Android: Cannot show more than one image

[Madhu Nandan]

Hello,

I have the following main class and thread-TCP Client. The client runs in a loop, receives messages and passes it to main class. In the main class, I parse the message and try to show different images based on the name and value of the message received. Ex: shiftDirection1 name: shiftDirection & value: 1

But I can show only the image corresponding to the first received message and the images corresponding to the remaining received messages cannot be displayed.

Please go through the code below and kindly suggest the mistake/problem and alternative ways.

Thank you for your time and efforts.

Madhu

main class:

public class TCPListen extends Activity implements TCPListener {
	private TextView mTitle;
	public String recData[] = new String[2];
	String PresentGear = "0";	
	
    /** Called when the activity is first created. */
	 @Override  
	     public void onCreate(Bundle savedInstanceState) {  
	         super.onCreate(savedInstanceState);  	         
	         
	         TcpServiceHandler handler = new TcpServiceHandler(this,this);  
	         Thread th = new Thread(handler);  
	         th.start(); 	         
	     }	     
	    
	     public String[] callCompleted(String source){ 
	        	//Log.d("TCP", "Std parser " + source);
	        	//mTitle.setText(source);
		        //String data[] = new String[2]; 
	        	
	        	//if (source.matches("<MSG><N>.*</N><V>.*</V></MSG>"))	{        	
		            Document doc = null;  
		            try{
		        	   DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
		               DocumentBuilder db = dbf.newDocumentBuilder();  
		               doc = (Document) db.parse(new ByteArrayInputStream(source.getBytes()));  
		               NodeList n = doc.getElementsByTagName("N");  
		               Node nd = n.item(0);  
		               String msgName = nd.getFirstChild().getNodeValue();  
		               NodeList n1 = doc.getElementsByTagName("V");  
		               Node nd1 = n1.item(0);  
		               String tmpVal = nd1.getFirstChild().getNodeValue();  
		               recData[0] = msgName;  
		               recData[1] = tmpVal;
		               if (recData[0].equals("currGear"))	PresentGear = recData[1];
		               Log.d("TCP", "Inside Std parser " + recData[0] + " " + recData[1]);
		               actionOnData(recData[0], recData[1]);
		              }  
		            catch(Exception e){  
		            e.printStackTrace();  
		        }		            
		        Log.d("TCP", "Just outside Std parser " + recData[0] + " " + recData[1]);
		        return recData;
	        	//} else Log.d("TCP", "Message in wrong format " + source);
	        	//mTitle.setText("Message in wrong format " + source);
	        	//return data;
		    }
	     
	     
	   //Function to display driver messages/images based on individual messages
	     public void actionOnData(String name, String value) {
	      	String tempName = name;
	      	String tempVal = value; 
	      	setContentView(R.layout.image);
	      	ImageView showImage = (ImageView) findViewById(R.id.imageView1);
	      	//Log.d("TCP", "------------>" + tempName + "  " + tempVal);	      	
	      	
	      	if (tempName.equals("shiftDirection") && tempVal.equals("1")) {
	         	//setContentView(R.layout.image);
	         	//TextView text_top = (TextView) findViewById(R.id.textView1);
	         	//showImage = (ImageView) findViewById(R.id.imageView1);        	
	         	//text_bottom.setText(Info[1]);
	         	showImage.setImageResource(R.drawable.shift_up);
	         	Log.d("TCP", "1------------>" + showImage);
	         } else if (tempName.equals("shiftDirection") && tempVal.equals("-1")) {	        	 
	         	//setContentView(R.layout.image);
	         	//TextView text_bottom = (TextView) findViewById(R.id.textView2);
	         	//Resources res = getResources();
	         	//Drawable drawable = res.getDrawable(R.drawable.shift_down);
	         	
	         	//showImage = (ImageView) findViewById(R.id.imageView1);        	
	         	//text_bottom.setText(Info[1]);
	         	showImage.setImageResource(R.drawable.shift_down);	         	
	         } else if (tempName.equals("recomGear") && tempVal != null) {
	        	 Log.d("TCP", "3------------>" + tempName + "  " + tempVal);
	         	Integer msgValue = Integer.parseInt(recData[1]);
	         	//Integer CurrentGear = (msgValue) - 1;
	         	//Log.d("TCP","in DA Images. Current gear: " + CurrentGear);
	         	//String Gear = Integer.toString(CurrentGear);
	         	setContentView(R.layout.image);
	         	TextView text_top = (TextView) findViewById(R.id.textView1);
	         	TextView text_bottom = (TextView) findViewById(R.id.textView2);
	         	showImage = (ImageView) findViewById(R.id.imageView1);        	
	         	showImage.setImageResource(R.drawable.shift_up);
	         	text_bottom.setText(PresentGear);
	         	text_top.setText(tempVal);
	         } else if (tempName.equals("currGear") && tempVal != null) {
	        	 Log.d("TCP", "4------------>" + tempName + "  " + tempVal);
	         	PresentGear = tempVal;        	
	         	//Log.d("TCP","in DA Images. Present gear1: " + PresentGear);
	         	setContentView(R.layout.image);
	         	TextView text_bottom = (TextView) findViewById(R.id.textView2);
	         	text_bottom.setText(PresentGear);        	        	
	         } else if (tempName.equals("shiftDirection") && tempVal.equals("0")) {
	        	 Log.d("TCP", "5------------>" + tempName + "  " + tempVal);
	         	Log.d("TCP","in DA Images. Present gear: " + PresentGear);
	         	setContentView(R.layout.image);
	         	TextView text_bottom = (TextView) findViewById(R.id.textView2);
	         	//TextView text_top = (TextView) findViewById(R.id.textView1);
	         	//text_top.setText("Go on");  
	         	text_bottom.setText(PresentGear);       	
	         }	      	
	      }
}

Only the image corresponding to the first if case is displayed. The program control enters the second if loop but does not show the image there.

Interface:

public interface TCPListener {
	public String[] callCompleted(String msg);
}

Thread (TCP Client):

public class TcpServiceHandler implements Runnable {  
     TCPListener _listener;            
     private Activity _act; 
     public BufferedReader in;
     public TcpServiceHandler(TCPListener listener, Activity act){    
         _listener = listener;  
         _act = act;  
     }        
   
     public synchronized void run() {  
         // TODO Auto-generated method stub           
         //if(socket==null){    
             try {  
                 //InetAddress serverAddr = InetAddress.getByName("192.168.178.25");  
                 Socket socket = new Socket("192.168.62.23", 1200, true);  
         //  
                 //while(true){  
                  try {                           
                         in = new BufferedReader(new InputStreamReader(socket.getInputStream()));  
                         final int delay = 100;
            	    	 final Timer _timer = new Timer();
            	    	 _timer.scheduleAtFixedRate(new TimerTask()	{	            		
     	            	    public void run(){
     	            	    	String str;
								try {
									str = in.readLine();
									_listener.callCompleted(str);
								} catch (IOException e) {
									// TODO Auto-generated catch block
									e.printStackTrace();
								}
     	            	    	
     	            	    }
            	    	 }, 0, delay); 
                         //final String str = in.readLine();  
                         //this._act.runOnUiThread(new Runnable(){  
   
                         //public void run() {  
                        //	 _listener.callCompleted(str);  
                           //  }                                
                         //});                                                  
                  }  
                  catch(Exception e){  
                      e.printStackTrace();  
                  }  
                 //}  
             } catch (UnknownHostException e) {  
                 // TODO Auto-generated catch block  
                 e.printStackTrace();  
             } catch (IOException e) {  
                 // TODO Auto-generated catch block  
                 e.printStackTrace();  
             }  
     }    
 }

[Daniel Trebbien]

Does actionOnData ever get called a second time?

[Madhu Nandan]

Daniel Trebbien wrote:Does actionOnData ever get called a second time?

Of course... Every time there is a new message read in the client (thread), it is passed to the parser and after parsing, the actionOnData is called from the parser.

[Daniel Trebbien]

I think that the problem is that the calls to actionOnData are not executing on the UI Thread.

Bear with me...

One thing that you can do to make the programming cleaner is to switch to using a pull parser to parse the messages that are generated by the service running at 192.168.62.23:1200.

Currently you expect data from the service to be:

<MSG><N>shiftDirection</N><V>1</V></MSG>\n <MSG><N>currGear</N><V>blah</V></MSG>\n <MSG><N>shiftDirection</N><V>-1</V></MSG>\n <MSG><N>shiftDirection</N><V>0</V></MSG>\n ...

This is rather brittle. What if your service responded with a true XML document:

<?xml version="1.0" encoding="UTF-8" ?> <MESSAGES> <MSG><N>shiftDirection</N><V>1</V></MSG> <MSG><N>currGear</N><V>blah</V></MSG> <MSG><N>shiftDirection</N><V>-1</V></MSG> <MSG><N>shiftDirection</N><V>0</V></MSG> <!-- ... --> </MESSAGES>

You can parse this with a streaming XML parser:

public class TcpMessageParser implements Runnable {
	private static final String TAG = TcpServiceHandler.class.getSimpleName();
	private TcpHandler handler;
	private TcpListener listener;
	
	public TcpMessageParser(TcpHandler handler, TcpListener listener) {
		this.handler = handler;
		this.listener = listener;
	}
	
	private void parseMessage(XmlPullParser parser) {
		String msgName = null;
		String tmpVal = null;
		
		int event;
		int currentItemDepth = parser.getDepth();
		while (((event = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > currentItemDepth) &&
			event != XmlPullParser.END_DOCUMENT) {
			if (parser.getDepth() == currentItemDepth + 1) {
				String name = parser.getName();
				if ("N".equals(name))
					msgName = parser.nextText();
				else if ("V".equals(name))
					tmpVal = parser.nextText();
			}
		}
		
		if (event == XmlPullParser.END_TAG) {
			if ("MSG".equals(parser.getName())) {
				Message msg = handler.obtainMessage(TcpHandler.MESSAGE_RUN_CALLBACK);
				msg.obj = new TcpHandler.CallbackArgs(listener, msgName, tmpVal);
				msg.sendToTarget();
			}
		}
	}

	public void run() {
		try {
			Socket socket = new Socket("192.168.62.23", 1200, true);
			InputStream is = new BufferedInputStream(socket.getInputStream());
			
			XmlPullParser parser = Xml.newPullParser();
			parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
			parser.setInput(is, null);
			
			int event;
			while (XmlPullParser.END_DOCUMENT != (event = parser.next())) {
				if ("MSG".equals(parser.getName())) {
					parseMessage(parser);
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

Now, the TcpHandler class is implemented as follows:

public class TcpHandler extends Handler {
	public static final int MESSAGE_RUN_CALLBACK = 4;
	
	public static class CallbackArgs {
		public TcpListener listener;
		public String msgName;
		public String tmpVal;
		
		public CallbackArgs(TcpListener listener, String msgName, String tmpVal) {
			this.listener = listener;
			this.msgName = msgName;
			this.tmpVal = tmpVal;
		}
	}
	
	public void handleMessage(Message msg) {
		if (msg.what == MESSAGE_RUN_CALLBACK) {
			CallbackArgs args = (CallbackArgs) msg.obj;
			args.listener.actionOnData(args.msgName, args.tmpVal);
		}
	}
}

And TcpListener is:

public interface TcpListener {
	public void actionOnData(String name, String value);
}

Your TcpListen activity becomes:

public class TCPListen extends Activity implements TcpListener {
	private TcpHandler tcpHandler;
	private TcpMessageParserThread tcpMessageParserThread;
	
	//...
	
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		tcpHandler = new TcpHandler(); // create the `TcpHandler` on the UI thread
		tcpMessageParserThread = new Thread(new TcpMessageParser(tcpHandler, this));
		tcpMessageParserThread.start();
		
		//...
	}

Then get rid of the callCompleted method.

All of the above is an extremely rough sketch of the idea, and it probably does not compile as I wrote it quickly outside of an IDE. But, it should give you enough details to get started.

Try implementing this approach and posting the result.