如何替换XML中的空值

Question

I am adding some more tags in xml file by using DOM parser. I am creating some new tags using DOM parser and want to set their values by passing arraylist. My arraylist contains values which I am retrieving from database.

My code is a follows:

loading file using dom parser


  for(String s:a.List){
 Element n= doc.createElement("value");
n.appendChild(doc.createTextNode(String.valueOf(s)));

    }

here I am creating new tag and passing values of s in that tag.

Output I am getting:

<value>1</value>

<value>2</value>

<value>3</value>

<value>null</value>

<value>null</value>

<value>4</value>

; ; so on

Expected output:

<value>1</value>
<value>2</value>

<value>3</value>

<value/>

<value/>

<value>4<value>

I want to remove null which is coming from databse to arraylist and than to xml and get form as mentioned above Please help...

Answer 1

Empty Tags:

The String.valueOf() is forcing null to be converted to the String "null" . Just remove that conversion and the null tags will collapse:

for(String s : a.List){
    Element n = doc.createElement("value");
    n.appendChild(doc.createTextNode(s)); // null renders as empty
}

The same collapsing should happen for empty Strings "" (which might be convenient if you're doing something else with the String too):

for(String s : a.List){
    Element n = doc.createElement("value");
    if(s == null) { s = ""; } // force nulls to be empty Strings
    n.appendChild(doc.createTextNode(s));
}

...or you can conditionally omit the child (which also creates a collapsed tag):

for(String s : a.List){
    Element n = doc.createElement("value");
    if(s != null) {
        n.appendChild(doc.createTextNode(s)); // only append non-null values
    }
}

No Tags:

If you wanted to omit the tag entirely you could do this:

for(String s : a.List){
    if(s != null) {
        Element n = doc.createElement("value");
        n.appendChild(doc.createTextNode(s));
    }
}

Answer 2

Would this work for you?

String value = String.valueOf(s);
if (! 'null'.equals(value)) { n.appendChild(doc.createTextNode(value)); }

This should leave the node n empty if s is "null" .

Answer 3

I have try below code:

for(String b:a)
{
    Element valuesElements = doc.createElement("values");
    if(b!=null)
    {
        valuesElements.appendChild(doc.createTextNode(b));
    }
        rootElement.appendChild(valuesElements);
}

and get below result:

<root><values>a</values><values/></root>

Probably this is what you want