VoiceVariant.java: Use MALE and FEMALE string constants.

android/src/com/reecedunn/espeak/TtsService.java

         if (variantString == null) {
             final int gender = getPreferenceValue(prefs, "default_gender", SpeechSynthesis.GENDER_MALE);
             if (gender == SpeechSynthesis.GENDER_FEMALE) {
-                variant = VoiceVariant.parseVoiceVariant("female");
+                variant = VoiceVariant.parseVoiceVariant(VoiceVariant.FEMALE);
             } else {
-                variant = VoiceVariant.parseVoiceVariant("male");
+                variant = VoiceVariant.parseVoiceVariant(VoiceVariant.MALE);
             }
         } else {
             variant = VoiceVariant.parseVoiceVariant(variantString);

android/src/com/reecedunn/espeak/TtsSettingsActivity.java

         if (variant == null) {
             String gender = prefs.getString("default_gender", "0");
             if (gender.equals("2")) {
-                editor.putString("espeak_variant", "female");
+                editor.putString("espeak_variant", VoiceVariant.FEMALE);
             } else {
-                editor.putString("espeak_variant", "male");
+                editor.putString("espeak_variant", VoiceVariant.MALE);
             }
         }
 

android/src/com/reecedunn/espeak/VoiceVariant.java

 public class VoiceVariant {
     private static final Pattern mVariantPattern = Pattern.compile("-");
 
+    public static final String MALE = "male";
+    public static final String FEMALE = "female";
+
     public final String variant;
     public final int gender;
     public final int age;
 
     protected VoiceVariant(String variant, int age) {
-        if (variant.equals("male")) {
+        if (variant.equals(MALE)) {
             this.variant = null;
             this.gender = SpeechSynthesis.GENDER_MALE;
-        } else if (variant.equals("female")) {
+        } else if (variant.equals(FEMALE)) {
             this.variant = null;
             this.gender = SpeechSynthesis.GENDER_FEMALE;
         } else {
     public String toString() {
         final String ret;
         if (gender == SpeechSynthesis.GENDER_MALE) {
-            ret = "male";
+            ret = MALE;
         } else if (gender == SpeechSynthesis.GENDER_FEMALE) {
-            ret = "female";
+            ret = FEMALE;
         } else {
             ret = variant;
         }