CHAR_SEQUENCE_CREATOR cannot handle null string

TextUtils.writeToParcel can handle null as input CharSequence
but createFromParcel will throw NullPointerException. Transforming
to and from parcel should handle null in the same way.

Change-Id: I707ea9be2091d2655c5f63eaa57c5674befa5ad3

Author: Martin Wallgren

core/java/android/text/TextUtils.java

@@ -627,10 +627,16 @@ private static void writeWhere(Parcel p, Spanned sp, Object o) {
         public  CharSequence createFromParcel(Parcel p) {
             int kind = p.readInt();
 
-            if (kind == 1)
-                return p.readString();
+            String string = p.readString();
+            if (string == null) {
+                return null;
+            }
+
+            if (kind == 1) {
+                return string;
+            }
 
-            SpannableString sp = new SpannableString(p.readString());
+            SpannableString sp = new SpannableString(string);
 
             while (true) {
                 kind = p.readInt();

core/tests/coretests/src/android/text/TextUtilsTest.java

@@ -17,6 +17,7 @@
 package android.text;
 
 import android.graphics.Paint;
+import android.os.Parcel;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.test.suitebuilder.annotation.SmallTest;
 import android.text.Spannable;
@@ -352,6 +353,51 @@ public void testDelimitedStringContains() {
         assertFalse(TextUtils.delimitedStringContains("network,mock,gpsx", ',', "gps"));
     }
 
+    @SmallTest
+    public void testCharSequenceCreator() {
+        Parcel p = Parcel.obtain();
+        TextUtils.writeToParcel(null, p, 0);
+        CharSequence text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p);
+        assertNull("null CharSequence should generate null from parcel", text);
+        p = Parcel.obtain();
+        TextUtils.writeToParcel("test", p, 0);
+        text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p);
+        assertEquals("conversion to/from parcel failed", "test", text);
+    }
+
+    @SmallTest
+    public void testCharSequenceCreatorNull() {
+        Parcel p;
+        CharSequence text;
+        p = Parcel.obtain();
+        TextUtils.writeToParcel(null, p, 0);
+        p.setDataPosition(0);
+        text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p);
+        assertNull("null CharSequence should generate null from parcel", text);
+    }
+
+    @SmallTest
+    public void testCharSequenceCreatorSpannable() {
+        Parcel p;
+        CharSequence text;
+        p = Parcel.obtain();
+        TextUtils.writeToParcel(new SpannableString("test"), p, 0);
+        p.setDataPosition(0);
+        text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p);
+        assertEquals("conversion to/from parcel failed", "test", text.toString());
+    }
+
+    @SmallTest
+    public void testCharSequenceCreatorString() {
+        Parcel p;
+        CharSequence text;
+        p = Parcel.obtain();
+        TextUtils.writeToParcel("test", p, 0);
+        p.setDataPosition(0);
+        text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p);
+        assertEquals("conversion to/from parcel failed", "test", text.toString());
+    }
+
     /**
      * CharSequence wrapper for testing the cases where text is copied into
      * a char array instead of working from a String or a Spanned.