Predictive Mode: when there is no dictionary for the current language, a toast message will appear asking the user to load it from Settings

src/io/github/sspanak/tt9/db/DictionaryDb.java

@@ -70,6 +70,17 @@ public class DictionaryDb {
 	}
 
 
+	public static void areThereWords(Handler handler, Language language) {
+		new Thread() {
+			@Override
+			public void run() {
+				int langId = language != null ? language.getId() : -1;
+				handler.sendEmptyMessage(getInstance().wordsDao().count(langId) > 0 ? 1 : 0);
+			}
+		}.start();
+	}
+
+
 	public static void truncateWords(Handler handler) {
 		new Thread() {
 			@Override

src/io/github/sspanak/tt9/db/WordsDao.java

@@ -9,6 +9,9 @@ import java.util.List;
 
 @Dao
 interface WordsDao {
+	@Query("SELECT COUNT(id) FROM words WHERE :langId < 0 OR lang = :langId")
+	int count(int langId);
+
 	@Query(
 		"SELECT * " +
 		"FROM words " +

src/io/github/sspanak/tt9/ime/EmptyDatabaseWarning.java

@@ -0,0 +1,67 @@
+package io.github.sspanak.tt9.ime;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+
+import java.util.HashMap;
+
+import io.github.sspanak.tt9.R;
+import io.github.sspanak.tt9.db.DictionaryDb;
+import io.github.sspanak.tt9.languages.Language;
+import io.github.sspanak.tt9.languages.LanguageCollection;
+import io.github.sspanak.tt9.preferences.SettingsStore;
+import io.github.sspanak.tt9.ui.UI;
+
+public class EmptyDatabaseWarning {
+	final int WARNING_INTERVAL;
+	private static final HashMap<Integer, Long> warningDisplayedTime = new HashMap<>();
+
+	private Language language;
+
+	public EmptyDatabaseWarning(SettingsStore settings) {
+		WARNING_INTERVAL = settings.getDictionaryMissingWarningInterval();
+
+		for (Language lang : LanguageCollection.getAll()) {
+			if (!warningDisplayedTime.containsKey(lang.getId())) {
+				warningDisplayedTime.put(lang.getId(), 0L);
+			}
+		}
+	}
+
+	public void emitOnce(Language language) {
+		if (language == null) {
+			return;
+		}
+
+		this.language = language;
+		DictionaryDb.areThereWords(handleWordCount, language);
+	}
+
+	private final Handler handleWordCount = new Handler(Looper.getMainLooper()) {
+		@Override
+		public void handleMessage(Message msg) {
+			boolean areThereWords = msg.what == 1;
+
+			if (areThereWords) {
+				return;
+			}
+
+			Context context = TraditionalT9.getMainContext();
+			if (context == null || !warningDisplayedTime.containsKey(language.getId())) {
+				return;
+			}
+
+			long now = System.currentTimeMillis();
+			Long lastWarningTime = warningDisplayedTime.get(language.getId());
+			boolean isItWarningTimeAgain = lastWarningTime != null && now - lastWarningTime > WARNING_INTERVAL;
+
+			if (isItWarningTimeAgain) {
+				String message = context.getString(R.string.dictionary_missing_go_load_it, language.getName());
+				UI.toastLong(context, message);
+				warningDisplayedTime.put(language.getId(), now);
+			}
+		}
+	};
+}

src/io/github/sspanak/tt9/ime/modes/ModePredictive.java

@@ -10,12 +10,14 @@ import java.util.regex.Pattern;
 
 import io.github.sspanak.tt9.Logger;
 import io.github.sspanak.tt9.db.DictionaryDb;
+import io.github.sspanak.tt9.ime.EmptyDatabaseWarning;
 import io.github.sspanak.tt9.ime.InputFieldHelper;
 import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.languages.Punctuation;
 import io.github.sspanak.tt9.preferences.SettingsStore;
 
 public class ModePredictive extends InputMode {
+	private final EmptyDatabaseWarning emptyDbWarning;
 	private final SettingsStore settings;
 
 	public int getId() { return MODE_PREDICTIVE; }
@@ -42,11 +44,13 @@ public class ModePredictive extends InputMode {
 
 
 	ModePredictive(SettingsStore settings) {
-		this.settings = settings;
 		allowedTextCases.add(CASE_LOWER);
 		allowedTextCases.add(CASE_CAPITALIZE);
 		allowedTextCases.add(CASE_UPPER);
 
+		emptyDbWarning = new EmptyDatabaseWarning(settings);
+		this.settings = settings;
+
 		// digitSequence limiter when selecting emoji
 		// "11" = Emoji level 0, "111" = Emoji level 1,... up to the maximum amount of 1s
 		StringBuilder maxEmojiSequenceBuilder = new StringBuilder();
@@ -344,6 +348,7 @@ public class ModePredictive extends InputMode {
 			dbSuggestions = dbSuggestions == null ? new ArrayList<>() : dbSuggestions;
 
 			if (dbSuggestions.size() == 0 && digitSequence.length() > 0) {
+				emptyDbWarning.emitOnce(currentLanguage);
 				dbSuggestions = generatePossibleCompletions(currentLanguage, currentInputFieldWord);
 			}
 

src/io/github/sspanak/tt9/preferences/SettingsStore.java

@@ -209,6 +209,8 @@ public class SettingsStore {
 	public int getDictionaryImportProgressUpdateInterval() { return 250; /* ms */ }
 	public int getDictionaryImportWordChunkSize() { return 1000; /* words */ }
 
+	public int getDictionaryMissingWarningInterval() { return 30000; /* ms */ }
+
 	public int getSuggestionsMax() { return 20; }
 	public int getSuggestionsMin() { return 8; }