CODEWITHSUNDEEP
java
m0nster
m0nster

Reputation: 35

Java - Getting values from Property File

-- Scenario 1 --

This is my property file:

template.lo=rule A | template B
template.lo=rule B | template X
template.lo=rule C | template M
template.lo=rule D | template G

I dont think the above design is allowed since there's duplicate keys

-- Scenario 2 --

template.lo1=rule A | template B
template.lo2=rule B | template X
template.lo3=rule C | template M
template.lo4=rule D | template G

The above design is definitely allowed.

I want to retrieve values from Java, so I'll pass in the key to get the value. Normally, I'll use this way:

PropertyManager.getValue("template.lo1",null);

The problem is the key will keep on increasing, the above example got 4... in the future there might be 5 or 10.

So, my question is, how am I going to retrieve all the values?

If i know that there are 10 keys in total, I can use this way:

List <String> valueList = new ArrayList<String>();
     for(int i = 1; i<totalNumberOfKeys+1; i++{
     String value = (String) PropertyManager.getValue("template.lo"+i,null)
     valueList.add(value);
}

but the problem is I dont have any idea on the number of keys. I cannot pull all the values since there will be other keys which i dont want.

Any idea on this?

Upvotes: 0

Views: 303

Answers (3)

Dan Temple
Dan Temple

Reputation: 2764

ResourceBundle is what I've used previously for properties files.

If you check out the API you should be able to find how to create a ResourceBundle for you file. Then there is a containsKey(String) method that you could use as your loop condition.

So you would use something like the following:

ResourceBundle bundle = new ResourceBundle();
bundle.getBundle("My/File/Name");

List <String> valueList = new ArrayList<String>();

int i = 1;
String propertyKey = "template.lo" + i;
while( bundle.containsKey(propertyKey) ) {
    valueList.add((String) bundle.getObject(propertyKey));
    i++;
    propertyKey = "template.lo" + i;
}

Upvotes: 0

rzymek
rzymek

Reputation: 9301

I'd try to get the properties until I got null:

public List<String> getPropertyValues(String prefix) {
    List<String> values = new ArrayList<>();
    for(int i=1;;i++) {
        String value = (String) PropertyManager.getValue(prefix + i, null);
        if(value == null){
            break;
        }
        values.add(value);          
    }
    return values;
}

This assumes there are no holes in the property list (like: template.lo1=.., template.lo3=...)

Upvotes: 0

user1907906
user1907906

Reputation:

jav.util.Properties has propertyNames():

Returns an enumeration of all the keys in this property list, including distinct keys in the default property list if a key of the same name has not already been found from the main properties list.

You can loop over them and take only those you need.

There is also stringPropertyNames().

Upvotes: 3

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