Wednesday, October 5, 2011

Parsing Twitter JSON feed and displaying in List Field -- Blackberry


Searching for Blackberry JSON Parser ?? Here is your answer.. Here i have explained, how to parse Twitter JSON feed and display in List Field with a neat black background.



Note:
I have used "org.json.me" in this project.

CODE



public class jsonparsing extends UiApplication implements ListFieldCallback, FieldChangeListener
{

public static void main(String[] args)
{
jsonparsing app = new jsonparsing();
app.enterEventDispatcher();
}

MainScreen screen = new MainScreen();
public long mycolor ;
Font myFont1;
private static ListField _list;
private static Vector listElements = new Vector();
VerticalFieldManager hfm;
VerticalFieldManager subManager;
Connection _connectionthread;

RichTextField rt;

public jsonparsing()
{
super();
pushScreen(screen);
screen.setTitle("Blackberry Json Parser");
final Bitmap backgroundBitmap = Bitmap.getBitmapResource("blackbg.png");

hfm = new VerticalFieldManager(Manager.NO_VERTICAL_SCROLL | Manager.NO_VERTICAL_SCROLLBAR )
{

public void paint(Graphics graphics)
{
graphics.drawBitmap(0, 0, Display.getWidth(),Display.getHeight(),backgroundBitmap, 0, 0);

super.paint(graphics);
}
};

subManager = new VerticalFieldManager(Manager.VERTICAL_SCROLL | Manager.VERTICAL_SCROLLBAR )
{
protected void sublayout( int maxWidth, int maxHeight )
{
int displayWidth = Display.getWidth();
int displayHeight = Display.getHeight();

super.sublayout( displayWidth, displayHeight);
setExtent( displayWidth, displayHeight);
}
};
screen.add(hfm);

_list = new ListField()

{

public void paint(Graphics graphics)

{
graphics.setColor((int) mycolor);
super.paint(graphics);

}

};
mycolor = 0x00FFFFFF;
_list.invalidate();
_list.setEmptyString("* Feeds Not Available *", DrawStyle.HCENTER);
_list.setRowHeight(50);
_list.setCallback(this);

hfm.add(subManager);

rt = new RichTextField() {

public void paint(Graphics g) {
g.setColor(Color.WHITE);
super.paint(g);
}
};
_connectionthread = new Connection();
_connectionthread.start();
}


protected boolean navigationClick(int status, int time)
{
try
{
Field focus = UiApplication.getUiApplication().getActiveScreen().getLeafFieldWithFocus();
if(focus == _list)
{
//UiApplication.getUiApplication().pushScreen(new screen3());
}

}
catch(Exception e)
{
System.out.println("Exception:- : navigationClick() "+e.toString());
}
return true;
}

public boolean onSavePrompt()
{
return true;
}

private class Connection extends Thread
{
public Connection()
{
super();
}

public void run() {

try {

JSONArray result = new JSONArray(getJsonresponse());
int chk = result.length();
String opString[] = new String[chk];

for (int i = 0; i <17; i++)
{
opString[i] = result.getJSONObject(i).getString("text");
listElements.addElement(opString[i]);
}

}
catch (Exception e) {
System.out.println(e.toString());
rt.setText("catch1: "+e.toString());
}
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
_list.setSize(listElements.size());
subManager.add(_list);
screen.invalidate();
}
});
}

}


public String getJsonresponse()
{
HttpConnection conn = null;
InputStream in = null;
String _response = null;
int code;

try {
conn = (HttpConnection) Connector.open("http://twitter.com/status/user_timeline/clusterlessons.json", Connector.READ);
conn.setRequestMethod(HttpConnection.GET);

code = conn.getResponseCode();

if (code == HttpConnection.HTTP_OK) {
in = conn.openInputStream();
ByteArrayOutputStream out = new ByteArrayOutputStream();

byte[] buffer = new byte[in.available()];
int len = 0;

while (-1 != (len = in.read(buffer))) {
out.write(buffer);
}

out.flush();
_response = new String(out.toByteArray());

System.out.println(_response);
//rt.setText(_response);


if (out != null){
out.close();
}
if (in != null){
in.close();
}
if (conn != null){
conn.close();
}
}

} catch (Exception e) {
System.out.println("HTTP Thread: " + e.toString());
Dialog.alert(e.toString());
}

return _response;
}

public void drawListRow(ListField list, Graphics g, int index, int y, int w)
{
String tes = (String)listElements.elementAt(index);
int yPos = 0+y;
g.drawText(tes, 10, 15+y, 0, w);
g.drawLine(0, yPos, w, yPos);
}


public Object get(ListField list, int index)
{
return listElements.elementAt(index);
}
public int indexOfList(ListField list, String prefix, int string)
{
return listElements.indexOf(prefix, string);
}
public int getPreferredWidth(ListField list)
{
return Display.getWidth();
}
public void insert(String toInsert, int index) {
listElements.addElement(toInsert);
}

public void fieldChanged(Field field, int context) {


}
}



Your output will be like this.



That's it. JSON parsing done. You can download the sample project below.


Arun Kumar Munusamy Web Developer

Morbi aliquam fringilla nisl. Pellentesque eleifend condimentum tellus, vel vulputate tortor malesuada sit amet. Aliquam vel vestibulum metus. Aenean ut mi aucto.

1 comment: