fix bug Calculator.conversion EmptyStackException #1984 bug

Author: GGGGeorge-gao

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

@@ -191,7 +191,7 @@ private static String transform(String expression) {
 				}
 			}
 		}
-		if (arr[0] == '~' || (arr.length > 1 && arr[1] == '(')) {
+		if (arr[0] == '~' && (arr.length > 1 && arr[1] == '(')) {
 			arr[0] = '-';
 			return "0" + new String(arr);
 		} else {

hutool-core/src/test/java/cn/hutool/core/math/CalculatorTest.java

@@ -31,10 +31,15 @@ public void conversationTest4(){
 	}
 
 	@Test
-	@Ignore
 	public void conversationTest5(){
 		// https://github.com/dromara/hutool/issues/1984
 		final double conversion = Calculator.conversion("((1/1) / (1/1) -1) * 100");
-		Assert.assertEquals((88D * 66 / 23) % 26, conversion, 2);
+		Assert.assertEquals(0, conversion, 2);
+	}
+
+	@Test
+	public void conversationTest6() {
+		final double conversion = Calculator.conversion("-((2.12-2) * 100)");
+		Assert.assertEquals(-1D * (2.12 - 2) * 100, conversion, 2);
 	}
 }