cleanup for r1812476: avoid NPEs from string.isEmpty()

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1812516 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 12 insertions, 1 deletions

diff --git a/src/java/org/apache/poi/poifs/crypt/CryptoFunctions.java b/src/java/org/apache/poi/poifs/crypt/CryptoFunctions.java
index 9273f53e0e..6a16e3f9dc 100644
--- a/src/java/org/apache/poi/poifs/crypt/CryptoFunctions.java
+++ b/src/java/org/apache/poi/poifs/crypt/CryptoFunctions.java
@@ -374,6 +374,10 @@ public class CryptoFunctions {
      * @return the verifier (actually a short value)
      */
     public static int createXorVerifier1(String password) {
+        if (password == null) {
+            throw new IllegalArgumentException("Password cannot be null");
+        }
+
         byte[] arrByteChars = toAnsiPassword(password);
         
         // SET Verifier TO 0x0000
@@ -412,6 +416,10 @@ public class CryptoFunctions {
      * @see <a href="http://www.aspose.com/blogs/aspose-blogs/vladimir-averkin/archive/2007/08/20/funny-how-the-new-powerful-cryptography-implemented-in-word-2007-turns-it-into-a-perfect-tool-for-document-password-removal.html">Funny: How the new powerful cryptography implemented in Word 2007 turns it into a perfect tool for document password removal.</a>
      */
     public static int createXorVerifier2(String password) {
+        if (password == null) {
+            throw new IllegalArgumentException("Password cannot be null");
+        }
+
         //Array to hold Key Values
         byte[] generatedKey = new byte[4];
 
diff --git a/src/java/org/apache/poi/ss/formula/eval/StringEval.java b/src/java/org/apache/poi/ss/formula/eval/StringEval.java
index 0e35e9dea4..61515e438f 100644
--- a/src/java/org/apache/poi/ss/formula/eval/StringEval.java
+++ b/src/java/org/apache/poi/ss/formula/eval/StringEval.java
@@ -17,6 +17,8 @@
 
 package org.apache.poi.ss.formula.eval;
 
+//import org.checkerframework.checker.nullness.qual.NonNull;
+
 import org.apache.poi.ss.formula.ptg.Ptg;
 import org.apache.poi.ss.formula.ptg.StringPtg;
 
@@ -27,6 +29,7 @@ public final class StringEval implements StringValueEval {
 
 	public static final StringEval EMPTY_INSTANCE = new StringEval("");
 
+	//@NotNull
 	private final String _value;
 
 	public StringEval(Ptg ptg) {
diff --git a/src/java/org/apache/poi/ss/usermodel/FractionFormat.java b/src/java/org/apache/poi/ss/usermodel/FractionFormat.java
index 76834a7ed8..d90d50068b 100644
--- a/src/java/org/apache/poi/ss/usermodel/FractionFormat.java
+++ b/src/java/org/apache/poi/ss/usermodel/FractionFormat.java
@@ -150,7 +150,7 @@ public class FractionFormat extends Format {
         }
         
         //if whole part has to go into the numerator
-        if (wholePartFormatString.isEmpty()){
+        if (wholePartFormatString == null || wholePartFormatString.isEmpty()){
             int trueNum = (fract.getDenominator()*(int)wholePart)+fract.getNumerator();
             sb.append(trueNum).append("/").append(fract.getDenominator());
             return sb.toString();