Guard Values against null/empty values (#1965)

* Guard Values against null/empty values

The classes modified by this commit are `DoubleValue`, `LongValue`, and
`TimeValue`. Both `null` and empty strings provided to their
constructors fail, but they provide very different error messages
(NullPointerException and StringIndexOutOfBoundsException), which is
neither sensible nor helpful in debugging.
This commit adds a guard to throw `IllegalArgumentException` for both
cases in order to improve coherency and usefulness of the error
messages.

* fix checkstyle issues

Author: pingpingy1

src/main/java/net/sf/jsqlparser/expression/DoubleValue.java

@@ -24,6 +24,9 @@ public DoubleValue() {
     }
 
     public DoubleValue(final String value) {
+        if (value == null || value.length() == 0) {
+            throw new IllegalArgumentException("value can neither be null nor empty.");
+        }
         String val = value;
         if (val.charAt(0) == '+') {
             val = val.substring(1);

src/main/java/net/sf/jsqlparser/expression/LongValue.java

@@ -26,6 +26,9 @@ public LongValue() {
     }
 
     public LongValue(final String value) {
+        if (value == null || value.length() == 0) {
+            throw new IllegalArgumentException("value can neither be null nor empty.");
+        }
         String val = value;
         if (val.charAt(0) == '+') {
             val = val.substring(1);

src/main/java/net/sf/jsqlparser/expression/TimeValue.java

@@ -25,6 +25,9 @@ public TimeValue() {
     }
 
     public TimeValue(String value) {
+        if (value == null || value.length() == 0) {
+            throw new IllegalArgumentException("value can neither be null nor empty.");
+        }
         this.value = Time.valueOf(value.substring(1, value.length() - 1));
     }
 

src/test/java/net/sf/jsqlparser/expression/DoubleValueTest.java

@@ -0,0 +1,31 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.expression;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class DoubleValueTest {
+
+    @Test
+    public void testNullValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new DoubleValue(null);
+        });
+    }
+
+    @Test
+    public void testEmptyValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new DoubleValue("");
+        });
+    }
+}

src/test/java/net/sf/jsqlparser/expression/LongValueTest.java

@@ -11,6 +11,7 @@
 
 import java.math.BigInteger;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.fail;
 import org.junit.jupiter.api.Test;
 
@@ -39,8 +40,22 @@ public void testLargeNumber() {
             value.getValue();
             fail("should not work");
         } catch (Exception e) {
-            //expected to fail
+            // expected to fail
         }
         assertEquals(new BigInteger(largeNumber), value.getBigIntegerValue());
     }
+
+    @Test
+    public void testNullStringValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new LongValue((String) null);
+        });
+    }
+
+    @Test
+    public void testEmptyStringValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new LongValue("");
+        });
+    }
 }

src/test/java/net/sf/jsqlparser/expression/TimeValueTest.java

@@ -0,0 +1,31 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.expression;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class TimeValueTest {
+
+    @Test
+    public void testNullValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new TimeValue(null);
+        });
+    }
+
+    @Test
+    public void testEmptyValue() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            new TimeValue("");
+        });
+    }
+}