Intercept back button from soft keyboard

onKeyDown() and onBackPressed() doesn't work for this case. You have to use onKeyPreIme.

Initially, you have to create custom edit text that extends EditText. And then you have to implement onKeyPreIme method which controls KeyEvent.KEYCODE_BACK. After this, one back press enough for solve your problem. This solution works for me perfectly.

CustomEditText.java

public class CustomEditText extends EditText {

    public CustomEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onKeyPreIme(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            // User has pressed Back key. So hide the keyboard
            InputMethodManager mgr = (InputMethodManager)         

           getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            mgr.hideSoftInputFromWindow(this.getWindowToken(), 0);
            // TODO: Hide your view as you do it in your activity
        }
        return false;
}

In your XML

<com.YOURAPP.CustomEditText
     android:id="@+id/CEditText"
     android:layout_height="wrap_content"
     android:layout_width="match_parent"/> 

In your Activity

public class MainActivity extends Activity {
   private CustomEditText editText;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      editText = (CustomEditText) findViewById(R.id.CEditText);
   }
}

I had success by overriding dispatchKeyEvent:

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
        finish();
        return true;
    }
    return super.dispatchKeyEvent(event);
}

It hides the keyboard and finishes the activity.

Yes, it is completely possible to show and hide the keyboard and intercept the calls to the back button. It is a little extra effort as it has been mentioned there is no direct way to do this in the API. The key is to override boolean dispatchKeyEventPreIme(KeyEvent) within a layout. What we do is create our layout. I chose RelativeLayout since it was the base of my Activity.

<?xml version="1.0" encoding="utf-8"?>
<com.michaelhradek.superapp.utilities.SearchLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res/com.michaelhradek.superapp"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/white">

Inside our Activity we set up our input fields and call the setActivity(...) function.

private void initInputField() {
    mInputField = (EditText) findViewById(R.id.searchInput);        

    InputMethodManager imm = 
        (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE); 
    imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 
            InputMethodManager.HIDE_IMPLICIT_ONLY);

    mInputField.setOnEditorActionListener(new OnEditorActionListener() {

        @Override
        public boolean onEditorAction(TextView v, int actionId,
                KeyEvent event) {
            if (actionId == EditorInfo.IME_ACTION_SEARCH) {
                performSearch();
                return true;
            }

            return false;
        }
    });

    // Let the layout know we are going to be overriding the back button
    SearchLayout.setSearchActivity(this);
}

Obviously, the initInputField() function sets up the input field. It also enables the enter key to execute the functionality (in my case a search).

@Override
public void onBackPressed() {
    // It's expensive, if running turn it off.
    DataHelper.cancelSearch();
    hideKeyboard();
    super.onBackPressed();
}

So when the onBackPressed() is called within our layout we then can do whatever we want like hide the keyboard:

private void hideKeyboard() {
    InputMethodManager imm = (InputMethodManager) 
        getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(mInputField.getWindowToken(), 0);
}

Anyway, here is my override of the RelativeLayout.

package com.michaelhradek.superapp.utilities;

import android.app.Activity;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.RelativeLayout;

/**
 * The root element in the search bar layout. This is a custom view just to 
 * override the handling of the back button.
 * 
 */
public class SearchLayout extends RelativeLayout {

    private static final String TAG = "SearchLayout";

    private static Activity mSearchActivity;;

    public SearchLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SearchLayout(Context context) {
        super(context);
    }

    public static void setSearchActivity(Activity searchActivity) {
        mSearchActivity = searchActivity;
    }

    /**
     * Overrides the handling of the back key to move back to the 
     * previous sources or dismiss the search dialog, instead of 
     * dismissing the input method.
     */
    @Override
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        Log.d(TAG, "dispatchKeyEventPreIme(" + event + ")");
        if (mSearchActivity != null && 
                    event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
            KeyEvent.DispatcherState state = getKeyDispatcherState();
            if (state != null) {
                if (event.getAction() == KeyEvent.ACTION_DOWN
                        && event.getRepeatCount() == 0) {
                    state.startTracking(event, this);
                    return true;
                } else if (event.getAction() == KeyEvent.ACTION_UP
                        && !event.isCanceled() && state.isTracking(event)) {
                    mSearchActivity.onBackPressed();
                    return true;
                }
            }
        }

        return super.dispatchKeyEventPreIme(event);
    }
}

Unfortunately I can't take all the credit. If you check the Android source for the quick SearchDialog box you will see where the idea came from.

I found out, that overriding the dispatchKeyEventPreIme method of the Layout Class also works well. Just set your main Activity as an attribute and launch a predefined method.

public class LinearLayoutGradient extends LinearLayout {
    MainActivity a;

    public void setMainActivity(MainActivity a) {
        this.a = a;
    }

    @Override
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        if (a != null) {
            InputMethodManager imm = (InputMethodManager) a
                .getSystemService(Context.INPUT_METHOD_SERVICE);

            if (imm.isActive() && event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
                a.launchMethod;
            }
        }

        return super.dispatchKeyEventPreIme(event);
    }
}