TextUtils: fixup isEmpty() and add equals()

src/api-impl/android/text/TextUtils.java

@@ -62,6 +62,30 @@ public class TextUtils {
 	}
 
 	public static boolean isEmpty(CharSequence str) {
-		return str.equals(""); // presumably?
+		return str == null || str.equals("");
 	}
+
+	/**
+     * Returns true if a and b are equal, including if they are both null.
+     * <p><i>Note: In platform versions 1.1 and earlier, this method only worked well if
+     * both the arguments were instances of String.</i></p>
+     * @param a first CharSequence to check
+     * @param b second CharSequence to check
+     * @return true if a and b are equal
+     */
+    public static boolean equals(CharSequence a, CharSequence b) {
+        if (a == b) return true;
+        int length;
+        if (a != null && b != null && (length = a.length()) == b.length()) {
+            if (a instanceof String && b instanceof String) {
+                return a.equals(b);
+            } else {
+                for (int i = 0; i < length; i++) {
+                    if (a.charAt(i) != b.charAt(i)) return false;
+                }
+                return true;
+            }
+        }
+        return false;
+    }
 }