Question

Java program question!

If I pass null to a method, how can I use the passed value to compare.

Here is example code, it might be wrong, please make it could run on eclipse.

Public class hw{

public static void main (String args[]) {

method1();

}

private static void method1() {

System.out.println(method(null));
        }

public static String method(int[] a) {
                
                return null;
        }

What I want to get in the output is just "()".

It is not just to type the string.

I want the program could check if the passed value is null.

I tried if a == null. It is not working.

Could you please tell me what is the mistake I made?

Answer 1

//do comment if any problem arises
//So you want () as output if method receives null and "" ie empty string if argument is not null
class hw {

public static void main(String args[]) {

method1();

}

private static void method1() {
System.out.println(method(null));
int[] array=new int[1];
System.out.println(method(array));
}

public static String method(int[] a) {
if (a == null)
return "()";
else
return "";
}
}

Output:

Here in first function call the argument is null and in second function call argument is integer array of size 1

So in null output is () and second output is "" ie empty string