Loading multiple properties files

Question

Is it possible to stack loaded properties in Java? For instance can I do:

Properties properties = new Properties();

properties.load(new FileInputStream("file1.properties"));
properties.load(new FileInputStream("file2.properties"));

and access properties from both?

Answer 1

You can do this:

Properties properties = new Properties();  properties.load(new FileInputStream("file1.properties"));  Properties properties2 = new Properties(); properties2.load(new FileInputStream("file2.properties"));  properties.putAll(properties2); 

NOTE : All the keys maintained are unique. So, the later properties loaded with same key will be overridden. Just to keep for your ref :)

Answer 2

Yes the properties stack. Properties extends Hashtable and load() simply calls put() on each key-value pair.

Relevant code from the Source:

String key = loadConvert(lr.lineBuf, 0, keyLen, convtBuf); 
String value = loadConvert(lr.lineBuf, valueStart, limit - valueStart, convtBuf); 
put(key, value); 

In other words, loading from a file doesn't clear the current entries. However, note that if the two files contain entries with the same key, the first one will be overwritten.

Answer 3

Actually, yes. You can do this. If any of the properties overlap, the newer loaded property will take place of the older one.