Properties.store throws NullPointerException

Question

Hi,
I have a strange problem with the java.util.Properties class. Calling
store on a Properties object AFTER I've called System.setProperties
always leads to a NullPointerException.
Code sample 1:
Properties props = new Properties();
props.put("prop1", "val1");
ByteArrayOutputStream out = new ByteArrayOutputStream();
props.store(out, "Header");
Code sample 2:
Properties props = new Properties();
props.put("prop1", "val1");
System.setProperties(props);
ByteArrayOutputStream out = new ByteArrayOutputStream();
props.store(out, "Header");
Code sample 1 works fine, sample 2 throws a NullPointerException in
the last line. Even code sample 3 throws the exception in the last
line.
Code sample 3:
Properties props = new Properties();
props.put("prop1", "val1");
System.setProperties(props);
props = new Properties();
ByteArrayOutputStream out = new ByteArrayOutputStream();
props.store(out, "Header");
How can I avoid this problem. I can't guarantee that no one calls
System.setProperties before the store call, so this is no solution. I
need the store call to save the properties to a String. At a later
time I want to use Properties.load to read the properties from this
String (via ByteArrayInputStream). Perhaps there is another way to
store/load properties to/from a String?
Thanks,
Markus

Answer 1

Hi,
I think the problem is that if u create a new Property it will create a new property with null value
Creates an empty property list with no default values.
and if u try to override the systemproperty creates a null pointer Exception.
Insteda try this
Properties p=System.getProperties();
          p.put("prop1","val1");
          System.setProperties(p);
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          p.store(out, "Header");
means , try to get the property object from the system and go ahead with ur coding is working fine
Greetz
Kumar.R