Android helper functions for highlighting a search term in a given CharSequence.

CharSequences.java

import android.support.annotation.ColorInt;
import android.text.SpannableStringBuilder;
import android.text.style.ForegroundColorSpan;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.jetbrains.annotations.NotNull;

import static android.text.Spanned.SPAN_INCLUSIVE_EXCLUSIVE;

public class CharSequences {

  @NotNull public static final Pattern SPACE = Pattern.compile("\\s");

  private CharSequences() {
    // no instances
  }

  /**
   * Highlights the search term in the given color throughout the given text. If the search term
   * consists of multiple words, each word is searched for and highlighted separately.
   *
   * @param searchTerm search term to highlight
   * @param text text in which to highlight the search term
   * @param colorInt highlight color
   * @return the resulting text with highlights
   */
  public static CharSequence highlightSearchTermInText(CharSequence searchTerm, CharSequence text, @ColorInt int colorInt) {
    return highlightSearchTermInText(SPACE.split(searchTerm), text, colorInt);
  }

  @SuppressWarnings("ForLoopReplaceableByForEach")
  public static CharSequence highlightSearchTermInText(CharSequence[] searchWords, CharSequence text, @ColorInt
      int colorInt) {
    final SpannableStringBuilder highlighted = new SpannableStringBuilder(text);
    for (int i = 0; i < searchWords.length; i++) {
      final CharSequence word = searchWords[i];
      highlightSearchTermInText(word, highlighted, colorInt);
    }

    return highlighted;
  }

  public static SpannableStringBuilder highlightSearchTermInText(CharSequence searchWord, SpannableStringBuilder stringBuilder, @ColorInt int colorInt) {

    if (searchWord.length() == 0) return stringBuilder;

    final Pattern searchPattern = Pattern.compile(searchWord.toString(), Pattern.CASE_INSENSITIVE);
    final Matcher matcher = searchPattern.matcher(stringBuilder);
    while (matcher.find()) {
      stringBuilder.setSpan(new ForegroundColorSpan(colorInt), matcher.start(0), matcher.end(0), SPAN_INCLUSIVE_EXCLUSIVE);
    }

    //Timber.d("spannableStringBuilder = %s", stringBuilder);
    return stringBuilder;
  }
}