changing the language while typing a word now automatically updates the suggestion list with new words, instead of clearing it

app/src/main/java/io/github/sspanak/tt9/ime/TraditionalT9.java

@@ -30,6 +30,7 @@ import io.github.sspanak.tt9.ime.modes.ModePassthrough;
 import io.github.sspanak.tt9.ime.modes.ModePredictive;
 import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.languages.LanguageCollection;
+import io.github.sspanak.tt9.languages.Text;
 import io.github.sspanak.tt9.preferences.SettingsStore;
 import io.github.sspanak.tt9.preferences.helpers.Hotkeys;
 import io.github.sspanak.tt9.ui.PopupDialogActivity;
@@ -486,15 +487,17 @@ public class TraditionalT9 extends KeyPadHandler {
 		}
 
 		cancelAutoAccept();
-		commitCurrentSuggestion(false);
-		resetKeyRepeat();
 		nextLang();
 		mInputMode.changeLanguage(mLanguage);
-		mInputMode.reset();
+		mInputMode.clearWordStem();
+		getSuggestions();
 
 		statusBar.setText(mInputMode.toString());
 		mainView.render();
 		forceShowWindowIfHidden();
+		if (!suggestionBar.isEmpty()) {
+			UI.toastLanguage(this, mLanguage);
+		}
 
 		if (mInputMode instanceof ModePredictive) {
 			DictionaryLoader.autoLoad(this, mLanguage);
@@ -658,6 +661,15 @@ public class TraditionalT9 extends KeyPadHandler {
 		// display the word suggestions
 		setSuggestions(mInputMode.getSuggestions());
 
+		// In case we are here, because the language was changed, and there were words for the old language,
+		// but there are no words for the new language, we'll get only generated suggestions, consisting
+		// of the last word of the previous language + endings from the new language. These words are invalid,
+		// so we discard them.
+		if (mInputMode instanceof ModePredictive && !mLanguage.isValidWord(suggestionBar.getCurrentSuggestion()) && !Text.isGraphic(suggestionBar.getCurrentSuggestion())) {
+			mInputMode.reset();
+			setSuggestions(null);
+		}
+
 		// flush the first suggestion, if the InputMode has requested it
 		if (scheduleAutoAccept(mInputMode.getAutoAcceptTimeout())) {
 			return;

app/src/main/java/io/github/sspanak/tt9/ime/modes/ModeABC.java

@@ -29,8 +29,8 @@ public class ModeABC extends InputMode {
 			reset();
 			autoAcceptTimeout = 0;
 			digitSequence = String.valueOf(number);
-			suggestions.add(language.getKeyNumber(number));
 			shouldSelectNextLetter = false;
+			suggestions.add(language.getKeyNumber(number));
 		} else if (repeat > 0) {
 			autoAcceptTimeout = settings.getAbcAutoAcceptTimeout();
 			shouldSelectNextLetter = true;
@@ -38,9 +38,9 @@ public class ModeABC extends InputMode {
 			reset();
 			autoAcceptTimeout = settings.getAbcAutoAcceptTimeout();
 			digitSequence = String.valueOf(number);
+			shouldSelectNextLetter = false;
 			suggestions.addAll(language.getKeyCharacters(number));
 			suggestions.add(language.getKeyNumber(number));
-			shouldSelectNextLetter = false;
 		}
 
 		return true;
@@ -51,6 +51,14 @@ public class ModeABC extends InputMode {
 		return newTextCase == CASE_UPPER ? word.toUpperCase(language.getLocale()) : word.toLowerCase(language.getLocale());
 	}
 
+	private void refreshSuggestions() {
+		if (digitSequence.isEmpty()) {
+			suggestions.clear();
+		} else {
+			onNumber(digitSequence.charAt(0) - '0', false, 0);
+		}
+	}
+
 	@Override
 	protected boolean nextSpecialCharacters() {
 		if (digitSequence.equals(Language.SPECIAL_CHARS_KEY) && super.nextSpecialCharacters()) {
@@ -70,6 +78,9 @@ public class ModeABC extends InputMode {
 		if (language.hasUpperCase()) {
 			allowedTextCases.add(CASE_UPPER);
 		}
+
+		refreshSuggestions();
+		shouldSelectNextLetter = true; // do not accept any previous suggestions after loading the new ones
 	}
 
 	@Override public int getSequenceLength() { return 1; }

app/src/main/java/io/github/sspanak/tt9/languages/Language.java

@@ -266,6 +266,29 @@ public class Language implements Comparable<Language> {
 	}
 
 
+	/**
+	 * Checks whether the given word contains characters outside of the language alphabet.
+	 */
+	public boolean isValidWord(String word) {
+		if (word == null || word.isEmpty() || (word.length() == 1 && Character.isDigit(word.charAt(0)))) {
+			return true;
+		}
+
+		String lowerCaseWord = word.toLowerCase(locale);
+		if (characterKeyMap.isEmpty()) {
+			generateCharacterKeyMap();
+		}
+
+		for (int i = 0; i < lowerCaseWord.length(); i++) {
+			if (!characterKeyMap.containsKey(lowerCaseWord.charAt(i))) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+
 	@NonNull
 	@Override
 	public String toString() {

app/src/main/java/io/github/sspanak/tt9/ui/UI.java

@@ -7,10 +7,15 @@ import android.os.Looper;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
+
 import io.github.sspanak.tt9.ime.TraditionalT9;
+import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.preferences.PreferencesActivity;
 
 public class UI {
+	private static Toast toastLang = null;
+
 	public static void showAddWordDialog(TraditionalT9 tt9, int language, String currentWord) {
 		Intent intent = new Intent(tt9, PopupDialogActivity.class);
 		intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
@@ -93,4 +98,15 @@ public class UI {
 	public static void toastLong(Context context, CharSequence msg) {
 		Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
 	}
+
+	public static void toastLanguage(@NonNull Context context, @NonNull Language language) {
+		if (toastLang != null) {
+			toastLang.cancel();
+		}
+
+		// we recreate the toast, because if set new text, when it is fading out,
+		// the new text is discarded
+		toastLang = Toast.makeText(context, language.getName(), Toast.LENGTH_SHORT);
+		toastLang.show();
+	}
 }