CODEWITHSUNDEEP
javaproperties
ClueMinus
ClueMinus

Reputation: 393

Multiple values in java.util.Properties

It seems that java.util.Properties assumes one value per propery key. That is,

foo=1
foo=2

is not expected,

Is there a class for this kind of multi-value property sheet, which also provides the load method?

Upvotes: 39

Views: 95957

Answers (5)

Nick Holt
Nick Holt

Reputation: 34311

Try:

foo=1,2

String[] foos = properties.getProperty("foo", "").split(",");

Upvotes: 72

Clerenz
Clerenz

Reputation: 851

If you have a more complex example you might use the following:

# pairs of properties
source1=foo
target1=bar
source2=anotherFoo
target2=regardingBar
source3= ...

In your code you will have to search:

Map<String, String> myMap = new HashMap<>();
for (int i=1; i<max; i++) {
  String source = properties.get("source" + i);
  String target = properties.get("target" + i);
  if (source == null || target == null) {
    break;
  }
  myMap.put(source, target);
}

Drawback: updating the properties file. If you remove values *2, all the following values will not be added. To improve you might want to replace the break with a continue and stick to a maximum of allowed pairs.

Upvotes: 1

Pablojim
Pablojim

Reputation: 8582

This won't provide the load method but a place to store them you could use a apache commons multivaluemap:

"A MultiValueMap decorates another map, allowing it to have more than one value for a key. "

This is often a requirement for http request parameters...

http://commons.apache.org/collections/apidocs/org/apache/commons/collections/map/MultiValueMap.html

Upvotes: 0

KLE
KLE

Reputation: 24159

Correct answer by Nick.

Or, if you can give a different subname to each value, you could have your properties be:

    my.properties

    foo.title=Foo
    foo.description=This a big fat foo.

Upvotes: 4

ZZ Coder
ZZ Coder

Reputation: 75456

The java.util.Properties function is pretty limited. If you want support list, you might want try PropertyConfiguration from Apache Commons Configuration,

http://commons.apache.org/configuration/userguide/howto_properties.html#Using_PropertiesConfiguration

With it, you can set any delimiters to your list and it will split for you automatically. You can also do other fancy things in properties file. For example,

foo=item1, item2
bar=${foo}, item3
number=123

You can retrieve it like this,

Configuration config = new PropertiesConfiguration("your.properties");
String[] items = config.getStringArray("bar"); // return {"item1", "item2", "item3"}
int number = config.getInt("number", 456); // 456 is default value

Upvotes: 23

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