How do parse xml in android using SAX Parser?

Question

I'm a noob to android and I'm trying to learn how to parse xml with the SAX parser. I've written a test application to try to implement it, but i can't seem to make it work. I want my textview to display corresponding values from an xml but it's not working. Can anyone help?

Parser

public class ParseTestActivity extends Activity implements View.OnClickListener {
/** Called when the activity is first created. */
final static String TAG = "spotxml";
TextView tv;
WebView xml;
Button help, help2;
int livespot = 0;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    tv = (TextView) findViewById(R.id.textView1parsed);
    help = (Button) findViewById(R.id.button1);
    help2 = (Button) findViewById(R.id.button2);
    help.setOnClickListener(this);
    help2.setOnClickListener(this);
    xml = (WebView) findViewById(R.id.webView1);

    try{
    xml.loadUrl("http://www.xmlcharts.com/cache/precious-metals.xml");
    }catch (Exception e){
        e.printStackTrace();
    }


    try{
        URL xmlcharts = new URL("http://www.xmlcharts.com/cache/precious-metals.xml");  
        //InputSource local = new InputSource(getResources().openRawResource(R.raw.preciousmetals));
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        XMLReader xr = sp.getXMLReader();
        HandlingXMLStuff doingWork = new HandlingXMLStuff();
        xr.setContentHandler(doingWork);
        xr.parse(new InputSource(xmlcharts.openStream()));  
        //xr.parse(local);
        XMLDataCollected information = doingWork.getInformation(); 
        //String information = doingWork.getInformation();
        tv.setText(information.toString());
        livespot = Integer.parseInt(information.toString());
    }catch(Exception e){
        Toast.makeText(ParseTestActivity.this, "Error", Toast.LENGTH_LONG).show();
        Log.e(TAG, "WeatherQueryError", e);
    }




}


@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    switch(v.getId()){
    case R.id.button1:
        try{
            URL xmlcharts = new URL("http://www.xmlcharts.com/cache/precious-metals.xml");  
            //InputSource local = new InputSource(getResources().openRawResource(R.raw.preciousmetals));
            SAXParserFactory spf = SAXParserFactory.newInstance();
            SAXParser sp = spf.newSAXParser();
            XMLReader xr = sp.getXMLReader();
            HandlingXMLStuff doingWork = new HandlingXMLStuff();
            xr.setContentHandler(doingWork);
            xr.parse(new InputSource(xmlcharts.openStream()));  
            //xr.parse(local);
            XMLDataCollected information = doingWork.getInformation();
            //String information = doingWork.getInformation();
            tv.setText(information.toString());
            livespot = Integer.parseInt(information.toString());
        }catch(Exception e){
            Toast.makeText(ParseTestActivity.this, "Error", Toast.LENGTH_LONG).show();
            Log.e(TAG, "WeatherQueryError", e);
        }
        break;
    case R.id.button2:
        try{                
            //URL xmlcharts = new URL("http://www.xmlcharts.com/cache/precious-metals.xml");    
            InputSource local = new InputSource(getResources().openRawResource(R.raw.preciousmetals));
            SAXParserFactory spf = SAXParserFactory.newInstance();
            SAXParser sp = spf.newSAXParser();
            XMLReader xr = sp.getXMLReader();
            HandlingXMLStuff doingWork = new HandlingXMLStuff();
            xr.setContentHandler(doingWork);
            //xr.parse(new InputSource(xmlcharts.openStream()));    
            xr.parse(local);
            XMLDataCollected information = doingWork.getInformation();
            //String information = doingWork.getInformation();
            tv.setText(information.toString());
            livespot = Integer.parseInt(information.toString());
        }catch(Exception e){
            Toast.makeText(ParseTestActivity.this, "Error", Toast.LENGTH_LONG).show();
            Log.e(TAG, "WeatherQueryError", e);
        }
        break;
}
}}

Content Handler

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;



public class HandlingXMLStuff extends DefaultHandler {

        private boolean in_prices = false;
        private boolean in_pricelist = false;
        private boolean in_uspricegold = false;
        private boolean in_uspricesilver = false;
        String gs = null;
        String ss = null;


    private XMLDataCollected info = new XMLDataCollected();

    //public String getInformation(){
    //  return info.datatoString();
    //}
    public XMLDataCollected getInformation(){
        return this.info;
    }



    @Override
    public void startDocument() throws SAXException {
    this.info = new XMLDataCollected();
    }

    @Override
    public void endDocument() throws SAXException {
              // Nothing to do
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // TODO Auto-generated method stub
        if (localName.equalsIgnoreCase("prices")) {
            this.in_prices = true ;
        }else if (localName.equalsIgnoreCase("pricelist")) {
            String attrValue = attributes.getValue("currency");
            if (attrValue.equalsIgnoreCase("usd")){
            this.in_pricelist = true;
        }else if (localName.equalsIgnoreCase("price")){
            String attrValue2 = attributes.getValue("commodity");
            if (attrValue2.equalsIgnoreCase("gold")){
            this.in_uspricegold = true;
        }else if (localName.equalsIgnoreCase("price")){
            String attrValue3 = attributes.getValue("commodity");
            if (attrValue3.equalsIgnoreCase("silver")){
            this.in_uspricesilver = true;
        }
        }}}
    }
     @Override
      public void endElement(String namespaceURI, String localName, String qName)
                    throws SAXException {
             if (localName.equalsIgnoreCase("prices")) {
                 this.in_prices = false;
             }else if (localName.equalsIgnoreCase("pricelist")) {
                 this.in_pricelist = false;
             }else if (localName.equalsIgnoreCase("price")) {
                 this.in_uspricegold = false;
             }else if (localName.equalsIgnoreCase("price")) {
                 this.in_uspricesilver = false;       
             }
     }  

     @Override
     public void characters(char[] ch, int start, int length)throws SAXException {

                    if(this.in_uspricegold) {                       
                    //info.setSpotGold(new String (ch, start, length));                     
                    //} 
                    int spotgold = Integer.parseInt(new String (ch, start, length));                        
                    info.setSpotGold(spotgold);
                    this.in_uspricegold = false;
                    }else{}

                    if(this.in_uspricesilver){                     
                    //info.setSpotSilver(new String(ch, start, length));                      
                    // }    
                    int spotsilver = Integer.parseInt(new String(ch, start, length));                       
                    info.setSpotSilver(spotsilver);
                    this.in_uspricesilver = false;
                    }else{}
            }

    }

Collected Data Set

public class XMLDataCollected{

 private int spotsilver = 0;
 private int spotgold = 0;

    public int getSpotGold() {
    return spotgold;
    }   
    public void setSpotGold(int spotgold){          
    this.spotgold = spotgold;   
    }

    public int getSpotSilver() {
    return spotsilver;
    }           
    public void setSpotSilver(int spotsilver){      
    this.spotsilver = spotsilver;
    }

    public String toString(){
        return  "gold " + spotgold + " silver "+ spotsilver;

    }

}

Please, if you found the answer useful you should accept it. Otherwise just tell us what is still not working and we'll see how to fix it! :) — Enrichman, Jul 10 '12 at 09:16

Enrichman · Accepted Answer · 2012-07-19T00:04:39.260

First of all your method characters has to be much simpler. The only thing that it does is to read the characters between the tags. It will be like this:

public void characters(char[] ch, int start, int end) {
    buffer.append(new String(ch, start, end));
}

As you can see I'm using a StringBuffer as a private field. It's instantiate at the beginning of the startElement method and "resetted" at the beginning of the endElement.

    value = buffer.toString();
    buffer.setLength(0);

The field value will actually keep the real value of the field.

All my class for reference:

private String value;
private StringBuffer buffer;

@Override
public void startElement(
        String nameSpaceURI, 
        String localName, 
        String qName, 
        Attributes atts
        ) {

    buffer = new StringBuffer();

    if(localName.equals("myTag"))
    bean = new Bean();

}

public void endElement(
        String uri, 
        String localName, 
        String qName) {

    value = buffer.toString();
    buffer.setLength(0);

    if(localName.equals("myTag") {
        bean.setSomething(value);
    }

}

public void characters(char[] ch, int start, int end) {
    buffer.append(new String(ch, start, end));
}

Hope this helps. :)

EDIT

Here the code adapted to the op xml. I haven't tried it but SHOULD work. ;)

private String value;
private StringBuffer buffer;

private XMLCOllected info;
private boolean inPriceList;
private boolean inGold;
private boolean inSilver;

@Override
public void startElement(
        String nameSpaceURI,
        String localName,
        String qName,
        Attributes atts
) {

    buffer = new StringBuffer();

    if(localName.equals("prices")) {
        this.info = new XMLCollected();
    } else if(localName.equals("pricelist")) {
        String attr = atts.getValue("currency");
        if(attr.equals("usd")) {
            this.inPriceList = true;
        }
    } else if(localName.equals("price") && inPrices) {
        String attr = atts.getValue("commodity");
        if(attr.equals("gold")) {
            this.inGold = true;
        } else if(attr.equals("silver")) {
            this.inSilver = true;
        }
    }
}

public void endElement(
        String uri,
        String localName,
        String qName) {

    value = buffer.toString();
    buffer.setLength(0);

    if(localName.equals("price") && inGold && inPriceList) {
        this.info.setSpotGold(value);
        this.inGold = false;
    } else if(localName.equals("price") && inSilver && inPriceList) {
        this.info.setSpotSilver(value);
        this.inSilver = false;
    } else if(localName.equals("pricelist")) {
        this.inPriceList = false;
    }
}

public void characters(char[] ch, int start, int end) {
    buffer.append(new String(ch, start, end));
}

Thanks for responding. I'm actually a bit confused now, though. Bear with me I'm a noob. lol. in my case should i enter the line value = buffer.toString(); in the characters method above... buffer.append(new String(ch, start, end));? — B. Money, Jul 18 '12 at 19:58
No problem, I'm not that experienced! Btw, nope. That's because the characters method can be called multiple times, so it should be used just to collect the value between the tags. You should set the value in the closing tag, not in the characters method. Can you provide an example of the XML file that you're parsing (so I can use your bean to improve the answer)? — Enrichman, Jul 18 '12 at 23:08
Below is what i am attempting to parse. this is the url. (http://www.xmlcharts.com/cache/precious-metals.xml)...... 1572.58 575.00 1405.50 27.23 — B. Money, Jul 18 '12 at 23:16
IT WORKS!!! I have been trying to figure this out for two weeks. You're a genius. Thank you soooo much. — B. Money, Jul 19 '12 at 00:57
Good to hear this! I've learnt here how to make it for my app as well, so we have both to thanks stackoverflow! ;) — Enrichman, Jul 19 '12 at 00:58

How do parse xml in android using SAX Parser?

1 Answers1