Android how to handle button click

Question

Having a solid experience in non-Java and non-Android area  I m learning Android   I have a  lot of confusion with different areas  one of them is how to handle button clicks  There are at least 4 way of doing that        they are briefly listed here  for consistency purpose I will list them    Have a member of the View OnClickListener class in the activity and assign it to an instance that will handle onClick logic in the onCreate activity method  Create  onClickListener  in the  onCreate  activity method and assign it to the button using setOnClickListener  Implement  onClickListener  in activity itself and assign  this  as a listener for the button  For the case if activity has few buttons  button id should be analyzed to execute  onClick  handler for the proper button Have public method on the activity that implements  onClick  logic and assign it to the button in the activity xml declaration   Question  1   Are those all methods  is there any other option   I don t need any other  just curious   For me  the most intuitive way would be the latest one  it requires the least amount of code to be typed and is the most readable  at least for me    Though  I don t see this approach used widely  What are cons for using it   Question  2   What are pros cons for each of these methods  Please share either your experience or a good link    Any feedback is welcome   P S  I ve tried to Google and find something for this topic  but the only things I ve found are description  how  to do that  not why is it good or bad

User · Accepted Answer

Question 1  Unfortunately the one in which you you say is most intuitive is the least used in Android  As I understand  you should separate your UI  XML  and computational functionality  Java Class Files   It also makes for easier debugging  It is actually a lot easier to read this way and think about Android imo  Question 2  I believe the two mainly used are  2 and  3  I will use a Button clickButton as an example  2 is in the form of an anonymous class  Button clickButton    Button  findViewById R id clickButton   clickButton setOnClickListener  new OnClickListener                               Override             public void onClick View v                       TODO Auto-generated method stub                    Do what you want with the click here                               This is my favorite as it has the onClick method right next to where the button variable was set with the findViewById  It seems very neat and tidy that everything that deals with this clickButton Button View is located here  A con that my coworker comments  is that imagine you have many views that need onclick listener  You can see that your onCreate will get very long in length  So that why he likes to use  3 Say you have  5 clickButtons  Make sure your Activity Fragment implement OnClickListener    in OnCreate  Button mClickButton1    Button findViewById R id clickButton1   mClickButton1 setOnClickListener this   Button mClickButton2    Button findViewById R id clickButton2   mClickButton2 setOnClickListener this   Button mClickButton3    Button findViewById R id clickButton3   mClickButton3 setOnClickListener this   Button mClickButton4    Button findViewById R id clickButton4   mClickButton4 setOnClickListener this   Button mClickButton5    Button findViewById R id clickButton5   mClickButton5 setOnClickListener this        somewhere else in your code  public void onClick View v        switch  v getId              case  R id clickButton1                   do something for button 1 click             break                     case R id clickButton2                   do something for button 2 click             break                            etc          This way as my coworker explains is neater in his eyes  as all the onClick computation is handled in one place and not crowding the onCreate method  But the downside I see is  that the   views themselves  and any other object that might be located in onCreate used by the onClick method will have to be made into a field   Let me know if you would like more information  I didn t answer your question fully because it is a pretty long question  And if I find some sites I will expand my answer  right now I m just giving some experience

User · Answer

To make things easier asp Question 2 stated  you can make use of lambda method like this to save variable memory and to avoid navigating up and down in your view class    method 1 findViewById R id buttonSend  setOnClickListener v - gt                 handle click       but if you wish to apply click event to your button at once in a method   you can make use of Question 3 by  D  Tran answer  But do not forget to implement your view class with View OnClickListener    In other to use Question  3 properly

User · Answer

Option 1 and 2 involves using inner class that will make the code kind of clutter   Option 2 is sort of messy because there will be one listener for every button  If you have small number of button  this is okay  For option 4 I think this will be harder to debug as you will have to go back and fourth the xml and java code  I personally use option 3 when I have to handle multiple button clicks

User · Answer

There are also options available in the form of various libraries that can make this process very familiar to people that have used other MVVM frameworks   https   developer android com topic libraries data-binding   Shows an example of an official library  that allows you to bind buttons like this    lt Button     android text  Start second activity      android layout width  match parent      android layout height  wrap content      android onClick       - gt  presenter showList       gt

User · Answer

Step 1 Create an XML File    lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout     xmlns android  http   schemas android com apk res android      android layout width  match parent      android layout height  match parent      android orientation  vertical  gt        lt Button         android id    id btnClickEvent          android layout width  wrap content          android layout height  wrap content          android text  Click Me    gt   lt  LinearLayout gt    Step 2 Create MainActivity   package com scancode acutesoft telephonymanagerapp   import android app Activity  import android os Bundle  import android view View  import android widget Button   public class MainActivity extends Activity implements View OnClickListener        Button btnClickEvent       Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity main            btnClickEvent    Button  findViewById R id btnClickEvent           btnClickEvent setOnClickListener MainActivity this                Override     public void onClick View v              Your Logic           HappyCoding

User · Answer

Most used way is  anonymous declaration      Button send    Button  findViewById R id buttonSend       send setOnClickListener new View OnClickListener              Override         public void onClick View v                   handle click                     Also you can create View OnClickListener object and set it to button later  but you still need to override onClick method for example  View OnClickListener listener   new View OnClickListener          Override         public void onClick View v                   handle click                Button send    Button  findViewById R id buttonSend   send setOnClickListener listener     When your activity implements OnClickListener interface you must override onClick View v    method on activity level  Then you can assing this activity as listener to button  because it already implements interface and overrides the onClick   method  public class MyActivity extends Activity implements View OnClickListener         Override     public void onClick View v               handle click              Override     public void onCreate Bundle b            Button send    Button  findViewById R id buttonSend           send setOnClickListener this               imho  4-th approach used when multiple buttons have same handler  and you can declare one method in activity class and assign this method to multiple buttons in xml layout  also you can create one method for one button  but in this case I prefer  to declare handlers inside activity class

User · Answer

1 I use the last one frequently when having buttons on the layout which are not generated  but static obviously    If you use it in practice and in a business application  pay extra attention here  because when you use source obfuscater like ProGuard  you ll need to mark these methods in your activity as to not be obfuscated   For archiving some kind of compile-time-security with this approach  have a look at Android Lint  example       2 Pros and cons for all methods are almost the same and the lesson should be      Use what ever is most appropriate or feels most intuitive to you    If you have to assign the same OnClickListener to multiple button instances  save it in the class-scope   1   If you need a simple listener for a Button  make an anonymous implementation   button setOnClickListener new View OnClickListener          Override     public void onClick View view               Take action              I tend to not implement the OnClickListener in the activity  this gets a little confusing from time to time  especially when you implement multiple other event-handlers and nobody knows what this is all doing

User · Answer

I prefer option 4  but it makes intuitive sense to me because I do far too much work in Grails  Groovy  and JavaFX    Magic  connections between the view and the controller are common in all   It is important to name the method well   In the view add the onClick method to the button or other widget       android clickable  true      android onClick  onButtonClickCancel    Then in the class  handle the method   public void onButtonClickCancel View view        Toast makeText this   Cancel pressed   Toast LENGTH LONG  show        Again  name the method clearly  something you should do anyway  and the maintenance becomes second-nature   One big advantage is that you can write unit tests now for the method   Option 1 can do this  but 2 and 3 are more difficult

User · Answer

My sample  Tested in Android studio 2 1  Define button in xml layout   lt Button     android id    id btn1      android layout width  wrap content      android layout height  wrap content    gt    Java pulsation detect  Button clickButton    Button  findViewById R id btn1   if  clickButton    null        clickButton setOnClickListener  new View OnClickListener               Override         public void onClick View v                    Do what you want with the click here

User · Answer

Question 1 - These are the only way to handle view clicks    Question 2 - Option 1 Option 4 - There s not much difference between option 1 and option 4  The only difference I see is in one case activity is implementing the OnClickListener  whereas  in the other case  there d be an anonymous implementation   Option 2 - In this method an anonymous class will be generated  This method is a bit cumborsome  as  you d need to do it multiple times  if you have multiple buttons  For Anonymous classes  you have to be careful for handling memory leaks   Option 3 - Though  this is a easy way  Usually  Programmers try not to use any method until they write it  and hence this method is not widely used  You d see mostly people use Option 4  Because it is cleaner in term of code

[java] Android: how to handle button click

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