Now, I want to implement a function like this: at a activity, shield all hardware buttons, like HOME, VOLUME_UP,VOLUME_DOWM. But, only POWER button can't shield. Is there a way?
You cannot intercept certain keys in Android like power and home e.g. Home key cannot be intercepted as this will allow any malicious application to over ride the functionality.
The only way you can intercept the home key is if your application is the home app replacement itself by using android.intent.category.HOME in the manifest.
You can catch other keys e.g. volume up/down and back as follows
public boolean dispatchKeyEvent(KeyEvent event) {
int action = event.getAction();
int keyCode = event.getKeyCode();
switch (keyCode) {
case KeyEvent.KEYCODE_VOLUME_UP:
if (action == KeyEvent.ACTION_UP) {
//handle the key event
}
return true;
case KeyEvent.KEYCODE_VOLUME_DOWN:
if (action == KeyEvent.ACTION_DOWN) {
//handle the key event
}
return true;
default:
return super.dispatchKeyEvent(event);
}
}
Read the following post on the Android Developer blogpost
Android Developer: Back and other hard keys-three stories
Related
I am writing an Android App using Xamarin.Android.
I have to detect the hardware keyboard buttons (since my target device is a flip-phone), but I don't know how to do it in Xamarin.
In java it was something like this:
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch(keyCode)
{
case KeyEvent.KEYCODE_VOLUME_UP:
Toast.makeText(this, "Volume Up pressed", Toast.LENGTH_SHORT).show();
return true;
case KeyEvent.KEYCODE_VOLUME_DOWN:
Toast.makeText(this, "Volume Down pressed", Toast.LENGTH_SHORT).show();
return true;
}
return super.onKeyDown(keyCode, event);
}
Is there any way to detect/intercept keyboard buttons? some code example please?
Thank you all!
EDIT
I am looking for something that will allow me to have access to every single hardware button of the keyboard (1,2,3,4,5,6,7,8,9,0,#,*, call btn, endCall btn, etc.)
SECOND EDIT
Found what might be the problem...the code works perfectly, but since my app is a Launcher when I press number keys the dialer starts, any idea on how redirect the dialing to an activity I create?
Put this method in your activity:
public override bool OnKeyDown (Keycode keyCode, KeyEvent e)
{
switch (keyCode) {
case Keycode.VolumeUp:
Toast.MakeText (this, "Volume Up pressed", ToastLength.Long).Show ();
return true;
break;
case Keycode.VolumeDown:
Toast.MakeText (this, "Volume Down pressed", ToastLength.Long).Show ();
return true;
break;
}
return base.OnKeyDown (keyCode, e);
}
This is my final solution to intercept numpad keys on android devices. I hope this will help somebody else in the future.
[Activity(Label = "PhoneTask", LaunchMode = Android.Content.PM.LaunchMode.SingleTop)]
[IntentFilter(new[] { Intent.ActionDial, Intent.ActionCallButton, Intent.ActionView },
Categories = new[] { Intent.CategoryDefault },
DataScheme = "tel")]
Just added this piece of code above my activity class and now, when I press these buttons on a laucher app, I am redirected to my activity.
I was interested to know how can i catch key/button events from Android TV Box remote controller?
For example, i want a popup menu to show when i click the OK button from remote controller. And i want to catch the next/back key events from remote controller.
Should i use the Key Event class from Android, if yes how should i implement it?
I came across this function but i cannot really make sense of it.
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_A:
{
//your Action code
return true;
}
}
return super.onKeyDown(keyCode, event);
}
Thanks in advance.
You should catch key event on dispatchKeyEvent
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
Log.e(TAG, "Key down, code " + event.getKeyCode());
} else if (event.getAction() == KeyEvent.ACTION_UP) {
Log.e(TAG, "Key up, code " + event.getKeyCode());
}
return true;
}
Edit:
First, you should know key map of your remote (it is not the same for all kind of Android TV box), the code above will help you know code of key that you press on the remote. For example, i got key code 3 when i press button BACK on remote.
Then, i want when back key pressed, a Toast message will be show:
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
// You should make a constant instead of hard code number 3.
if (event.getAction() == KeyEvent.ACTION_UP && event.getKeyCode == 3) {
Toast.makeText(this, "Hello, you just press BACK", Toast.LENG_LONG).show();
}
return true;
}
Is it possible for an Android application to intercept external keyboard shortcuts (e.g. Alt+Tab) and action them before the OS performs the default behaviour? Using Alt+Tab as an example, I would like to be able to have my app respond to Alt+Tab within my application and not have Android switch applications to a different app.
I have tried searching, but have not been able to find an answer, I think my Google-Fu is failing me!
It maybe is not as extense or detailed as it would be needed for capturing a shortcut, but you may want to override the onKeyDown event in your activity.
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
Log.d(this.getClass().getName(), "Back button pressed");
}
if ((keyCode == KeyEvent.KEYCODE_HOME)) {
Log.d(this.getClass().getName(), "Home button pressed");
}
if ((keyCode == KeyEvent.KEYCODE_MENU)) {
Log.d(this.getClass().getName(), "Menu button pressed");
}
//return true;
return super.onKeyDown(keyCode, event);
}
I'm working on an input device that has a button that I'd like to act both as a home button when pressed by itself, but also work as a modifier for the other buttons on the device.
I know you can do this in the kcm file with other buttons, and have something like:
key ESCAPE {
base: fallback BACK
alt, meta: fallback HOME
ctrl: fallback MENU
}
Is it possible to have something like:
key CTRL_LEFT {
base: fallback HOME
{SOMETHING HERE}: CTRL_LEFT
}
so that I can press that button with another button and have it not fallback on HOME?
Thanks in advance! :D
This functionality is not possible on a system level: see
http://source.android.com/tech/input/key-character-map-files.html for a list of all options possible.
However, if you would like to have it on an application level, you could program it in as follows:
import android.view.KeyEvent;
private boolean home = false;
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (event.getScanCode() == 29) //29 == CTRL_LEFT
home = true; //if we release this button, HOME needs to be invoked
else home = false; //so CTRL_LEFT was used as a modifier: no need to invoke HOME
//allow the system to pass key handling to the next listener
return super.onKeyUp(keyCode, event);
}
public boolean onKeyUp(int keyCode, KeyEvent event)
{
if (event.getScanCode() == 29 && home == true)
{
super.dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_HOME));
return true; //so we absorb the event
}
return super.onKeyUp(keyCode, event);
}
Then, as long as this application is set up to receive the keystrokes (usually a privacy issue unless you're coding it in for yourself), it can process the keystrokes and dispatch the HOME button when need be.
Should you decide to proceed thus, you'd have to remove the
base: fallback HOME
from your code.
I'm a relative beginner with Android. Does anybody have a sane explanation for how to listen for keys and soft keys in an EditText/TextView?
I'd love to see a comprehensive tutorial or set of examples.
As I understand it, I can add a KeyListener to my Activity, e.g. onKeyDown(), onKeyUp() but when I try this I can't trigger the events for normal keys only HOME and BACK for example.
I have seen mention of using a TextWatcher but that isn't the same as handling raw key events.
There seem to be a number of half-solutions here on SO. Hoping you can help clear the mists of confusion...
You have to assign a key listener not to activity but rather to EditText itself.
This is what I have to listen to BACK or MENU key events. Simply add this method, without implementing any Interface. I do this in my BaseActivity, from which every Activity inherits.
public boolean onKeyDown(int keyCode, KeyEvent event) {
Log.d(NAME, "Key pressed");
switch (keyCode) {
case KeyEvent.KEYCODE_BACK:
Log.d(NAME, "Back pressed");
// IGNORE back key!!
return true;
/* Muestra el Menú de Opciones */
case KeyEvent.KEYCODE_MENU:
Intent menu = new Intent(this, Menu.class);
// start activity
startActivity(menu);
return true;
}
return super.onKeyDown(keyCode, event);
}
PS: I highly discourage ignoring the back key.
For example:
myEditText.setOnKeyListener(new OnKeyListener() {
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN)
if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER){
//your code here
}
return false;
}
});
I recently found another way that be stuck using Activity onKeyDown, or event setting a key listener on view (which is not really working with key events from ADB in my case) with view.setOnKeyListener.
Since android P method addOnUnhandledKeyEventListener has been introduced. It allows you to do whatever you need to do when your view is able to catch unhandled key events.
Here is an example of how I used it :
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) yourView.addOnUnhandledKeyEventListener { v, event ->
when (event.keyCode) {
KeyEvent.KEYCODE_UNKNOWN -> {
TODO("Do whatever you need to do.")
true // Specify you did handle the event
}
KeyEvent.KEYCODE_SOFT_RIGHT -> {
TODO("Do whatever you need to do.")
true // Specify you did handle the event
}
// etc...
else -> false // Specify you didn't handle the event
}
}