How to get multiple values using System.getProperty

[Tariq Ahsan]

Hello,

I am using an Unix environment which has the old JDK 1.3. I am trying to use System.getProperty to read a configuration file where I want to fetch all values that partially matches with a certain key. For example the config file would have -

key.type.1=value1
some.type.1=value2
key.type.2=value3

I want to get both the values of 'key.type.1' and 'key.type.2' where the call of the getProperty method is like -

Properties pProperties = new Properties();
pProperties.getProperty("key.type");

What would be the best way to get a List of the above two key values?

Thanks

Tariq

[Stevi Deter]

Tariq,

Have you checked out the Java Tutorial on Properties?

One possible approach is to use Properties#propertyNames to get an Enumeration of the property names available, find the ones that meet your criteria, and get those properties.
[ April 24, 2008: Message edited by: Stevi Deter ]

[Rob Spoor]

Alternatively, loop until no value is found:

int index = 1;
String name = "key.type." + index;
String value = properties.getProperty(name);
while (value != null)
{
    // do something with name, index and value
    index++;
    name = "key.type." + index;
    value = properties.getProperty(name);
}

[Tariq Ahsan]

Thanks for your suggestions.
Actually I should have the example key value as -

key.type.ABC=value1 instead of key.type.1=value1

[Rob Spoor]

Then looping through the property names is the best option, using String.startsWith to check for matches.

[Irina Goble]

Tariq, you can load property names in a sorted set and then use the subSet() method to get just the ones you need. Here is an example:

import java.util.*;
public class TestProps {
    public static void main(String[] args) {
        final String prefix = args[0];
        char[] chArr = prefix.toCharArray();
        chArr[chArr.length - 1]++;
        String endPrefix = new String(chArr);
 
        Set allNames = 
            System.getProperties().stringPropertyNames();
 
        SortedSet names = 
            new TreeSet(allNames).subSet(prefix, endPrefix);
 
        System.out.println("Size: " + names.size());
 
        Iterator it = names.iterator();
        while (it.hasNext()) 
            System.out.println(it.next());
 
    }
}

Edit: Oops, missed the Java version, changed the example for 1.3.

[ April 27, 2008: Message edited by: Irina Goble ]
[ April 27, 2008: Message edited by: Irina Goble ]