quote empty whitespaces for xml encoding

src/main/java/com/reandroid/apk/xmldecoder/XMLDecodeHelper.java

@@ -29,7 +29,10 @@ public class XMLDecodeHelper {
             return;
         }
         if(!stringItem.hasStyle()){
-            writer.text(ValueDecoder.escapeSpecialCharacter(stringItem.get()));
+            String text = stringItem.get();
+            text = ValueDecoder.escapeSpecialCharacter(text);
+            text = ValueDecoder.quoteWhitespace(text);
+            writer.text(text);
         }else {
             String xml = stringItem.getXml();
             XMLElement element = parseSpanSafe(xml);

src/main/java/com/reandroid/apk/xmlencoder/ValuesStringPoolBuilder.java

@@ -1,4 +1,4 @@
- /*
+/*
   *  Copyright (C) 2022 github.com/REAndroid
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
@@ -158,7 +158,9 @@ import java.util.*;
             addStyleElement(element);
         }else {
             String text = ValueDecoder
-                    .unEscapeSpecialCharacter(element.getTextContent());
+                    .unQuoteWhitespace(element.getTextContent());
+            text = ValueDecoder
+                    .unEscapeSpecialCharacter(text);
             addString(text);
         }
     }

src/main/java/com/reandroid/apk/xmlencoder/XMLValuesEncoderString.java

@@ -25,7 +25,6 @@ class XMLValuesEncoderString extends XMLValuesEncoder{
         super(materials);
     }
 
-
     @Override
     void encodeValue(Entry entry, XMLElement element){
         if(!element.hasChildElements()){
@@ -36,7 +35,9 @@ class XMLValuesEncoderString extends XMLValuesEncoder{
     }
     @Override
     void encodeStringValue(Entry entry, String value){
-        entry.setValueAsString(ValueDecoder.unEscapeSpecialCharacter(value));
+        value = ValueDecoder.unQuoteWhitespace(value);
+        value = ValueDecoder.unEscapeSpecialCharacter(value);
+        entry.setValueAsString(value);
     }
     @Override
     void encodeNullValue(Entry entry){

src/main/java/com/reandroid/arsc/decoder/ValueDecoder.java

@@ -50,6 +50,48 @@ public class ValueDecoder {
         }
         return text.substring(1);
     }
+    public static String quoteWhitespace(String text){
+        if(!isWhiteSpace(text)){
+            return text;
+        }
+        return "\"" + text + "\"";
+    }
+    public static String unQuoteWhitespace(String text){
+        if(text == null || text.length() < 3){
+            return text;
+        }
+        if(text.charAt(0) != '"' || text.charAt(text.length()-1) != '"'){
+            return text;
+        }
+        String unQuoted = text.substring(1, text.length()-1);
+        if(!isWhiteSpace(unQuoted)){
+            return text;
+        }
+        return unQuoted;
+    }
+    private static boolean isWhiteSpace(String text){
+        if(text == null || text.length() == 0){
+            return false;
+        }
+        char[] chars = text.toCharArray();
+        for(int i = 0; i < chars.length; i++){
+            if(!isWhiteSpace(chars[i])){
+                return false;
+            }
+        }
+        return true;
+    }
+    private static boolean isWhiteSpace(char ch){
+        switch (ch){
+            case ' ':
+            case '\n':
+            case '\r':
+            case '\t':
+                return true;
+            default:
+                return false;
+        }
+    }
     private static boolean isSpecialCharacter(char ch){
         switch (ch){
             case '@':