Question

I have read up on it a bit and I understand that in java you can’t change the original value of given parameters and expect those to persist after the method is over. But I’d really like to know a good way to do this. Could someone give me some pointers on what I could do to make this method work? Thanks.

/**
* This will set values in the given array to be "" (or empty strings) if they are null values
*
* @param checkNull
*/
public static void setNullValuesBlank(String... checkNull) {
  for (int i = 0; i < checkNull.length; i++) {
    String check = checkNull[i];
    if (check == null) {
      check = "";
    }
  }
}

EDIT

So I have to set it to the array as several people mentioned, and it works great if I construct the array in the first place, but if I don’t then it doesn’t work.

Here’s the fixed method:

/**
  * This will set values in the given array to be "" (or empty strings) if they are null values
  *
  * @param checkNull
  */
public static void setNullValuesBlank(String... checkNull) {
  for (int i = 0; i < checkNull.length; i++) {
    if (checkNull[i] == null) {
      checkNull[i] = "";
    }
  }
}

Here’s a call where it works:

String s = null;
String a = null;
String[] arry = new String[]{s, a};
for (int i = 0; i < arry.length; i++) {
  System.out.println(i + ": " + arry[i]);
}
setNullValuesBlank(arry);
for (int i = 0; i < arry.length; i++) {
  System.out.println(i + ": " + arry[i]);
}

Here’s a call where it doesn’t work, but I want it to:

String q = null;
String x = null;
System.out.println("q: " + q);
System.out.println("x: " + x);
setNullValuesBlank(q, x);
System.out.println("q: " + q);
System.out.println("x: " + x);

Output of that:

q: null
x: null
q: null
x: null

Answer 1

You need to assign to the array:

if (checkNull[i] == null) {
  checkNull[i] = "";
}

Assigning to the check will not change the array.