Question

how can I create simple matrix for String that could be contains following combinations

123456 ABC    
123456AB1
123456AB12
123456AB123
123456

for example

if ("\\d + \\d + \\d + \\d + \\d + \\d  
   + \\s 
   + [a-zA-Z]+[a-zA-Z]+[a-zA-Z]") {
   //passed variant from input in form 123456 ABC

} else if ("\\d + \\d + \\d + \\d + \\d + \\d 
   + [a-zA-Z]+[a-zA-Z]+[a-zA-Z]
   + \\d") {
   //passed variant from input in form 123456AB1

} else if ("\\d + \\d + \\d + \\d + \\d + \\d 
   + [a-zA-Z]+[a-zA-Z]+[a-zA-Z]
   + \\d + \\d") {
   //passed variant from input in form 123456AB12

} else if ("\\d + \\d + \\d + \\d + \\d + \\d 
   + [a-zA-Z]+[a-zA-Z]+[a-zA-Z]
   + \\d + \\d + \\d") {
   //passed variant from input in form 123456AB123

} else if ("\\d + \\d + \\d + \\d + \\d + \\d") {
   //passed variant from input in form 0123456

} else {
   //doesn't match
}

Answer 1

You could for instance use the following regexs

123456 ABC  -> \\d{6}\\s\\w{3}
123456AB1   -> \\d{6}\\w{3}
123456AB12  -> \\d{6}\\w{4}
123456AB123 -> \\d{6}\\w{5}
123456      -> \\d{6}

The if-clauses can be used as in your example, e.g.,

if(str.matches("\\d{6}\\s\\w+") { 
    ... 
} ...

Just as your question, these regex variants only covers the exact combinations from this example.