I want to know how to add multiple click events to buttons defined in XML, as previously, in Java, we implemented View.onClickListener interface and did the rest of the work in onClick method.
Example:
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.oneButton:
// do your code
break;
case R.id.twoButton:
// do your code
break;
case R.id.threeButton:
// do your code
break;
default:
break;
}
}
I'm making a basic calculator app with the new Kotlin but it seems Kotlin has no such provisions, instead my code looks too long and verbose, as I'm attaching events to all buttons individually.
Can someone tell me how to do the same way in Kotlin? Thanks
For multiple onClickListeners in kotlin (version:1.1.60), the following helped me. Hope it'll be useful to someone else too.
Implement OnClickListener to activity like:
class YourActivity : AppCompatActivity(), View.OnClickListener
set your button in onCreate():
val button = findViewById<Button>(R.id.buttonId)
and assign onclick to the button in onCreate():
button.setOnClickListener { onClick(button) }
and in the override method of onClick() :
override fun onClick(v: View) {
when (v.id) {
R.id.buttonId -> { //your code }
..
..
..
else -> { //your code }
}
}
Yes, in Kotlin you can do it like this:
view.setOnClickListener(object : View.OnClickListener {
override fun onClick(v: View?) {
when(v?.id) {
R.id.imgBack -> {/* do your code */}
R.id.twoButton -> {/* do your code */}
R.id.threeButton -> {/* do your code */}
else -> {/* do your code */}
}
}
}
You can try this following code:
class Testing:AppCompatActivity(), View.OnClickListener {
private val mButton1:Button
private val mButton2:Button
protected fun onCreate(savedInstanceState:Bundle) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_testing)
mButton1 = findViewById(R.id.btn_click) as Button
mButton2 = findViewById(R.id.btn_click1) as Button
mButton1.setOnClickListener(this)
mButton2.setOnClickListener(this)
}
fun onClick(view:View) {
when (view.getId()) {
R.id.btn_click -> {
Toast.makeText(this, "button 1", Toast.LENGTH_SHORT).show()
}
R.id.btn_click1 -> {
Toast.makeText(this, "button 2", Toast.LENGTH_SHORT).show()
}
else -> {}
}
}
}
I hope this is help you.
First of all implement OnClickListener in your Activity, like
class MainActivity : Activity , OnClickListener
then override its implementation like
func onClick(v:View) {
//use when here like
case R.id.youview -> {
// do your work on click of view
}
Don't forgot to set clicklistener on your View.
yourView.setOnClickListener(this)
Or for better understanding go step by step -
Implement OnClickListener in your Activity.
Compiler will ask you to implement overrided methods. Implement those.
Copy paste your java code which you wrote inside onClick method, that can be converted by kotlin itself or write down when conditions.
This code worked for me:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
imgBack.setOnClickListener(this)
twoButton.setOnClickListener(this)
threeButton.setOnClickListener(this)
}
override fun onClick(view:View) {
when (view.id) {
R.id.imgBack -> {
Toast.makeText(this, "imgBack", Toast.LENGTH_SHORT).show()
}
R.id.twoButton -> {
Toast.makeText(this, "twoButton", Toast.LENGTH_SHORT).show()
}
else -> {}
}
}
Don't forget implement View.OnClickListener in your class.
you can create anonymous object from an inteface View.ClickListener and pass it to setOnClickListener function
private val clickListener = View.OnClickListener { p0 ->
when (p0.id) {
....
}
}
... setOnClickListener(clickListener)
Try below like this.
public class MainActivity extends Activity implements View.OnClickListener{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Button xyz = (Button) findViewById(R.id.xyz);
xyz.setOnClickListener(this);
}
#Override
public void onClick(View v) {
}}
More detailed information at https://androidacademic.blogspot.in/2016/12/multiple-buttons-onclicklistener-android.html
Related
I've seen plenty of answers explaining how to override and add functionality to a back button press via user's interaction, but almost none of the answers explain how to programmatically trigger a back button press without any user input. Answers that do address it give somewhat deprecated code samples that don't really compute.
From your activity just call => onBackPressed(),
or form your fragment => activity?.onBackPressed()
//simply put this code where you want to make back intent
super.onBackPressed();
According to official docs onBackPressed is deprecated in Api level 33.
you can now use onBackPressedDispatcher please follow these steps:
Add android:enableOnBackInvokedCallBack="true” inside application tag
in manifest folder.
Kotlin code :
class YourActivity : AppCompatActivity() {
lateinit var button: Button
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button = findViewById(R.id.txt)
button.setOnClickListener {
onBackPressedCallback.handleOnBackPressed()
}
}
private val onBackPressedCallback = object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
finish() //this finishes the current activity
// Your business logic to handle the back pressed event
}
}
}
And here is old way of implementation:
Java :
buttonBack.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
YourActivity.super.onBackPressed();
}
});
Kotlin :
buttonBack.setOnClickListener{
super.onBackPressed()
}
I'm using PreferenceFragmentCompat to display and set SharedPreferences. This all works fine. However, I keep getting "W/InputEventReceiver: Attempted to finish an input event but the input event receiver has already been disposed." in my logs, because the standard dialog used by PreferencesFragmentCompat does not seem to use the .setCancelable(false) in its showDialog method. I guess I could build my own custom dialog, but that seems a bit of an overkill just to solve this one small problem. Is there any way to simply overwrite the method?
Update:
It was enough to add this to my PreferencesFragmet (removed MultiSelectListPreferenceDialogFragmentCompat, as I don't use it)
#Override
public void onDisplayPreferenceDialog(Preference pref) {
DialogFragment dialogFragment = null;
String DIALOG_FRAGMENT_TAG = "androidx.preference.PreferenceFragment.DIALOG";
if (pref instanceof EditTextPreference) {
dialogFragment = EditTextPreferenceDialogFragmentCompat.newInstance(pref.getKey());
} else if (pref instanceof ListPreference) {
dialogFragment = ListPreferenceDialogFragmentCompat.newInstance(pref.getKey());
}
if (dialogFragment != null) {
dialogFragment.setTargetFragment(this, 0);
dialogFragment.setCancelable(false); //adding this!
if (this.getFragmentManager() != null) {
dialogFragment.show(this.getFragmentManager(), DIALOG_FRAGMENT_TAG);
}
} else {
super.onDisplayPreferenceDialog(pref);
}
}
I sorted though PreferenceFramgnetCompat source code to solve this issue.
Unfortunately, you can't execute '.setCancelable(false)' to dialog without callback or override.
I'll explain it with callback.
You should implement 'PreferenceFragmentCompat.OnPreferenceDisplayDialogCallback' interface on activity which contains PreferenceFragmentCompat fragment.
When user press a preference one of EditTextPreference, ListPreference or AbstractMultiSelectListPreference, the onPreferenceDisplayDialog method will be executed.
When onPreferenceDisplayDialog method is executed, you should open dialog.
Fortunately, there are three type dialog and Google provide it by public so you don't need to make a custom dialog for them.
Just create instance of dialog and call setCancelable(false) and show it!
Please refer below codes.
class SettingsActivity : FragmentActivity(), PreferenceFragmentCompat.OnPreferenceDisplayDialogCallback {
private val DIALOG_FRAGMENT_TAG = "android.support.v7.preference.PreferenceFragment.DIALOG"
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
supportFragmentManager.beginTransaction()
.replace(android.R.id.content, SettingsFragment(), "setting_fragment").commit()
}
override fun onPreferenceDisplayDialog(caller: PreferenceFragmentCompat, preference: Preference?): Boolean {
// check if dialog is already showing
if (supportFragmentManager!!.findFragmentByTag(DIALOG_FRAGMENT_TAG) != null) {
return true
}
val f: DialogFragment
if (preference is EditTextPreference) {
f = EditTextPreferenceDialogFragmentCompat.newInstance(preference.getKey())
} else if (preference is ListPreference) {
f = ListPreferenceDialogFragmentCompat.newInstance(preference.getKey())
} else if (preference is AbstractMultiSelectListPreference) {
f = MultiSelectListPreferenceDialogFragmentCompat.newInstance(preference.getKey())
} else {
throw IllegalArgumentException("Tried to display dialog for unknown " + "preference type. Did you forget to override onDisplayPreferenceDialog()?")
}
f.setTargetFragment(supportFragmentManager.findFragmentByTag("setting_fragment"), 0)
f.isCancelable = false // !! HERE !!
f.show(supportFragmentManager!!, DIALOG_FRAGMENT_TAG)
return true
}
}
How can I display panel states of SlidingUpPanel in Kotlin?
I want to use https://github.com/umano/AndroidSlidingUpPanel library, following this tutorial:
http://www.devexchanges.info/2015/05/making-sliding-up-panel-like-google.html
and the result should look like this:
https://www.youtube.com/watch?v=g464fp-2dQU
The code in Java from tutorial link:
private SlidingUpPanelLayout.PanelSlideListener onSlideListener() {
return new SlidingUpPanelLayout.PanelSlideListener() {
#Override
public void onPanelSlide(View view, float v) {
textView.setText("panel is sliding");
}
#Override
public void onPanelCollapsed(View view) {
textView.setText("panel Collapse");
}
#Override
public void onPanelExpanded(View view) {
textView.setText("panel expand");
}
#Override
public void onPanelAnchored(View view) {
textView.setText("panel anchored");
}
#Override
public void onPanelHidden(View view) {
textView.setText("panel is Hidden");
}
};
}
The converted code from Java to Kotlin (I put toast from anko library instead of textView):
private fun onSlideListener(): SlidingUpPanelLayout.PanelSlideListener {
return object : SlidingUpPanelLayout.PanelSlideListener {
override fun onPanelSlide(view: View, v: Float) {
toast("panel is sliding")
}
override fun onPanelCollapsed(view: View) {
toast("panel Collapse")
}
override fun onPanelExpanded(view: View) {
toast("panel expand")
}
override fun onPanelAnchored(view: View) {
toast("panel anchored")
}
override fun onPanelHidden(view: View) {
toast("panel is Hidden")
}
}
}
In Java code, in onCreate method, I have:
slidingLayout.setPanelSlideListener(onSlideListener());
which doesn't seems to work in Kotlin, because the methods I have are Click, Drag, Hover, Key and Touch (listeners).
I guess other good approach could be to implement
SlidingPaneLayout.PanelSlideListener
on my class, but I still couldn't make it work.
Any solution to find up if the panel is displayed or hidden in Kotlin?
You need to load up the Slidinglayout.
private lateinit var slidingLayout: SlidingUpPanelLayout
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.activity_main, container, false).also {
slidingLayout = it.findViewById(R.id.sliding_Layout)
}
}
than you check for the PanelState
if (slidingLayout.panelState == SlidingUpPanelLayout.PanelState.HIDDEN)
You also have the states ANCHORED, EXPANDED, COLLAPSED, DRAGGING
If you want to set up the Listener in Kotlin I have done it like This.
slidingLayout.addPanelSlideListener(object : SlidingUpPanelLayout.PanelSlideListener {
override fun onPanelSlide(panel: View?, slideOffset: Float) {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
override fun onPanelStateChanged(panel: View?, previousState: SlidingUpPanelLayout.PanelState?, newState: SlidingUpPanelLayout.PanelState?) {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
})
I have been looking for my question on Google and inside the forum but I cannot an answer so far. I am using android studio to code an app in Java
The thing is : inside a class, I have overrided the OnClick() method because I have to implement a lot of views.
Now I want to call a function just before OnClick() is called.
What I mean is, for instance, if the user taps on a button, before OnClick() is called I want one of my methods to be called.
Does anyone know how to do this ?
Thank you in advance
I want to call a function just before OnClick() is called
You can use a logic inside onClick() like,
if(userhaspermission())//your method to check if the user has permission
{
//your onclick operation code
}
Make your checking permission method with return type as boolean
Implement your custom OnClickListener as follows
public abstract class MyOnClickListener implements OnClickListener {
#Override
public void onClick(View v) {
//Do common action
if(condidtionSatisfied){
performClick(v);
}
}
public abstract void performClick(View v);
}
Set onClickListener to any component as follows:
button.setOnClickListener(new MyOnClickListener() {
#Override
public void performClick(View v) {
//Execute post click action
}
});
This will ensure your common code will be called for all the views and it would be much cleaner approach.
Override the onClick() method and write your first logic which you want.
Write your own Listener like Sagar said
This logic is quite similar to Sagar's Answers.
Write abstract class as given below
public abstract class OnClick implements View.OnClickListener {
public void beforeClick(View v) {
}
#Override
public void onClick(View v) {
beforeClick(v);
performClick(v);
afterClick(v);
}
public void performClick(View v) {
}
public void afterClick(View v) {
}
}
NOTE : See in above code it implements View.OnClickListener, so this logic will works for views which extends View super class. If you want above logic for object's which needs Dialog interface onClick then you need to modify it for DialogInterface.OnClickListener.
So you can use above logic as below
//Let say you need it for button with id button
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new OnClick() {
#Override
public void beforeClick(View v) {
Toast.makeText(MainActivity.this, "Before", Toast.LENGTH_SHORT).show();
}
#Override
public void performClick(View v) {
Toast.makeText(MainActivity.this, "Click", Toast.LENGTH_SHORT).show();
}
#Override
public void afterClick(View v) {
Toast.makeText(MainActivity.this, "After", Toast.LENGTH_SHORT).show();
}
});
Always in my apps I added buttons in void onCreate, but now I'm trying to do app with more buttons (about 10). I would like to all buttons active on start app.
In my opinion it is too much buttons to add in this onCreate and app will be starting to long.
I tried to put this:
myButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
myMethod();
}
})
out of onCreate
but AndroidStudio underlines setOnClickListener and view
I don't have ideas, how and where can i add button out of onCreate.
If you don't want to overcrowd your oncreate method, then create a clicklistener outside onCreate anywhere in activity and in onCreate just set it.
onCreate :
edit_a_member = (Button) findViewById(R.id.edit_member);
delete_a_member = (Button) findViewById(R.id.delete_member);
edit_a_member.setOnClickListener(handleClick);
delete_a_member.setOnClickListener(handleClick);
clickListener:
private View.OnClickListener handleClick = new View.OnClickListener() {
#Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.edit_member:
member_selected = EDIT_MEMBER_SELECTED;
callDialog();
break;
case R.id.delete_member:
callDeleteAlert();
break;
}
}
};
You can simply add a separate method for your buttons in the same class, e.g.:
public void onCreate(...){
//Standard setup of views or whatever you want to do here
this.addButtons();
}
private void addButtons(){
Button b1 = new Button("Hi");
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
myMethod();
}
});
Button b2 = new Button("Hi to you too");
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
myMethod();
}
});
}
This is an example. You can do this in soooo many ways. I feel like you should thoroughly learn Java's fundamental Object Oriented programming, because that's really what your question suggests you don't understand. Go follow a youtube tutorial. I always like "The New Boston"'s Java tutorial series on youtube.
PS: You can make code like this beautiful under the 'Words of wisdom': Don't repeat yourself
If you have to do a lot of work in your onCreate but you are worried that the UI will take too long to load you can always post a delayed runnable to a handler so in the onCreate method put :
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
//add your code here
}
},10);
what this will do is your UI will load then the code in your Runnable will be executed 10 milliseconds after your UI loads thus your app will not take too long to load the UI, even though in your case I doubt it would be necessary.
If you are declaring the buttons in xml file :
Add these properties in each button Declaration in your Xml :
android:clickable="true"
android:onClick="onClick"
And now in Activity Class create a method like this :
public void onClick(View v){
switch(v.getId){
case R.id.{buttons_id_in_xml}
(Your Code)
break;
(Like for others)
}
}
If you want to add buttons dynamically :
Create a method to add the button like this:
void addButton(String buttonName, int button id){
Button button = new Button(this);
button.setText("Push Me");
(add it to parent Layout of xml)
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
switch(id){
case id1:
(handle )
break;
(like for others)
}
}
});
}
The best way to do this is:
add implements View.OnClickListener to
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
// declare variables
private Button mBtn1;
private Button mBtn2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
// make an instance to the btns
mBtn1 = findViewById(R.id.btn1);
mBtn2 = findViewById(R.id.btn2);
// set onClickListener
mBtn1.setOnClickListener(this); // with "this" you are passing the view
mBtn2.setOnClickListener(this);
}
// implement onClick
#Override
public void onClick(View view) {
// check which btn was clicked by id
switch (view.getId()) {
case R.id.btn1:
btn1Clicked();
break;
case R.id.btn2:
btn2Clicked();
break;
}
}
private void btn1Clicked() {
// your code btn1 clicked
}
private void btn2Clicked() {
// your code btn2 clicked
}
Hope this helped. Cheers!