Say we have an array named L and an input string in.
If in has a form like this [0,1,2,3], L should be an int[] containing the numbers 0, 1, 2 and 3, but if in is like this <0,1,2>, then L should be a String[] containing the Strings "0", "1" and "2".
Is this possible to do in Java? Or is there a way to define an array that accepts whatever type you put into it and then behaves like an array of that type?
I've thought about why I need this and came to the conclusion that I can kind of work around it. It requires some manual writing in the actual code, which means that it'll never be a compilable program, but unless a solution is found, I'll just use this dirty solution. Thank you for your answers!
EDIT: It seems like this problem is impossible to solve the way I want it with natural Java. I'll use the dirty solution as described above. Once again, thank you anyways. Also that strange edit was me, I didn't realize I wasn't logged in.
3 Answers
As Joe C suggested, you can store it as an Object[].
And when you need to utilize it, you can cast the whole Object[] into a int[] or String[] using code like this:
Integer[] integerArray = Arrays.copyOf(a, a.length, Integer[].class);
int[] intArray = Arrays.stream(integerArray).mapToInt(Integer::intValue).toArray();
or
String[] stringArray = Arrays.copyOf(a, a.length, String[].class);
2 Comments
Bernhard Barker
If the underlying array the
Object[] variable is a reference to is actually of type String[] or Integer[] (e.g. Object[] a = new String[5]), you can (and should) just cast it instead of using copyOf.
DavidX
After reading it again, the user's getting this in the form of a
in string. Which like you mentioned, begs the XY question. If it's coming in as a String in the first place, why would you need to make it an Object at the start.You can use an Object array because Integer and String are Object:
java.lang.Object
|
+----------+----------+
| |
v |
java.lang.Number |
| |
v v
java.lang.Integer java.lang.String
Exemple:
Object[] array = new Object[] {
0, //integer value
"hello", //String value
}
or
Object[] array = new Object[2];
array[0] = 0; //integer value
array[1] = "hello"; //String value
2 Comments
mindoverflow
Object[] L = {0,1}; System.out.println(L[1]-L[0]); This won't work, but I need it to work.If there are always two type of String, then
String s = "<1,2,4>";
Object[] oArr;
if (s.contains("["))
{
//extract the string between the bracket
s = s.substring(s.indexOf("[") + 1);
s = s.substring(0, s.indexOf("]"));
// split by comma, which return String array and convert to Integer[]
oArr = Arrays.stream(s.split(",")).mapToInt(Integer::parseInt).boxed().toArray(Integer[]::new);
}
else
{
//extract the string between the bracket
s = s.substring(s.indexOf("<") + 1);
s = s.substring(0, s.indexOf(">"));
// split by comma, which return String array
oArr = s.split(",");
}
3 Comments
mindoverflow
This produces either an array called iArr or one called sArr. I need both var names to be the the same.
Ravi
@mindoverflow JBNizet already mentioned that's not possible until we store them into
Object[]. If you are thinking about object array then, it can't be int[] instead Integer[]. Are you fine with then ?Ravi
@mindoverflow I have updated my posted as you asked.
Object[].