StringHelper is a utility class using a similar interface and proposing similar functionalities than commons lang StringUtils. Internally it is using Android system methods.

StringHelper.java

package X.Y.Z;

import android.text.TextUtils;
import android.util.Base64;

 /**
 * Created by ylemin on 07/09/15.
 *
 * This class is similar in functionalities as the commons.lang.StringUtils, but using as much
 * of the Android built-in tools and helpers as possible
 */
public class StringHelper {

    /**
     * Constructors
     */

    private StringHelper() {
        // should not be instantiated
    }

    /**
     * Public Methods
     */

    public static boolean isNotBlank(CharSequence value) {
        return !TextUtils.isEmpty(value);
    }

    public static boolean isBlank(CharSequence value) {
        return TextUtils.isEmpty(value);
    }

    public static boolean isAnyBlank(CharSequence... values) {
        for (int i = 0, count = values.length; i < count; i++) {
            CharSequence value = values[i];
            if (isBlank(value)) {
                return true;
            }
        }
        return false;
    }

    public static boolean isNoneBlank(CharSequence... values) {
        for (int i = 0, count = values.length; i < count; i++) {
            CharSequence value = values[i];
            if (isBlank(value)) {
                return false;
            }
        }

        return true;
    }

    public static boolean containsAnyToken(String input, String tokens, String tokenDelimiter) {
        if (isAnyBlank(input, tokens)) {
            return false;
        }

        if (isBlank(tokenDelimiter)) {
            return input.contains(tokens);
        } else {
            String[] splitTokens = tokens.split(tokenDelimiter);
            for (int i = 0, count = splitTokens.length; i < count; i++) {
                if (input.contains(splitTokens[i])) {
                    return true;
                }
            }
            return false;
        }
    }

    public static int countOccurences(String input, char character) {
        int counter = 0;
        for (int i = 0; i < input.length(); i++) {
            if (input.charAt(i) == character) {
                counter++;
            }
        }
        return counter;
    }

    public static String toBase64(String input) {
        return Base64.encodeToString(input.getBytes(), Base64.DEFAULT);
    }
}