gt   0    I think this is the shortest way

User · Answer

pseudocode as I haven t got a java sdk on me   Char candidates   new Char      A    B        G      foreach Char c in candidates        if  symbol    c    return true      return false

User · Answer

Using Guava   if  CharMatcher anyOf  ABC      matches symbol             Or if many of those characters are a range  such as  A  to  U  but some aren t   CharMatcher inRange  A    U   or CharMatcher anyOf  1379      You can also declare this as a static final field so the matcher doesn t have to be created each time   private static final CharMatcher MATCHER   CharMatcher anyOf  ABC

User · Answer

It might be clearer written as a switch statement with fall through e g   switch  symbol       case  A       case  B            Do stuff       break       default

User · Answer

One way to do it using a List lt Character gt  constructed using overloaded convenience factory methods in java9 is as    if List of  A   B   C   D   E   contains symbol           do something

User · Answer

If you have specific chars should be   Collection lt Character gt  specificChars   Arrays asList  A    D    E        more chars char symbol    Y   System out println specificChars contains symbol         false symbol    A   System out println specificChars contains symbol         true

User · Answer

You can just write your chars as Strings and use the equals method   For Example   String firstChar    A   String secondChar    B   String thirdChar    C    if  firstChar equalsIgnoreCase secondChar              firstChar equalsIgnoreCase thirdChar       As many equals as you want       System out println firstChar     is the same as     secondChar     else       System out println firstChar     is different than     secondChar

[java] Comparing chars in Java

Examples related to java

Examples related to comparison

Examples related to char