如果在Java中使用AND运算子

Question

I have a block of code which uses if statement with AND operator:

final String NODE_TYPE_LIST = "List";
final String NODE_TYPE_DETAIL = "Detail";
if ((!NODE_TYPE_LIST.equalsIgnoreCase(dataNodeBean.getType())) 
                    && (!NODE_TYPE_DETAIL.equalsIgnoreCase(dataNodeBean.getType()))) {
                throw new InvalidNodeTypeException("Invalid Node type.");
            }

For exampled, if dataNodeBean.getType() returns "List". According to this link, above code should throw InvalidNodeTypeException only if both expressions in if statement returns true. But when i'm debugging the program( where dataNodeBean.getType() returns "List" ) i see both expressions being evaluated even though the first expression returns false, as a result the InvalidNodeTypeException(Custom Exception) is thrown. What i expect from this code is to throw an exception when the dataNodeBean.getType() doesn't returns either List or Detail. I don't understand what i'm doing wrong here.

Answer 1

Your code is perfectly fine. I ran the following test:

public static void main(String[] args) {
    System.out.println(test("A"));
    System.out.println(test("B"));
    System.out.println(test("C"));
}

private static boolean test(String value) {
    return (!"a".equalsIgnoreCase(value)) && (!"b".equalsIgnoreCase(value));
}

And it returned

false
false
true

Just as you'd expect. I suspect the issue is in the getType method. An easy way to confirm is to move your check to a separate method that is passed the result of getType and then write some unit test confirming that it returns true for anything other than "list" or "detail".