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Thread: Method calls/initialization issues

  1. #1
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    Unhappy Method calls/initialization issues

    Hi there,

    First time posting here - wondering if anyone could lend a hand!
    I'm making an import/export of xml - I have the import of xml sorted I'm just trying to finish off the export.
    My export class is called XmlWriter.java


    Inside the class I have an updateFile method to update an xml file as such:
    public void updateFile(Environment environment,Document doc)
    {
     // code
    }

    I then in my main method have
    public static void main(String argv[]){
     
                   //declare new object of class
                  XmlWriter xmlWriter = new XmlWriter();   
     
                   //test testUpdate method
                   //     xmlWriter.testUpdate();
     
                  Environment environment = ;
                  Document doc = ;
     
                   //call method to update
                  xmlWriter.updateFile(environment,doc);
     
                   //call method to export
     
     
           }

    I don't know what to make my variables equal to - eclipse keeps trying to use null but obviously that won't work. The Environment is another class that just contains getters and setters for the 3 different databases (that are in the xml file) and the getter/setter for the environment ID (also in xml file). Any help would be appreciated as I'm confused as to what to set the variables to :S


  2. #2
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    Default Re: Method calls/initialization issues

    What does the updateFile() method do? Shouldn't you already have an Environment and a Document if you're trying to do something with them? Where are they coming from? What types of constructors do they have?
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  3. #3
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    Default Re: Method calls/initialization issues

    Document doc is only used in documentBuilderFactory to get hold of a document and parse it so it can be edited/updated

    Environment is a class that uses getters/setters that refer to the 'environment' and 'Database' in the xml file

    This is my updateFile method:
    public void updateFile(Environment environment,Document doc)
    {
    //get the tag environment                
    Node env = doc.getElementsByTagName( "environment" ).item(0);
     
     
     
     
    //assign nodelist to env so it gets the child nodes of the environment
                         NodeList list = env.getChildNodes();
                          for (int i2 = 0; i2 < list.getLength();i2++)
                         {
     
                                //go onto the next node
                               Node node = list.item(i2);
     
     //get the elements from environment and then update their values
                                //using setTextContent(" ");
                                if ("URL" .equals(node.getNodeName())){
                                      node.setTextContent( "" );
                               }
    }
    Last edited by AliceH; September 17th, 2014 at 09:44 AM.

  4. #4
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    Default Re: Method calls/initialization issues

    The classes Document and Enviroment, where they written by you? Are they part of some third party library? Or were they written by your instructor / teacher / etc?

    Usually you should simply read the API or the source code of the class you want to use if you want to know which constructor to call.

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