Do not throw NPE for equals(null) (#8910)

Change-Id: Ie9a658911c9f2722e518dedbe181c24e5ace07db

server/src/com/vaadin/data/util/filter/Between.java

@@ -67,6 +67,10 @@ public class Between implements Filter {
 
     @Override
     public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+
         // Only objects of the same class can be equal
         if (!getClass().equals(obj.getClass())) {
             return false;

server/src/com/vaadin/data/util/filter/Compare.java

@@ -307,6 +307,9 @@ public abstract class Compare implements Filter {
 
     @Override
     public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
 
         // Only objects of the same class can be equal
         if (!getClass().equals(obj.getClass())) {

server/src/com/vaadin/data/util/filter/IsNull.java

@@ -62,6 +62,10 @@ public final class IsNull implements Filter {
 
     @Override
     public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+
         // Only objects of the same class can be equal
         if (!getClass().equals(obj.getClass())) {
             return false;

server/src/com/vaadin/data/util/filter/Like.java

@@ -84,6 +84,10 @@ public class Like implements Filter {
 
     @Override
     public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+
         // Only objects of the same class can be equal
         if (!getClass().equals(obj.getClass())) {
             return false;

server/src/com/vaadin/data/util/filter/SimpleStringFilter.java

@@ -82,6 +82,9 @@ public final class SimpleStringFilter implements Filter {
 
     @Override
     public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
 
         // Only ones of the objects of the same class can be equal
         if (!(obj instanceof SimpleStringFilter)) {

server/tests/src/com/vaadin/data/util/sqlcontainer/filters/CompareTest.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2000-2013 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.data.util.sqlcontainer.filters;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.vaadin.data.util.filter.Compare;
+
+public class CompareTest {
+
+    @Test
+    public void testEquals() {
+        Compare c1 = new Compare.Equal("prop1", "val1");
+        Compare c2 = new Compare.Equal("prop1", "val1");
+        Assert.assertTrue(c1.equals(c2));
+    }
+
+    @Test
+    public void testDifferentTypeEquals() {
+        Compare c1 = new Compare.Equal("prop1", "val1");
+        Compare c2 = new Compare.Greater("prop1", "val1");
+        Assert.assertFalse(c1.equals(c2));
+    }
+
+    @Test
+    public void testEqualsNull() {
+        Compare c1 = new Compare.Equal("prop1", "val1");
+        Assert.assertFalse(c1.equals(null));
+    }
+}