Can't edit/update xml file

Question

i'm developing an android application and I want to read and edit an xml file stored in the internal storage of the device (the file is transferred to the device via usb to a specific folder, not created by the application ) .I use the DOMxmlParser of Java for this purpose, but i encounter a problem when I want to save back the updated version of the xml file. I have tested my editing function in my PC (as a simple Java Application) and it works perfect, however when i use the exact same code in the android app but no changes happen to the xml file and i get no errors.I also want to make clear that the file IS accessible since i can print its data from inside the app. Please help

Here is some Code:

Manifest

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.tsiskos.training1" >

<uses-sdk android:minSdkVersion="11" />

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />


<uses-permission
    android:name="android.permission.WRITE_EXTERNAL_STORAGE"
    android:maxSdkVersion="18" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/Theme.AppCompat.Light.DarkActionBar" >
    <activity
        android:name=".MyActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".DisplayMessageActivity"
        android:label="@string/app_name"
        android:parentActivityName=".MyActivity" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.tsiskos.training1.MyActivity" />
    </activity>
    <activity
        android:name=".EditContact"
        android:label="@string/title_activity_edit_contact" >
    </activity>
</application>

XML Editing Function

  public void editContact(String number,String oldName,String oldLimit,String newName,String newLimit) {

    try {
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = builderFactory.newDocumentBuilder();
        Document xmlDocument = builder.parse(new File(xmlPath));


        NodeList numbers = xmlDocument.getElementsByTagName("number");
        for (int i = 0; i < numbers.getLength(); i++) {
            if (((Element) numbers.item(i)).getAttribute("id").equals(number)) {

                Element currNumber = (Element) numbers.item(i);
                NodeList childs = currNumber.getChildNodes();
                for (int j = 0; j < childs.getLength(); j++) {
                    Node currElement = childs.item(j);
                    if (currElement.getNodeName().equals("contact")) {
                        NodeList currContact = currElement.getChildNodes();
                        for (int k = 0; k < currContact.getLength(); k++) {
                            Node currContactChild = currContact.item(k);
                            String currNode = currContactChild.getNodeName();
                            String currValue = currContactChild.getTextContent();
                            if (currNode.equals("name") && currValue.equals(oldName)) {

                                currContactChild.setTextContent(newName);
                            }
                            if (currNode.equals("limit") && currValue.equals(oldLimit)) {

                                currContactChild.setTextContent(newLimit);
                            }

                        }
                    }
                }
            }

        }


        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        DOMSource source = new DOMSource(xmlDocument);
        StreamResult result = new StreamResult(new File(xmlPath));



        transformer.transform(source, result);

        return xmlDocument;
    } catch (ParserConfigurationException e) {
        e.printStackTrace();
    } catch (SAXException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (TransformerConfigurationException e) {
        e.printStackTrace();
    } catch (TransformerException e) {
        e.printStackTrace();
    }

}

What i know for sure is that the reading and parsing of the file is successful. Do i miss something important related to the Android Filing System? Thanks in advance.

Not sure why the StreamResult class is failing to write to the file, but have you tried writing the results to a String, and then outputting the String to the file. As long as you have the correct permissions set, which you have, standard Java File I/O operations can be used in Android. — Sanj, Apr 09 '15 at 14:33
are you sure your device SDK is lower than 18 ? because you have included this `android:maxSdkVersion="18"` into `android:name="android.permission.WRITE_EXTERNAL_STORAGE" ` permission — Mickey Tin, Apr 09 '15 at 14:58

score 1 · Accepted Answer · edited May 23 '17 at 11:50

Apparently the problem was with the manifest file. I tried to write the results to a string and then to a file as commented by Sanj (ty for the debug tip :P) and i got the permission denied error which i could not see earlier. Although i had included the write-external-permission, i found an answer to this post suggesting a different position of the use-permission tag.

So what did the trick was moving the

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

right before the end of the manifest file.

Can't edit/update xml file

1 Answers1