added support for other than '#' chars

build.gradle

@@ -3,9 +3,14 @@
 buildscript {
     repositories {
         jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
+        google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:1.5.0'
+        classpath 'com.android.tools.build:gradle:3.6.1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -15,6 +20,10 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
 }
 

gradle.properties

@@ -15,4 +15,6 @@
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
-# org.gradle.parallel=true
+# org.gradle.parallel=true
+android.useAndroidX=true
+android.enableJetifier=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Wed Oct 21 11:34:03 PDT 2015
+#Mon Mar 02 16:51:36 CET 2020
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.8-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip

hashtag-helper/build.gradle

@@ -1,12 +1,12 @@
 apply plugin: 'com.android.library'
 
 android {
-    compileSdkVersion 23
-    buildToolsVersion "21.1.2"
+    compileSdkVersion 29
+    buildToolsVersion "29.0.2"
 
     defaultConfig {
         minSdkVersion 15
-        targetSdkVersion 23
+        targetSdkVersion 29
         versionCode 1
         versionName "1.1"
     }
@@ -19,7 +19,7 @@ android {
 }
 
 dependencies {
-    compile fileTree(dir: 'libs', include: ['*.jar'])
-    testCompile 'junit:junit:4.12'
-    compile 'com.android.support:appcompat-v7:23.1.1'
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    testImplementation 'junit:junit:4.12'
+    implementation 'androidx.appcompat:appcompat:1.1.0'
 }

hashtag-helper/src/main/java/com/volokh/danylo/hashtaghelper/ClickableForegroundColorSpan.java

@@ -1,6 +1,7 @@
 package com.volokh.danylo.hashtaghelper;
 
-import android.support.annotation.ColorInt;
+import androidx.annotation.ColorInt;
+
 import android.text.Spanned;
 import android.text.TextPaint;
 import android.text.style.ClickableSpan;
@@ -11,15 +12,19 @@
  * Created by danylo.volokh on 12/22/2015.
  * This class is a combination of {@link android.text.style.ForegroundColorSpan}
  * and {@link ClickableSpan}.
- *
+ * <p>
  * You can set a color of this span plus set a click listener
  */
 public class ClickableForegroundColorSpan extends ClickableSpan {
 
     private OnHashTagClickListener mOnHashTagClickListener;
 
     public interface OnHashTagClickListener {
-        void onHashTagClicked(String hashTag);
+        /**
+         * @param initialChar is a {@link Character} which helps to determine click event
+         * @param hashTag     simple {@link String} after initialChar
+         */
+        void onHashTagClicked(Character initialChar, String hashTag);
     }
 
     private final int mColor;
@@ -46,6 +51,10 @@ public void onClick(View widget) {
         int start = s.getSpanStart(this);
         int end = s.getSpanEnd(this);
 
-        mOnHashTagClickListener.onHashTagClicked(text.subSequence(start + 1/*skip "#" sign*/, end).toString());
+        mOnHashTagClickListener
+                .onHashTagClicked(
+                        text.charAt(start),
+                        text.subSequence(start + 1/*skip "#" sign*/, end).toString()
+                );
     }
 }

hashtag-helper/src/main/java/com/volokh/danylo/hashtaghelper/HashTagHelper.java

@@ -9,6 +9,9 @@
 import android.text.style.ForegroundColorSpan;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -17,46 +20,85 @@
 /**
  * This is a helper class that should be used with {@link android.widget.EditText} or {@link android.widget.TextView}
  * In order to have hash-tagged words highlighted. It also provides a click listeners for every hashtag
- *
+ * <p>
  * Example :
  * #ThisIsHashTagWord
  * #ThisIsFirst#ThisIsSecondHashTag
  * #hashtagendsifitfindsnotletterornotdigitsignlike_thisIsNotHighlithedArea
- *
  */
 public final class HashTagHelper implements ClickableForegroundColorSpan.OnHashTagClickListener {
 
+    private static final Character NEW_LINE = '\n';
+    private static final Character CARRIAGE_RETURN = '\r';
+    private static final Character SPACE = ' ';
+
     /**
      * If this is not null then  all of the symbols in the List will be considered as valid symbols of hashtag
      * For example :
      * mAdditionalHashTagChars = {'$','_','-'}
      * it means that hashtag: "#this_is_hashtag-with$dollar-sign" will be highlighted.
-     *
+     * <p>
      * Note: if mAdditionalHashTagChars would be "null" only "#this" would be highlighted
-     *
      */
     private final List<Character> mAdditionalHashTagChars;
+
+    /**
+     * If this is not null then all of the symbols in the List will be considered as valid start symbols
+     * For example:
+     * mStartChars = {'@','%'}
+     * it means that all words starting with these symbols will be highlighted.
+     * <p>
+     * Note: if mStartChars is null, words started with '#' symbol will be highlighted
+     */
+    private final List<Character> mStartChars;
     private TextView mTextView;
     private int mHashTagWordColor;
 
+    /**
+     * Character style needs to separate different spans in the text
+     */
+    private Class<? extends CharacterStyle> mCharacterStyle;
+
     private OnHashTagClickListener mOnHashTagClickListener;
 
-    public static final class Creator{
+    private final ArrayList<Character> mForbiddenCharacters = new ArrayList<>();
+
+    public static final class Creator {
+
+        private Creator() {
+        }
 
-        private Creator(){}
+        public static HashTagHelper create(int color, OnHashTagClickListener listener) {
+            return new HashTagHelper(color, listener, null, null, null);
+        }
 
-        public static HashTagHelper create(int color, OnHashTagClickListener listener){
-            return new HashTagHelper(color, listener, null);
+        public static HashTagHelper create(int color, OnHashTagClickListener listener, @NonNull List<Character> additionalHashTagChars) {
+            return new HashTagHelper(color, listener, additionalHashTagChars, null, null);
         }
 
-        public static HashTagHelper create(int color, OnHashTagClickListener listener, char... additionalHashTagChars){
-            return new HashTagHelper(color, listener, additionalHashTagChars);
+        public static HashTagHelper create(
+                int color,
+                OnHashTagClickListener listener,
+                List<Character> additionalHashTagChars,
+                @NonNull List<Character> startChars
+        ) {
+            return new HashTagHelper(color, listener, additionalHashTagChars, startChars, null);
+        }
+
+        public static HashTagHelper create(
+                int color,
+                OnHashTagClickListener listener,
+                List<Character> additionalHashTagChars,
+                List<Character> startChars,
+                @NonNull Class<? extends ClickableForegroundColorSpan> characterStyle
+        ) {
+            return new HashTagHelper(color, listener, additionalHashTagChars, startChars, characterStyle);
         }
 
     }
 
-    public interface OnHashTagClickListener{
-        void onHashTagClicked(String hashTag);
+    public interface OnHashTagClickListener {
+        void onHashTagClicked(Character initialChar, String hashTag);
     }
 
     private final TextWatcher mTextWatcher = new TextWatcher() {
@@ -76,27 +118,50 @@ public void afterTextChanged(Editable s) {
         }
     };
 
-    private HashTagHelper(int color, OnHashTagClickListener listener, char... additionalHashTagCharacters) {
+    private HashTagHelper(
+            int color,
+            OnHashTagClickListener listener,
+            @Nullable List<Character> additionalHashTagChars,
+            @Nullable List<Character> startChars,
+            @Nullable Class<? extends ClickableForegroundColorSpan> characterStyle
+    ) {
+
+        addForbiddenCharactersToList();
+
+        if (characterStyle == null) {
+            mCharacterStyle = ClickableForegroundColorSpan.class;
+        } else {
+            mCharacterStyle = characterStyle;
+        }
         mHashTagWordColor = color;
         mOnHashTagClickListener = listener;
         mAdditionalHashTagChars = new ArrayList<>();
+        mStartChars = new ArrayList<>();
 
-        if(additionalHashTagCharacters != null){
-            for(char additionalChar : additionalHashTagCharacters){
-                mAdditionalHashTagChars.add(additionalChar);
-            }
+        if (additionalHashTagChars != null) {
+            mAdditionalHashTagChars.addAll(additionalHashTagChars);
         }
+
+        if (startChars != null) {
+            mStartChars.addAll(startChars);
+        }
+    }
+
+    private void addForbiddenCharactersToList() {
+        mForbiddenCharacters.add(NEW_LINE);
+        mForbiddenCharacters.add(SPACE);
+        mForbiddenCharacters.add(CARRIAGE_RETURN);
     }
 
-    public void handle(TextView textView){
-        if(mTextView == null){
+    public void handle(TextView textView) {
+        if (mTextView == null) {
             mTextView = textView;
             mTextView.addTextChangedListener(mTextWatcher);
 
             // in order to use spannable we have to set buffer type
             mTextView.setText(mTextView.getText(), TextView.BufferType.SPANNABLE);
 
-            if(mOnHashTagClickListener != null){
+            if (mOnHashTagClickListener != null) {
                 // we need to set this in order to get onClick event
                 mTextView.setMovementMethod(LinkMovementMethod.getInstance());
 
@@ -117,7 +182,7 @@ private void eraseAndColorizeAllText(CharSequence text) {
 
         Spannable spannable = ((Spannable) mTextView.getText());
 
-        CharacterStyle[] spans = spannable.getSpans(0, text.length(), CharacterStyle.class);
+        CharacterStyle[] spans = spannable.getSpans(0, text.length(), mCharacterStyle);
         for (CharacterStyle span : spans) {
             spannable.removeSpan(span);
         }
@@ -126,17 +191,18 @@ private void eraseAndColorizeAllText(CharSequence text) {
     }
 
     private void setColorsToAllHashTags(CharSequence text) {
-
+        String trimmedText = text.toString().trim();
         int startIndexOfNextHashSign;
 
         int index = 0;
-        while (index < text.length()-  1){
-            char sign = text.charAt(index);
+        while (index < trimmedText.length() - 1) {
+            char sign = trimmedText.charAt(index);
+            char nextSign = trimmedText.charAt(index + 1);
             int nextNotLetterDigitCharIndex = index + 1; // we assume it is next. if if was not changed by findNextValidHashTagChar then index will be incremented by 1
-            if(sign == '#'){
+            if (mStartChars.contains(sign) && !mStartChars.contains(nextSign) && !mForbiddenCharacters.contains(nextSign)) {
                 startIndexOfNextHashSign = index;
 
-                nextNotLetterDigitCharIndex = findNextValidHashTagChar(text, startIndexOfNextHashSign);
+                nextNotLetterDigitCharIndex = findNextValidHashTagChar(trimmedText, startIndexOfNextHashSign);
 
                 setColorForHashTagToTheEnd(startIndexOfNextHashSign, nextNotLetterDigitCharIndex);
             }
@@ -152,7 +218,8 @@ private int findNextValidHashTagChar(CharSequence text, int start) {
 
             char sign = text.charAt(index);
 
-            boolean isValidSign = Character.isLetterOrDigit(sign) || mAdditionalHashTagChars.contains(sign);
+            boolean isValidSign = (Character.isLetterOrDigit(sign) || mAdditionalHashTagChars.contains(sign))
+                    && !mStartChars.contains(sign);
             if (!isValidSign) {
                 nonLetterDigitCharIndex = index;
                 break;
@@ -171,7 +238,7 @@ private void setColorForHashTagToTheEnd(int startIndex, int nextNotLetterDigitCh
 
         CharacterStyle span;
 
-        if(mOnHashTagClickListener != null){
+        if (mOnHashTagClickListener != null) {
             span = new ClickableForegroundColorSpan(mHashTagWordColor, this);
         } else {
             // no need for clickable span because it is messing with selection when click
@@ -189,11 +256,11 @@ public List<String> getAllHashTags(boolean withHashes) {
         // use set to exclude duplicates
         Set<String> hashTags = new LinkedHashSet<>();
 
-        for (CharacterStyle span : spannable.getSpans(0, text.length(), CharacterStyle.class)) {
+        for (CharacterStyle span : spannable.getSpans(0, text.length(), mCharacterStyle)) {
             hashTags.add(
                     text.substring(!withHashes ? spannable.getSpanStart(span) + 1/*skip "#" sign*/
-                                           : spannable.getSpanStart(span),
-                                   spannable.getSpanEnd(span)));
+                                    : spannable.getSpanStart(span),
+                            spannable.getSpanEnd(span)));
         }
 
         return new ArrayList<>(hashTags);
@@ -204,7 +271,7 @@ public List<String> getAllHashTags() {
     }
 
     @Override
-    public void onHashTagClicked(String hashTag) {
-        mOnHashTagClickListener.onHashTagClicked(hashTag);
+    public void onHashTagClicked(Character initialChar, String hashTag) {
+        mOnHashTagClickListener.onHashTagClicked(initialChar, hashTag);
     }
 }

sample_app/build.gradle

@@ -1,13 +1,13 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 23
-    buildToolsVersion "21.1.2"
+    compileSdkVersion 29
+    buildToolsVersion "29.0.2"
 
     defaultConfig {
         applicationId "com.volokh.danylo.hashtaghelper"
         minSdkVersion 15
-        targetSdkVersion 23
+        targetSdkVersion 29
         versionCode 1
         versionName "1.0"
     }
@@ -20,8 +20,8 @@ android {
 }
 
 dependencies {
-    compile fileTree(dir: 'libs', include: ['*.jar'])
-    testCompile 'junit:junit:4.12'
-    compile 'com.android.support:appcompat-v7:23.1.1'
-    compile project(':hashtag-helper')
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    testImplementation 'junit:junit:4.12'
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+    implementation project(':hashtag-helper')
 }