java - How to create a dynamic Interface with properties file at compile time? -

the problem here property file use has insanely huge name key , of run incorrect key naming issues . got me thinking if there's way generate following interface based on property file. every change make property file auto-adjust properties interface. or there other solution?

property file

a=apple b=bannana c=cherry 

should generate following interface

interface properties{ public static final string = "a" // keys public static final string b = "b";  public static final string c = "c";   } 

so in application code

string a_value = prop.getstring(properties.a); 

there old rule programming , not it, if looks beautiful, right way do.

this approach not good, point of view.

the first thing:

do not declare constants in interfaces. violates incapsulation approach. check article please: http://en.wikipedia.org/wiki/constant_interface

the second thing:

use prefix name part of properties somehow special, let say: key_

and when load properties file, iterate on keys , extract keys name starts key_ , use values of these keys planned use constants in question.

---

update

assume, generate huge properties file upon compilation process, using our apache ant script.

for example, let's properties file (myapp.properties) looks that:

key_a = apple key_b = banana key_c = cherry anotherpropertykey1 = blablabla1 anotherpropertykey2 = blablabla2 

our special properties want handle have key names start key_ prefix.

so, write following code (please note, not optimized, proof of concept):

package propertiestest;  import java.io.fileinputstream; import java.io.filenotfoundexception; import java.io.ioexception; import java.io.inputstream; import java.util.arrays; import java.util.enumeration; import java.util.hashset; import java.util.properties; import java.util.set;   public class propertiestest {    public static void main(string[] args) throws ioexception {        final string properties_filename = "myapp.properties";               specialpropertykeysstore spkstore =                              new specialpropertykeysstore(properties_filename);         system.out.println(arrays.tostring(spkstore.getkeysarray()));     } }   class specialpropertykeysstore {      private final set<string> keys;      public specialpropertykeysstore(string propertiesfilename)                                      throws filenotfoundexception, ioexception {           // prefix of name of special property key         final string key_prefix = "key_";              properties propertieshandler = new properties();         keys = new hashset<>();      try (inputstream input = new fileinputstream(propertiesfilename)) {              propertieshandler.load(input);              enumeration<?> enumeration = propertieshandler.propertynames();             while (enumeration.hasmoreelements()) {                 string key = (string) enumeration.nextelement();                 if (key.startswith(key_prefix)) {                     keys.add(key);                 }             }     }             }      public boolean iskeypresent(string keyname) {         return keys.contains(keyname);     }      public string[] getkeysarray() {         string[] strtypeparam = new string[0];          return keys.toarray(strtypeparam);     } } 

class specialpropertykeysstore filters , collects special keys instance.

and can array of these keys, or check whether key present or not.

if run code, get:

[key_c, key_b, key_a] 

it string representation of returned array special key names.

change code want meet requirements.