How to get address of a Java Object?

java string stringbuffer object-address
Iguramu picture Iguramu · Sep 1, 2009 · Viewed 50.4k times · Source

Is there a way to get address of a Java object?

Where the question comes from?: At First, I read properties file and all the data from file was placed into table. Properties file can update. So, I want to listen that file. I listen an object using PropertyChangeSupport and PropertyChangeListener. 

updatedStatus = new basit.data.MyString();
    updatedStatus.addPropertyChangeListener(new java.beans.PropertyChangeListener() {

        //After changes "i", we inform the table model about new value
            public void propertyChange(PropertyChangeEvent evt) {
                Object objec=evt.getNewValue();
                tableModel.setValueAt(objec.toString(), 0, 5);
            }
        });

If updatedStatus changes then i update table. MyString class have private String "Value". I want to listen properties file. So, it should make updatedStatus.value and String of Properties File equal at the same address. If i can do it, so i don't need to listen properties file.

updatedStatus.setValue(resourceMap.getString("HDI.Device.1.Name"));

I tried to use StringBuffer, but i couldn't achieve it. That's why, I asked the question.

Answer

Jon Skeet picture Jon Skeet · Sep 1, 2009

Firstly - no, you can't get the address of an object in Java; at least, not pure Java with no debugging agent etc. The address can move over time, for one thing. You don't need it.

Secondly, it's slightly hard to follow your explanation but you certainly won't be able to get away without listening for changes to the file itself. Once you've loaded the file into a Properties object, any later changes to the file on disk won't be visible in that object unless you specifically reload it.

Basically you should listen for changes to the file (or poll it) and reload the file (either into a new Properties or overwriting the existing one) at that point. Quite whether you also need to listen for updates on the string container will depend on your application.

Related questions

Create a string with n characters

Is there a way in java to create a string with a specified number of a specified character? In my case, I would need to create a string with 10 spaces. My current code is: StringBuffer outputBuffer = new StringBuffer(length); for (…

Read More
What is the difference between String and StringBuffer in Java?

What is the difference between String and StringBuffer in Java? Is there a maximum size for String?

Read More
What is difference between mutable and immutable String in java

As per my knowledge, a mutable string can be changed, and an immutable string cannot be changed. Here I want to change the value of String like this, String str="Good"; str=str+" Morning"; and other way is, StringBuffer str= …

Read More