Android OnClickListener - identify a button

Question

I have the activity   public class Mtest extends Activity     Button b1    Button b2    public void onCreate Bundle savedInstanceState                b1    Button  findViewById R id b1       b2    Button  findViewById R id b2       b1 setOnClickListener myhandler       b2 setOnClickListener myhandler                 View OnClickListener myhandler   new View OnClickListener         public void onClick View v             MY QUESTION STARTS HERE             IF b1 do this          IF b2 do this          MY QUESTION ENDS HERE                  How do I check which button has been clicked

User · Accepted Answer

You will learn the way to do it  in an easy way  is   public class Mtest extends Activity     Button b1    Button b2    public void onCreate Bundle savedInstanceState                b1    Button  findViewById R id b1       b2    Button  findViewById R id b2       b1 setOnClickListener myhandler1       b2 setOnClickListener myhandler2                 View OnClickListener myhandler1   new View OnClickListener         public void onClick View v             it was the 1st button              View OnClickListener myhandler2   new View OnClickListener         public void onClick View v             it was the 2nd button                Or  if you are working with just one clicklistener  you can do   View OnClickListener myOnlyhandler   new View OnClickListener       public void onClick View v          switch v getId              case R id b1               it was the first button           break          case R id b2               it was the second button           break                  Though  I don t recommend doing it that way since you will have to add an if for each button you use  That s hard to maintain

User · Answer

The best way is by switch-ing between v getId    Having separate anonymous OnClickListener for each Button is taking up more memory  Casting View to Button is unnecessary  Using if-else when switch is possible is slower and harder to read  In Android s source you can often notice comparing the references by if-else   if  b1    v              else if  b2    v      I don t know exactly why they chose this way  but it works too

User · Answer

In addition to Cristian C s answer  sorry  I do not have the ability to make comments   if you make one handler for both buttons  you may directly compare v to b1 and b2  or if you want to compare by the ID  you do not need to cast v to Button  View has getId   method  too   and that way there is no worry of cast exception

User · Answer

Or you can try the same but without listeners  On your button XML definition   android onClick  ButtonOnClick    And in your code define the method ButtonOnClick   public void ButtonOnClick View v        switch  v getId            case R id button1          doSomething1            break        case R id button2          doSomething2            break

User · Answer

Button button1    Button findViewById R id button1   button1 setOnClickListener this     Override public void onClick View v           TODO Auto-generated method stub     if v getId      R id button1           Toast makeText context   Button 1 Click   Toast LENGTH LONG  show              Check this article for more details

User · Answer

If you don t want to save instances of the 2 button in the class code  follow this BETTER way  this is more clear and fast       public void buttonPress View v      switch  v getId          case R id button one             do something         break      case R id button two             do something else         break      case R id button three             i m lazy  do nothing         break

User · Answer

Another way of doing it is a single listener from activity   like this   public class MyActivity extends Activity implements OnClickListener                code        my listener      Override     public void onClick View v            if  v getId      R id mybutton                 DoSomething                return                     if  v getId      R id mybutton2                 DoSomething2                return                      I Like to do it with single IF instead of switch-else  but if you prefer that  then you should do     my listener  Override public void onClick View v        switch v getId              case R id mybutton                          DoSomething                 break                     case R id mybutton2                        DoSomething                break

User · Answer

use setTag     like this    Override     public void onClick View v             int tag    Integer  v getTag             switch  tag             case 1               System out println  button1 click                 break           case 2               System out println  button2 click                break

User · Answer

Button mybutton   new Button ViewPagerSample this   mybutton setOnClickListener new OnClickListener          Override     public void onClick View v                   TODO Auto-generated method stub

User · Answer

I prefer   class MTest extends Activity implements OnClickListener       public void onCreate Bundle savedInstanceState                Button b1    Button  findViewById R id b1       Button b2    Button  findViewById R id b2       b1 setOnClickListener this       b2 setOnClickListener this               And then    Override public void onClick View v        switch  v getId              case R id b1                               break          case R id b2                               break               Switch-case is easier to maintain than if-else  and this implementation doesn t require making many class variables

User · Answer

Five Ways to Wire Up an Event Listener is a great article overviewing the various ways to set up a single event listener  Let me expand that here for multiple listeners   1  Member Class  public class main extends Activity        Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main             attach an instance of HandleClick to the Button         HandleClick handleClick   new HandleClick            findViewById R id button1  setOnClickListener handleClick           findViewById R id button2  setOnClickListener handleClick                 private class HandleClick implements OnClickListener          public void onClick View view                switch view getId                  case R id button1                     do stuff                 break              case R id button2                     do stuff                 break                                    2  Interface Type  public class main extends Activity        Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main           findViewById R id button1  setOnClickListener handleClick           findViewById R id button2  setOnClickListener handleClick             private OnClickListener handleClick   new OnClickListener             public void onClick View view                switch  view getId                  case R id button1                     do stuff                 break              case R id button2                     do stuff                 break                                     3  Anonymous Inner Class  public class main extends Activity        Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main           findViewById R id button1  setOnClickListener new OnClickListener                 public void onClick View view                       do stuff                                   findViewById R id button2  setOnClickListener new OnClickListener                 public void onClick View view                       do stuff                                     4  Implementation in Activity  public class main extends Activity implements OnClickListener        Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main           findViewById R id button1  setOnClickListener this           findViewById R id button2  setOnClickListener this             public void onClick View view            switch  view getId              case R id button1                 do stuff             break          case R id button2                 do stuff             break                      5  Attribute in View Layout for OnClick Events  public class main extends Activity        Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main             public void HandleClick View view            switch  view getId              case R id button1                 do stuff             break          case R id button2                 do stuff             break                      And in xml    lt Button     android id    id button1      android layout width  wrap content      android layout height  wrap content      android onClick  HandleClick    gt   lt Button     android id    id button2      android layout width  wrap content      android layout height  wrap content      android onClick  HandleClick    gt

[android] Android OnClickListener - identify a button

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