Doubts in reading a '.properties' file

Question

Hi All,
I have a doubt regarding properties file from which I am reading some key-values. Now I have few different keys (4-5) having same value .e.g.
key1=value1
key2=value1
key3=value1
key4=value1
key5=value1
Now I need to read these keys from different places and I also need to update the value to say 'value2' for all the keys e.g.
key1=value2
key2=value2
key3=value2
key4=value2
key5=value2
Now, since i need to update the values of all the keys, I am thinking of having another key-value pair (e.g. key=value1) in the same property file, and using the value of this key as value for all the keys displayed above. So that when I update the value of this key ( key=value2), I dont need to update the values of all the keys, since those keys will be reading the values from this key's value.
I hope i am clear with this explanation.... ;-)
My first question is, 'IS IT POSSIBLE' ???
If yes, then how????
Thanks in advance
Inder Jeet Singh

Answer 1

The following little class is from my old bag of tricks:import java.util.Properties;
public class XProperties extends Properties {
     public static final String BEG= "${";
     public static final String END= "}";
     public XProperties() { super(); }
     public XProperties(Properties def) { super(def); }
     public String getRawProperty(String key) { return getRawProperty(key, null); }
     public String getRawProperty(String key, String def) {
          return super.getProperty(key, def);
     public String process(String val) {
          for (int i, j, n= val.length(); n >= 0 && (i= val.lastIndexOf(BEG, n)) >= 0 &&
            (j= val.indexOf(END, i)) >= 0; ) {
               String pat= val.substring(i+BEG.length(), j);
               String sub= super.getProperty(pat);
               if (sub != null) {
                    val= val.replaceAll("\\Q"+BEG+pat+END+"\\E", sub);
                    n= val.length();
               else
                    n= i-1;
          return val;
     public String getProperty(String key) { return getProperty(key, null); }
     public String getProperty(String key, String def) {
          String val= super.getProperty(key);
          return val == null?def:process(val);
}If you use an XProperties object instead of a Properties object
you can do the following in your .properties file:key= value1
key1= ${key}
key2= ${key}
key3= ${key}
key4= ${key}
key5= ${key}... if you want to change the value, all you have to do is change the
value of the 'key=value1' line.
kind regards,
Jos