Android: How to detect double-tap?
I have a problem with implementing double tap. Well I implemented the onGestureListener and I had the gestureDetector, but I'm not sure where is the problem, here is my code:
public class home extends TabActivity implements OnGestureListener {
/** Called when the activity is first created. */
private EditText queryText;
private ResultsAdapter m_adapter;
private ProgressDialog pd;
final Handler h = new Handler();
private TabHost mTabHost;
private ArrayList<SearchItem> sResultsArr = new ArrayList<SearchItem>();
private String queryStr;
private JSONObject searchResponse;
private GestureDetector gestureScanner;
final Runnable mUpdateResults = new Runnable() {
public void run() {
updateListUi();
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button search = (Button)findViewById(R.id.search);
Button testButt = (Button)findViewById(R.id.testbutt);
queryText = (EditText)findViewById(R.id.query);
ListView lvr = (ListView)findViewById(R.id.search_results);
//initialise the arrayAdapter
this.m_adapter = new ResultsAdapter(home.this, R.layout.listrow, sResultsArr);
lvr.setAdapter(this.m_adapter);
lvr.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
pd = ProgressDialog.show(home.this, null,"Loading products from server", true, false);
}
});
gestureScanner = new GestureDetector(this,this);
gestureScanner.setOnDoubleTapListener(new OnDoubleTapListener(){
public boolean onDoubleTap(MotionEvent e) {
//viewA.setText("-" + "onDoubleTap" + "-");
pd = ProgressDialog.show(home.this, null,"Loading products from server", true, false);
return false;
}
public boolean onDoubleTapEvent(MotionEvent e) {
// viewA.setText("-" + "onDoubleTapEvent" + "-");
return false;
}
public boolean onSingleTapConfirmed(MotionEvent e) {
//viewA.setText("-" + "onSingleTapConfirmed" + "-");
return false;
}
});
//initialise tab contents
mTabHost = getTabHost();
mTabHost.addTab(mTabHost.newTabSpec("tab1").setIndicator("Home").setContent(R.id.homepage));
mTabHost.addTab(mTabHost.newTabSpec("tab2").setIndicator("Search Results").setContent(R.id.tab2));
mTabHost.setCurrentTab(0);
//sets the respective listeners
testButt.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
if(mTabHost.getTabWidget().getVisibility()==View.GONE){
mTabHost.getTabWidget().setVisibility(View.VISIBLE);
}
else{
mTabHost.getTabWidget().setVisibility(View.GONE);
}
}
});
search.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
sResultsArr.clear();
queryStr = "http://rose.mosuma.com/mobile?query=" + queryText.getText().toString();
pd = ProgressDialog.show(home.this, null,"Loading products from server", true, false);
goSearch();
}
});
}
//updates the listUI whenever after receiving the response from the server
public void updateListUi(){
if(sResultsArr.size() > 0){
}
try{
String ptypename;
int count;
LinearLayout ptypebar = (LinearLayout)findViewById(R.id.productCat);
ptypebar.removeAllViews();
JSONArray ptypes = searchResponse.getJSONArray("ptypes");
for(int index =0;index < ptypes.length();index++){
JSONObject ptype = ptypes.getJSONObject(index);
count = ptype.getInt("count");
ptypename = ptype.getString("ptypename");
//add into tab 2's UI
//ImageView icon = new ImageView(this);
TextView t = new TextView(home.this);
t.setText(ptypename + " (" + count + ")");
ptypebar.addView(t);
}
}
catch(JSONException e){
}
//if(m_adapter.getItems() != sResultsArr){
ArrayList<SearchItem> a = m_adapter.getItems();
a = sResultsArr;
//}
m_adapter.notifyDataSetChanged();
pd.dismiss();
}
public void goSearch(){
mTabHost.setCurrentTab(1);
//separate thread for making http request and updating the arraylist
Thread t = new Thread() {
public void run() {
searchResponse = sendSearchQuery(queryStr);
try{
JSONArray results = searchResponse.getJSONArray("results");
//this is stupid. i probably have to see how to make a json adapter
for(int index =0;index < results.length();index++){
JSONObject product = results.getJSONObject(index);
//gets the searched products from the json object
URL imgUrl = new URL(product.getString("image"));
String productname = product.getString("productname");
String ptypename = product.getString("ptypename");
int pid = product.getInt("pid");
int positive = product.getInt("pos");
int negative = product.getInt("neg");
int neutral = product.getInt("neu");
SearchItem item = new SearchItem(imgUrl,productname,ptypename,neutral,positive,negative,pid);
sResultsArr.add(item);
}
}
catch(JSONException e){
}
catch(Exception e){
}
//returns back to UI therad
h.post(mUpdateResults);
}
};
t.start();
}
//sends a request with qry as URL
//and receives back a JSONobject as response
public JSONObject sendSearchQuery(String qry){
HttpRequest r = new HttpRequest();
JSONObject response = r.sendHttpRequest(qry);
return response;
}
@Override
public boolean onDown(MotionEvent arg0) {
return gestureScanner.onTouchEvent(arg0);
}
@Override
public boolean onFling(MotionEvent arg0, MotionEvent arg1, float arg2,
float arg3) {
// TODO Auto-generated method stub
return false;
}
@Override
public void onLongPress(MotionEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
float arg3) {
// TODO Auto-generated method stub
return false;
}
@Override
public void onShowPress(MotionEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public boolean onSingleTapUp(MotionEvent arg0) {
// TODO Auto-generated method stub
return false;
}
Oh, another question, if my ListView has an onItemClickListener, can android detect between single tap or double tap for it?
Answer
You can use the GestureDetector. See the following code:
public class MyView extends View {
GestureDetector gestureDetector;
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
// creating new gesture detector
gestureDetector = new GestureDetector(context, new GestureListener());
}
// skipping measure calculation and drawing
// delegate the event to the gesture detector
@Override
public boolean onTouchEvent(MotionEvent e) {
return gestureDetector.onTouchEvent(e);
}
private class GestureListener extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onDown(MotionEvent e) {
return true;
}
// event when double tap occurs
@Override
public boolean onDoubleTap(MotionEvent e) {
float x = e.getX();
float y = e.getY();
Log.d("Double Tap", "Tapped at: (" + x + "," + y + ")");
return true;
}
}
}
You can override other methods of the listener to get single taps, flinges and so on.