add null check

hutool-core/src/main/java/cn/hutool/core/math/NumberUtil.java

@@ -35,7 +35,7 @@ import java.util.Set;
  * <ul>
  * <li><a href="https://github.com/venusdrogon/feilong-core/wiki/one-jdk7-bug-thinking">one-jdk7-bug-thinking</a></li>
  * </ul>
- *
+ * <p>
  * TODO 需整理精简方法，去掉无用的重载方法。
  *
  * @author Looly
@@ -1242,11 +1242,13 @@ public class NumberUtil {
 	 * @return 是否为整数
 	 */
 	public static boolean isInteger(final String s) {
+		if(StrUtil.isNotBlank(s)) {
 			try {
 				Integer.parseInt(s);
 			} catch (final NumberFormatException e) {
 				return false;
 			}
+		}
 		return true;
 	}
 
@@ -1259,11 +1261,13 @@ public class NumberUtil {
 	 * @since 4.0.0
 	 */
 	public static boolean isLong(final String s) {
+		if (StrUtil.isNotBlank(s)) {
 			try {
 				Long.parseLong(s);
 			} catch (final NumberFormatException e) {
 				return false;
 			}
+		}
 		return true;
 	}
 
@@ -1274,12 +1278,14 @@ public class NumberUtil {
 	 * @return 是否为{@link Double}类型
 	 */
 	public static boolean isDouble(final String s) {
+		if (StrUtil.isNotBlank(s)) {
 			try {
 				Double.parseDouble(s);
 				return s.contains(".");
 			} catch (final NumberFormatException ignore) {
 				// ignore
 			}
+		}
 		return false;
 	}
 

hutool-core/src/test/java/cn/hutool/core/util/NumberUtilTest.java

@@ -450,7 +450,15 @@ public class NumberUtilTest {
 
 	@Test
 	public void divIntegerTest(){
-		System.out.println(NumberUtil.div(100101300, (Number) 100));
+		final BigDecimal div = NumberUtil.div(100101300, (Number) 100);
+		Assert.assertEquals(1001013, div.intValue());
+	}
+
+	@Test
+	public void isDoubleTest(){
+		Assert.assertFalse(NumberUtil.isDouble(null));
+		Assert.assertFalse(NumberUtil.isDouble(""));
+		Assert.assertFalse(NumberUtil.isDouble("  "));
 	}
 
 }