How to set message when I get Exception

Question

public class XMLParser {

    // constructor
    public XMLParser() {

    }


    public String getXmlFromUrl(String url) {
        String responseBody = null;

        getset d1 = new getset();
        String d = d1.getData(); // text
        String y = d1.getYear(); // year
        String c = d1.getCircular();
        String p = d1.getPage();

        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("YearID", y));

        nameValuePairs.add(new BasicNameValuePair("CircularNo", c));

        nameValuePairs.add(new BasicNameValuePair("SearchText", d));
        nameValuePairs.add(new BasicNameValuePair("pagenumber", p));
        try {

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(url);
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);

            HttpEntity entity = response.getEntity();

            responseBody = EntityUtils.toString(entity);

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return responseBody;
    }


    public Document getDomElement(String xml) {
        Document doc = null;
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {

            DocumentBuilder db = dbf.newDocumentBuilder();

            InputSource is = new InputSource();
            is.setCharacterStream(new StringReader(xml));
            doc = db.parse(is);

        } catch (ParserConfigurationException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (SAXException e) {
            Log.e("Error: ", e.getMessage());

            // i m getting Exception here

            return null;
        } catch (IOException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        }

        return doc;
    }

    /**
     * Getting node value
     * 
     * @param elem
     *            element
     */
    public final String getElementValue(Node elem) {
        Node child;
        if (elem != null) {
            if (elem.hasChildNodes()) {
                for (child = elem.getFirstChild(); child != null; child = child
                        .getNextSibling()) {
                    if (child.getNodeType() == Node.TEXT_NODE) {
                        return child.getNodeValue();
                    }
                }
            }
        }
        return "";
    }

    /**
     * Getting node value
     * 
     * @param Element
     *            node
     * @param key
     *            string
     * */
    public String getValue(Element item, String str) {
        NodeList n = item.getElementsByTagName(str);
        return this.getElementValue(n.item(0));
    }
}

I am getting Exception in this class for parsing data. I want print this message in another class which extends from Activity. Can you please tell me how? I tried much but not able to do..

public class AndroidXMLParsingActivity extends Activity {

    public int currentPage = 1;
    public ListView lisView1;
    static final String KEY_ITEM = "docdetails";
    static final String KEY_NAME = "heading";
    public Button btnNext;
    public Button btnPre;
    public static String url = "http://dev.taxmann.com/TaxmannService/TaxmannService.asmx/GetNotificationList";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // listView1
        lisView1 = (ListView) findViewById(R.id.listView1);

        // Next
        btnNext = (Button) findViewById(R.id.btnNext);
        // Perform action on click
        btnNext.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                currentPage = currentPage + 1;
                ShowData();
            }
        });

        // Previous
        btnPre = (Button) findViewById(R.id.btnPre);
        // Perform action on click
        btnPre.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                currentPage = currentPage - 1;
                ShowData();
            }
        });

        ShowData();
    }

    public void ShowData() {
        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(url); // getting XML

        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_ITEM);

        int displayPerPage = 5; // Per Page
        int TotalRows = nl.getLength();
        int indexRowStart = ((displayPerPage * currentPage) - displayPerPage);
        int TotalPage = 0;
        if (TotalRows <= displayPerPage) {
            TotalPage = 1;
        } else if ((TotalRows % displayPerPage) == 0) {
            TotalPage = (TotalRows / displayPerPage);
        } else {
            TotalPage = (TotalRows / displayPerPage) + 1; // 7
            TotalPage = (int) TotalPage; // 7
        }
        int indexRowEnd = displayPerPage * currentPage; // 5
        if (indexRowEnd > TotalRows) {
            indexRowEnd = TotalRows;
        }

        // Disabled Button Next
        if (currentPage >= TotalPage) {
            btnNext.setEnabled(false);
        } else {
            btnNext.setEnabled(true);
        }

        // Disabled Button Previos
        if (currentPage <= 1) {
            btnPre.setEnabled(false);
        } else {
            btnPre.setEnabled(true);
        }

        // Load Data from Index
        int RowID = 1;
        ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();
        HashMap<String, String> map;

        // RowID
        if (currentPage > 1) {
            RowID = (displayPerPage * (currentPage - 1)) + 1;
        }

        for (int i = indexRowStart; i < indexRowEnd; i++) {
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key => value
            map = new HashMap<String, String>();
            map.put("RowID", String.valueOf(RowID));
            map.put(KEY_NAME, parser.getValue(e, KEY_NAME));

            // adding HashList to ArrayList
            menuItems.add(map);

            RowID = RowID + 1;

        }

        SimpleAdapter sAdap;
        sAdap = new SimpleAdapter(AndroidXMLParsingActivity.this, menuItems,
                R.layout.list_item, new String[] { "RowID", KEY_NAME },
                new int[] { R.id.ColRowID, R.id.ColName });
        lisView1.setAdapter(sAdap);
    }

}

This my class where I want to Print that message

Answer 1

I would say, add throws SAXException in XMLParser.getDomElement() method and don't catch SAXException in this method as:

  public Document getDomElement(String xml) throws SAXException {

Catch the SAXException in AndroidXMLParsingActivity.ShowData() where you are calling getDomElement() method and print the message in the desired way e.g.

 public void ShowData() {
    XMLParser parser = new XMLParser();
    String xml = parser.getXmlFromUrl(url); // getting XML

    Document doc = null;
    try{
          doc  = parser.getDomElement(xml); // getting DOM element
      }catch(SAXException sae){
         //print the desired message here
      }

      .......
      .......
 }

Answer 2

Simply pass the constructor to your XMLParser class and used that there as your constructor. Or, you can try with use of getApplicationContext() You can simply show the Toast when you getting an exception like below -

try {

    DocumentBuilder db = dbf.newDocumentBuilder();
    InputSource is = new InputSource();
    is.setCharacterStream(new StringReader(xml));
    doc = db.parse(is);

} catch (ParserConfigurationException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(con, e.toString(), Toast.Long).show();   // Will show the message of exception
    return null;
} catch (SAXException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(con, e.toString(), Toast.Long).show();   // Will show the message of exception
    // i m getting Exception here
    return null;
} catch (IOException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(con, e.toString(), Toast.Long).show();   // Will show the message of exception
    return null;
}

Update

Okay, just pass the constructor as per below - Where you are calling that XMLparser class just call like below -

....
XMLParser xml = new XMLParser(AndroidXMLParsingActivity.this);
....

And, in XMLParser class there mention your constructor like below -

public class XMLParser {

    Context con;

    public XMLParser(Context context) {

        con = context;

    }
......
}

And, use this con as your constructor in your XMLParser class.

Answer 3

You can simply surround your code with a Try/Catch block like this:

String xml;
Document doc;
NodeList nl;

try {

    xml = parser.getXmlFromUrl(url); // getting XML
    doc = parser.getDomElement(xml); // getting DOM element
    nl = doc.getElementsByTagName(KEY_ITEM);
} catch (Exception e) {
    Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}

This way you don't have to make any changes in your XMLParser class and you can easily handle any exceptions occurring while parsing your code in the main class itself. Also, for displaying error messages, Toast is the best thing according to me.

Hope this helps.. Thanks.

Answer 4

For showing Message from Non Activity Class you will need to pass Current Activity Context as:

public class XMLParser {

Context context
    // constructor
    public XMLParser(Context conts) {
    context =conts;
    }
///YOUR CODE
try {

    DocumentBuilder db = dbf.newDocumentBuilder();
    InputSource is = new InputSource();
    is.setCharacterStream(new StringReader(xml));
    doc = db.parse(is);

} catch (ParserConfigurationException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(context, e.toString(), Toast.Long).show();   
    return null;
} catch (SAXException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(context, e.toString(), Toast.Long).show();  
    // i m getting Exception here
    return null;
} catch (IOException e) {
    Log.e("Error: ", e.getMessage());
    Toast.makeToast(context, e.toString(), Toast.Long).show();  
    return null;
}